Ffplay+QT播放器

文章目录

    • 简介
    • ffplay模块划分
    • 开发环境
    • 代码
      • 下载地址
      • 编译执行
      • 代码预览

简介

有问题请加qq群进行讨论 (音视频高级开发交流群3 群号782508536)
更多FFmpeg知识:音视频FFMPEG命令从入门到提高
在Windows环境使用QT Creator 4.4.1编译ffplay(Ffmpeg3.3.3版本):

  • 去掉了参数的解析,目前只支持内部写死文件路径;
  • 支持按键事件,比如左右箭头seek,空格键暂停等;
  • 在QT编译ffplay的目的是为了方便debug,以方便观察AVPacket、AVFrame等结构体的变量。

加群讨论:音视频技术交流群3 782508536

ffplay模块划分

  • 解析输入
  • 打开码流
  • 音视频队列
  • 音视频解码
  • 播放控制
    • 开始播放
    • 停止播放
    • 暂停播放
    • 跳到(seek)指定位置播放
  • 音频输出
  • 视频输出
  • ffplay快捷键支持

开发环境

  • Windows7
  • QT 5.9.2 + Creator 4.4.1
  • 第三方库
    • FFMPEG 用来读取码流以及解码
    • SDL2 用来播放声音、显示画面

代码

下载地址

下载地址:http://download.csdn.net/download/muyuyuzhong/10272301

编译执行

将源码dll目的可执行文件和视频文件拷贝到程序运行目录,播放文件也可以自己指定位置,比如

char fileName[256] = {"G:\\迅雷下载\\绣春刀II:修罗战场.HD.720p.国语中字.mkv"};

要注意路径斜杠"\"的问题。

Ffplay+QT播放器_第1张图片

代码预览

/*
 * Copyright (c) 2003 Fabrice Bellard
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * simple media player based on the FFmpeg libraries
 */

//#include "config.h"
#include 
#include 
#include 
#include 
#include 

#ifdef __cplusplus
extern "C"
{
#endif
#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/mathematics.h"
#include "libavutil/pixdesc.h"
#include "libavutil/imgutils.h"
#include "libavutil/dict.h"
#include "libavutil/parseutils.h"
#include "libavutil/samplefmt.h"
#include "libavutil/avassert.h"
#include "libavutil/time.h"
#include "libavutil/display.h"
#include "libavformat/avformat.h"
#include "libavdevice/avdevice.h"
#include "libswscale/swscale.h"
#include "libavutil/opt.h"
#include "libavcodec/avfft.h"
#include "libswresample/swresample.h"

#define CONFIG_AVFILTER 0
#if CONFIG_AVFILTER
# include "libavfilter/avfilter.h"
# include "libavfilter/buffersink.h"
# include "libavfilter/buffersrc.h"
#endif

#include 
#include 


#ifdef __cplusplus
}
#endif

#define _WIN32
#ifdef _WIN32
#include 
#endif
#include 

AVDictionary *sws_dict;
AVDictionary *swr_opts;
AVDictionary *format_opts, *codec_opts, *resample_opts;

const char program_name[] = "ffplay";
const int program_birth_year = 2003;

#define MAX_QUEUE_SIZE (15 * 1024 * 1024)
#define MIN_FRAMES 25
#define EXTERNAL_CLOCK_MIN_FRAMES 2
#define EXTERNAL_CLOCK_MAX_FRAMES 10

/* Minimum SDL audio buffer size, in samples. */
#define SDL_AUDIO_MIN_BUFFER_SIZE 512
/* Calculate actual buffer size keeping in mind not cause too frequent audio callbacks */
#define SDL_AUDIO_MAX_CALLBACKS_PER_SEC 30

/* Step size for volume control in dB */
#define SDL_VOLUME_STEP (0.75)

/* no AV sync correction is done if below the minimum AV sync threshold */
#define AV_SYNC_THRESHOLD_MIN 0.04
/* AV sync correction is done if above the maximum AV sync threshold */
#define AV_SYNC_THRESHOLD_MAX 0.1
/* If a frame duration is longer than this, it will not be duplicated to compensate AV sync */
#define AV_SYNC_FRAMEDUP_THRESHOLD 0.1
/* no AV correction is done if too big error */
#define AV_NOSYNC_THRESHOLD 10.0

/* maximum audio speed change to get correct sync */
#define SAMPLE_CORRECTION_PERCENT_MAX 10

/* external clock speed adjustment constants for realtime sources based on buffer fullness */
#define EXTERNAL_CLOCK_SPEED_MIN  0.900
#define EXTERNAL_CLOCK_SPEED_MAX  1.010
#define EXTERNAL_CLOCK_SPEED_STEP 0.001

/* we use about AUDIO_DIFF_AVG_NB A-V differences to make the average */
#define AUDIO_DIFF_AVG_NB   20

/* polls for possible required screen refresh at least this often, should be less than 1/fps */
#define REFRESH_RATE 0.01

/* NOTE: the size must be big enough to compensate the hardware audio buffersize size */
/* TODO: We assume that a decoded and resampled frame fits into this buffer */
#define SAMPLE_ARRAY_SIZE (8 * 65536)

#define CURSOR_HIDE_DELAY 1000000

#define USE_ONEPASS_SUBTITLE_RENDER 1

static unsigned sws_flags = SWS_BICUBIC;

typedef struct MyAVPacketList {
    AVPacket pkt;
    struct MyAVPacketList *next;
    int serial;
} MyAVPacketList;

typedef struct PacketQueue {
    MyAVPacketList *first_pkt, *last_pkt;
    int nb_packets;
    int size;
    int64_t duration;
    int abort_request;
    int serial;
    SDL_mutex *mutex;
    SDL_cond *cond;
} PacketQueue;

#define VIDEO_PICTURE_QUEUE_SIZE 3
#define SUBPICTURE_QUEUE_SIZE 16
#define SAMPLE_QUEUE_SIZE 9
#define FRAME_QUEUE_SIZE FFMAX(SAMPLE_QUEUE_SIZE, FFMAX(VIDEO_PICTURE_QUEUE_SIZE, SUBPICTURE_QUEUE_SIZE))

typedef struct AudioParams {
    int freq;
    int channels;
    int64_t channel_layout;
    enum AVSampleFormat fmt;
    int frame_size;
    int bytes_per_sec;
} AudioParams;

typedef struct Clock {
    double pts;           /* clock base */
    double pts_drift;     /* clock base minus time at which we updated the clock */
    double last_updated;
    double speed;
    int serial;           /* clock is based on a packet with this serial */
    int paused;
    int *queue_serial;    /* pointer to the current packet queue serial, used for obsolete clock detection */
} Clock;

/* Common struct for handling all types of decoded data and allocated render buffers. */
typedef struct Frame {
    AVFrame *frame;
    AVSubtitle sub;
    int serial;
    double pts;           /* presentation timestamp for the frame */
    double duration;      /* estimated duration of the frame */
    int64_t pos;          /* byte position of the frame in the input file */
    int width;
    int height;
    int format;
    AVRational sar;
    int uploaded;
    int flip_v;
} Frame;

typedef struct FrameQueue {
    Frame queue[FRAME_QUEUE_SIZE];
    int rindex;
    int windex;
    int size;
    int max_size;
    int keep_last;
    int rindex_shown;
    SDL_mutex *mutex;
    SDL_cond *cond;
    PacketQueue *pktq;
} FrameQueue;

enum {
    AV_SYNC_AUDIO_MASTER, /* default choice */
    AV_SYNC_VIDEO_MASTER,
    AV_SYNC_EXTERNAL_CLOCK, /* synchronize to an external clock */
};

// 解码器
typedef struct Decoder {
    AVPacket pkt;
    AVPacket pkt_temp;
    PacketQueue *queue;
    AVCodecContext *avctx;
    int pkt_serial;
    int finished;
    int packet_pending;
    SDL_cond *empty_queue_cond;
    int64_t start_pts;
    AVRational start_pts_tb;
    int64_t next_pts;
    AVRational next_pts_tb;
    SDL_Thread *decoder_tid;
} Decoder;

enum ShowMode {
    SHOW_MODE_NONE = -1, SHOW_MODE_VIDEO = 0, SHOW_MODE_WAVES, SHOW_MODE_RDFT, SHOW_MODE_NB
} ;

typedef struct VideoState {
    SDL_Thread *read_tid;
    AVInputFormat *iformat;
    int abort_request;
    int force_refresh;
    int paused;
    int last_paused;
    int queue_attachments_req;
    int seek_req;
    int seek_flags;
    int64_t seek_pos;
    int64_t seek_rel;
    int read_pause_return;
    AVFormatContext *ic;
    int realtime;

    Clock audclk;
    Clock vidclk;
    Clock extclk;

    FrameQueue pictq;
    FrameQueue subpq;
    FrameQueue sampq;

    Decoder auddec;
    Decoder viddec;
    Decoder subdec;

    int audio_stream;

    int av_sync_type;

    double audio_clock;
    int audio_clock_serial;
    double audio_diff_cum; /* used for AV difference average computation */
    double audio_diff_avg_coef;
    double audio_diff_threshold;
    int audio_diff_avg_count;
    AVStream *audio_st;
    PacketQueue audioq;
    int audio_hw_buf_size;
    uint8_t *audio_buf;
    uint8_t *audio_buf1;
    unsigned int audio_buf_size; /* in bytes */
    unsigned int audio_buf1_size;
    int audio_buf_index; /* in bytes */
    int audio_write_buf_size;
    int audio_volume;
    int muted;
    struct AudioParams audio_src;
#if CONFIG_AVFILTER
    struct AudioParams audio_filter_src;
#endif
    struct AudioParams audio_tgt;
    struct SwrContext *swr_ctx;
    int frame_drops_early;
    int frame_drops_late;


    int16_t sample_array[SAMPLE_ARRAY_SIZE];
    int sample_array_index;
    int last_i_start;
    RDFTContext *rdft;
    int rdft_bits;
    FFTSample *rdft_data;
    int xpos;
    double last_vis_time;
    SDL_Texture *vis_texture;
    SDL_Texture *sub_texture;
    SDL_Texture *vid_texture;

    int subtitle_stream;
    AVStream *subtitle_st;
    PacketQueue subtitleq;

    double frame_timer;
    double frame_last_returned_time;
    double frame_last_filter_delay;
    int video_stream;
    AVStream *video_st;
    PacketQueue videoq;
    double max_frame_duration;      // maximum duration of a frame - above this, we consider the jump a timestamp discontinuity
    struct SwsContext *img_convert_ctx;
    struct SwsContext *sub_convert_ctx;
    int eof;

    char *filename;
    int width, height, xleft, ytop;
    int step;

#if CONFIG_AVFILTER
    int vfilter_idx;
    AVFilterContext *in_video_filter;   // the first filter in the video chain
    AVFilterContext *out_video_filter;  // the last filter in the video chain
    AVFilterContext *in_audio_filter;   // the first filter in the audio chain
    AVFilterContext *out_audio_filter;  // the last filter in the audio chain
    AVFilterGraph *agraph;              // audio filter graph
#endif

    int last_video_stream, last_audio_stream, last_subtitle_stream;

    SDL_cond *continue_read_thread;
    enum ShowMode show_mode;
} VideoState;

/* options specified by the user */
static AVInputFormat *file_iformat;
static const char *input_filename;
static const char *window_title;
static int default_width  = 640;
static int default_height = 480;
static int screen_width  = 0;
static int screen_height = 0;
static int audio_disable;
static int video_disable;
static int subtitle_disable;
static const char* wanted_stream_spec[AVMEDIA_TYPE_NB] = {0};
static int seek_by_bytes = -1;
static int display_disable;
static int borderless;
static int startup_volume = 100;
static int show_status = 1;
static int av_sync_type = AV_SYNC_AUDIO_MASTER;
static int64_t start_time = AV_NOPTS_VALUE;
static int64_t duration = AV_NOPTS_VALUE;
static int fast = 0;
static int genpts = 0;
static int lowres = 0;
static int decoder_reorder_pts = -1;
static int autoexit;
static int exit_on_keydown;
static int exit_on_mousedown;
static int loop = 1;
static int framedrop = -1;
static int infinite_buffer = -1;
static enum ShowMode show_mode = SHOW_MODE_NONE;
static const char *audio_codec_name;
static const char *subtitle_codec_name;
static const char *video_codec_name;
double rdftspeed = 0.02;
static int64_t cursor_last_shown;
static int cursor_hidden = 0;
#if CONFIG_AVFILTER
static const char **vfilters_list = NULL;
static int nb_vfilters = 0;
static char *afilters = NULL;
#endif
static int autorotate = 1;

/* current context */
static int is_full_screen;
static int64_t audio_callback_time;

static AVPacket flush_pkt;

#define FF_QUIT_EVENT    (SDL_USEREVENT + 2)

static SDL_Window *window;
static SDL_Renderer *renderer;

void exit_program(int ret)
{

    exit(ret);
}

void *grow_array(void *array, int elem_size, int *size, int new_size)
{
    if (new_size >= INT_MAX / elem_size) {
        av_log(NULL, AV_LOG_ERROR, "Array too big.\n");
        exit_program(1);
    }
    if (*size < new_size) {
        uint8_t *tmp = (uint8_t *)av_realloc_array(array, new_size, elem_size);
        if (!tmp) {
            av_log(NULL, AV_LOG_ERROR, "Could not alloc buffer.\n");
            exit_program(1);
        }
        memset(tmp + *size*elem_size, 0, (new_size-*size) * elem_size);
        *size = new_size;
        return tmp;
    }
    return array;
}

#define GROW_ARRAY(array, nb_elems)\
    array = (const char **)grow_array(array, sizeof(*array), &nb_elems, nb_elems + 1)


#if CONFIG_AVFILTER
static int opt_add_vfilter(void *optctx, const char *opt, const char *arg)
{
    GROW_ARRAY(vfilters_list, nb_vfilters);
    vfilters_list[nb_vfilters - 1] = arg;
    return 0;
}
#endif



int check_stream_specifier(AVFormatContext *s, AVStream *st, const char *spec)
{
    int ret = avformat_match_stream_specifier(s, st, spec);
    if (ret < 0)
        av_log(s, AV_LOG_ERROR, "Invalid stream specifier: %s.\n", spec);
    return ret;
}

AVDictionary *filter_codec_opts(AVDictionary *opts, enum AVCodecID codec_id,
                                AVFormatContext *s, AVStream *st, AVCodec *codec)
{
    AVDictionary    *ret = NULL;
    AVDictionaryEntry *t = NULL;
    int            flags = s->oformat ? AV_OPT_FLAG_ENCODING_PARAM
                                      : AV_OPT_FLAG_DECODING_PARAM;
    char          prefix = 0;
    const AVClass    *cc = avcodec_get_class();

    if (!codec)
        codec            = s->oformat ? avcodec_find_encoder(codec_id)
                                      : avcodec_find_decoder(codec_id);

    switch (st->codecpar->codec_type) {
    case AVMEDIA_TYPE_VIDEO:
        prefix  = 'v';
        flags  |= AV_OPT_FLAG_VIDEO_PARAM;
        break;
    case AVMEDIA_TYPE_AUDIO:
        prefix  = 'a';
        flags  |= AV_OPT_FLAG_AUDIO_PARAM;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        prefix  = 's';
        flags  |= AV_OPT_FLAG_SUBTITLE_PARAM;
        break;
    }

    while (t = av_dict_get(opts, "", t, AV_DICT_IGNORE_SUFFIX)) {
        char *p = strchr(t->key, ':');

        /* check stream specification in opt name */
        if (p)
            switch (check_stream_specifier(s, st, p + 1)) {
            case  1: *p = 0; break;
            case  0:         continue;
            default:         exit_program(1);
            }

        if (av_opt_find(&cc, t->key, NULL, flags, AV_OPT_SEARCH_FAKE_OBJ) ||
            !codec ||
            (codec->priv_class &&
             av_opt_find(&codec->priv_class, t->key, NULL, flags,
                         AV_OPT_SEARCH_FAKE_OBJ)))
            av_dict_set(&ret, t->key, t->value, 0);
        else if (t->key[0] == prefix &&
                 av_opt_find(&cc, t->key + 1, NULL, flags,
                             AV_OPT_SEARCH_FAKE_OBJ))
            av_dict_set(&ret, t->key + 1, t->value, 0);

        if (p)
            *p = ':';
    }
    return ret;
}

AVDictionary **setup_find_stream_info_opts(AVFormatContext *s,
                                           AVDictionary *codec_opts)
{
    int i;
    AVDictionary **opts;

    if (!s->nb_streams)
        return NULL;
    opts = (AVDictionary **)av_mallocz_array(s->nb_streams, sizeof(*opts));
    if (!opts) {
        av_log(NULL, AV_LOG_ERROR,
               "Could not alloc memory for stream options.\n");
        return NULL;
    }
    for (i = 0; i < s->nb_streams; i++)
        opts[i] = filter_codec_opts(codec_opts, s->streams[i]->codecpar->codec_id,
                                    s, s->streams[i], NULL);
    return opts;
}

double get_rotation(AVStream *st)
{
    uint8_t* displaymatrix = av_stream_get_side_data(st,
                                                     AV_PKT_DATA_DISPLAYMATRIX, NULL);
    double theta = 0;
    if (displaymatrix)
        theta = -av_display_rotation_get((int32_t*) displaymatrix);

    theta -= 360*floor(theta/360 + 0.9/360);

    if (fabs(theta - 90*round(theta/90)) > 2)
        av_log(NULL, AV_LOG_WARNING, "Odd rotation angle.\n"
               "If you want to help, upload a sample "
               "of this file to ftp://upload.ffmpeg.org/incoming/ "
               "and contact the ffmpeg-devel mailing list. ([email protected])");

    return theta;
}


static inline
int cmp_audio_fmts(enum AVSampleFormat fmt1, int64_t channel_count1,
                   enum AVSampleFormat fmt2, int64_t channel_count2)
{
    /* If channel count == 1, planar and non-planar formats are the same */
    if (channel_count1 == 1 && channel_count2 == 1)
        return av_get_packed_sample_fmt(fmt1) != av_get_packed_sample_fmt(fmt2);
    else
        return channel_count1 != channel_count2 || fmt1 != fmt2;
}

static inline
int64_t get_valid_channel_layout(int64_t channel_layout, int channels)
{
    if (channel_layout && av_get_channel_layout_nb_channels(channel_layout) == channels)
        return channel_layout;
    else
        return 0;
}

static int packet_queue_put_private(PacketQueue *q, AVPacket *pkt)
{
    MyAVPacketList *pkt1;

    if (q->abort_request)
       return -1;

    pkt1 = (MyAVPacketList *)av_malloc(sizeof(MyAVPacketList));
    if (!pkt1)
        return -1;
    pkt1->pkt = *pkt;
    pkt1->next = NULL;
    if (pkt == &flush_pkt)
        q->serial++;
    pkt1->serial = q->serial;

    if (!q->last_pkt)
        q->first_pkt = pkt1;
    else
        q->last_pkt->next = pkt1;
    q->last_pkt = pkt1;
    q->nb_packets++;
    q->size += pkt1->pkt.size + sizeof(*pkt1);
    q->duration += pkt1->pkt.duration;
    /* XXX: should duplicate packet data in DV case */
    SDL_CondSignal(q->cond);
    return 0;
}

static int packet_queue_put(PacketQueue *q, AVPacket *pkt)
{
    int ret;

    SDL_LockMutex(q->mutex);
    ret = packet_queue_put_private(q, pkt);
    SDL_UnlockMutex(q->mutex);

    if (pkt != &flush_pkt && ret < 0)
        av_packet_unref(pkt);

    return ret;
}

static int packet_queue_put_nullpacket(PacketQueue *q, int stream_index)
{
    AVPacket pkt1, *pkt = &pkt1;
    av_init_packet(pkt);
    pkt->data = NULL;
    pkt->size = 0;
    pkt->stream_index = stream_index;
    return packet_queue_put(q, pkt);
}

/* packet queue handling */
static int packet_queue_init(PacketQueue *q)
{
    memset(q, 0, sizeof(PacketQueue));
    q->mutex = SDL_CreateMutex();
    if (!q->mutex) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateMutex(): %s\n", SDL_GetError());
        return AVERROR(ENOMEM);
    }
    q->cond = SDL_CreateCond();
    if (!q->cond) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
        return AVERROR(ENOMEM);
    }
    q->abort_request = 1;
    return 0;
}

static void packet_queue_flush(PacketQueue *q)
{
    MyAVPacketList *pkt, *pkt1;

    SDL_LockMutex(q->mutex);
    for (pkt = q->first_pkt; pkt; pkt = pkt1) {
        pkt1 = pkt->next;
        av_packet_unref(&pkt->pkt);
        av_freep(&pkt);
    }
    q->last_pkt = NULL;
    q->first_pkt = NULL;
    q->nb_packets = 0;
    q->size = 0;
    q->duration = 0;
    SDL_UnlockMutex(q->mutex);
}

static void packet_queue_destroy(PacketQueue *q)
{
    packet_queue_flush(q);
    SDL_DestroyMutex(q->mutex);
    SDL_DestroyCond(q->cond);
}

static void packet_queue_abort(PacketQueue *q)
{
    SDL_LockMutex(q->mutex);

    q->abort_request = 1;

    SDL_CondSignal(q->cond);

    SDL_UnlockMutex(q->mutex);
}

static void packet_queue_start(PacketQueue *q)
{
    SDL_LockMutex(q->mutex);
    q->abort_request = 0;
    packet_queue_put_private(q, &flush_pkt);
    SDL_UnlockMutex(q->mutex);
}

/* return < 0 if aborted, 0 if no packet and > 0 if packet.  */
static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block, int *serial)
{
    MyAVPacketList *pkt1;
    int ret;

    SDL_LockMutex(q->mutex);

    for (;;) {
        if (q->abort_request) {
            ret = -1;
            break;
        }

        pkt1 = q->first_pkt;
        if (pkt1) {
            q->first_pkt = pkt1->next;
            if (!q->first_pkt)
                q->last_pkt = NULL;
            q->nb_packets--;
            q->size -= pkt1->pkt.size + sizeof(*pkt1);
            q->duration -= pkt1->pkt.duration;
            *pkt = pkt1->pkt;
            if (serial)
                *serial = pkt1->serial;
            av_free(pkt1);
            ret = 1;
            break;
        } else if (!block) {
            ret = 0;
            break;
        } else {
            SDL_CondWait(q->cond, q->mutex);
        }
    }
    SDL_UnlockMutex(q->mutex);
    return ret;
}

static void decoder_init(Decoder *d, AVCodecContext *avctx, PacketQueue *queue, SDL_cond *empty_queue_cond) {
    memset(d, 0, sizeof(Decoder));
    d->avctx = avctx;
    d->queue = queue;
    d->empty_queue_cond = empty_queue_cond;
    d->start_pts = AV_NOPTS_VALUE;
}

// 解码
static int decoder_decode_frame(Decoder *d, AVFrame *frame, AVSubtitle *sub) {
    int got_frame = 0;

    do {
        int ret = -1;

        if (d->queue->abort_request)
            return -1;

        if (!d->packet_pending || d->queue->serial != d->pkt_serial) {
            AVPacket pkt;
            do {
                if (d->queue->nb_packets == 0)
                    SDL_CondSignal(d->empty_queue_cond);
                if (packet_queue_get(d->queue, &pkt, 1, &d->pkt_serial) < 0)
                    return -1;
                if (pkt.data == flush_pkt.data) {
                    avcodec_flush_buffers(d->avctx);
                    d->finished = 0;
                    d->next_pts = d->start_pts;
                    d->next_pts_tb = d->start_pts_tb;
                }
            } while (pkt.data == flush_pkt.data || d->queue->serial != d->pkt_serial);
            av_packet_unref(&d->pkt);
            d->pkt_temp = d->pkt = pkt;
            d->packet_pending = 1;
        }

        switch (d->avctx->codec_type) {
            case AVMEDIA_TYPE_VIDEO:
                ret = avcodec_decode_video2(d->avctx, frame, &got_frame, &d->pkt_temp);
                if (got_frame) {
                    if (decoder_reorder_pts == -1) {
                        frame->pts = av_frame_get_best_effort_timestamp(frame);
                    } else if (!decoder_reorder_pts) {
                        frame->pts = frame->pkt_dts;
                    }
                }
                break;
            case AVMEDIA_TYPE_AUDIO:
                ret = avcodec_decode_audio4(d->avctx, frame, &got_frame, &d->pkt_temp);
                if (got_frame) {
                    AVRational tb = (AVRational){1, frame->sample_rate};
                    if (frame->pts != AV_NOPTS_VALUE)
                        frame->pts = av_rescale_q(frame->pts, av_codec_get_pkt_timebase(d->avctx), tb);
                    else if (d->next_pts != AV_NOPTS_VALUE)
                        frame->pts = av_rescale_q(d->next_pts, d->next_pts_tb, tb);
                    if (frame->pts != AV_NOPTS_VALUE) {
                        d->next_pts = frame->pts + frame->nb_samples;
                        d->next_pts_tb = tb;
                    }
                }
                break;
            case AVMEDIA_TYPE_SUBTITLE:
                ret = avcodec_decode_subtitle2(d->avctx, sub, &got_frame, &d->pkt_temp);
                break;
        }

        if (ret < 0) {
            d->packet_pending = 0;
        } else {
            d->pkt_temp.dts =
            d->pkt_temp.pts = AV_NOPTS_VALUE;
            if (d->pkt_temp.data) {
                if (d->avctx->codec_type != AVMEDIA_TYPE_AUDIO)
                    ret = d->pkt_temp.size;
                d->pkt_temp.data += ret;
                d->pkt_temp.size -= ret;
                if (d->pkt_temp.size <= 0)
                    d->packet_pending = 0;
            } else {
                if (!got_frame) {
                    d->packet_pending = 0;
                    d->finished = d->pkt_serial;
                }
            }
        }
    } while (!got_frame && !d->finished);

    return got_frame;
}

static void decoder_destroy(Decoder *d) {
    av_packet_unref(&d->pkt);
    avcodec_free_context(&d->avctx);
}

static void frame_queue_unref_item(Frame *vp)
{
    av_frame_unref(vp->frame);
    avsubtitle_free(&vp->sub);
}

static int frame_queue_init(FrameQueue *f, PacketQueue *pktq, int max_size, int keep_last)
{
    int i;
    memset(f, 0, sizeof(FrameQueue));
    if (!(f->mutex = SDL_CreateMutex())) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateMutex(): %s\n", SDL_GetError());
        return AVERROR(ENOMEM);
    }
    if (!(f->cond = SDL_CreateCond())) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
        return AVERROR(ENOMEM);
    }
    f->pktq = pktq;
    f->max_size = FFMIN(max_size, FRAME_QUEUE_SIZE);
    f->keep_last = !!keep_last;
    for (i = 0; i < f->max_size; i++)
        if (!(f->queue[i].frame = av_frame_alloc()))
            return AVERROR(ENOMEM);
    return 0;
}

static void frame_queue_destory(FrameQueue *f)
{
    int i;
    for (i = 0; i < f->max_size; i++) {
        Frame *vp = &f->queue[i];
        frame_queue_unref_item(vp);
        av_frame_free(&vp->frame);
    }
    SDL_DestroyMutex(f->mutex);
    SDL_DestroyCond(f->cond);
}

static void frame_queue_signal(FrameQueue *f)
{
    SDL_LockMutex(f->mutex);
    SDL_CondSignal(f->cond);
    SDL_UnlockMutex(f->mutex);
}

static Frame *frame_queue_peek(FrameQueue *f)
{
    return &f->queue[(f->rindex + f->rindex_shown) % f->max_size];
}

static Frame *frame_queue_peek_next(FrameQueue *f)
{
    return &f->queue[(f->rindex + f->rindex_shown + 1) % f->max_size];
}

static Frame *frame_queue_peek_last(FrameQueue *f)
{
    return &f->queue[f->rindex];
}

static Frame *frame_queue_peek_writable(FrameQueue *f)
{
    /* wait until we have space to put a new frame */
    SDL_LockMutex(f->mutex);
    while (f->size >= f->max_size &&
           !f->pktq->abort_request) {
        SDL_CondWait(f->cond, f->mutex);
    }
    SDL_UnlockMutex(f->mutex);

    if (f->pktq->abort_request)
        return NULL;

    return &f->queue[f->windex];
}

static Frame *frame_queue_peek_readable(FrameQueue *f)
{
    /* wait until we have a readable a new frame */
    SDL_LockMutex(f->mutex);
    while (f->size - f->rindex_shown <= 0 &&
           !f->pktq->abort_request) {
        SDL_CondWait(f->cond, f->mutex);
    }
    SDL_UnlockMutex(f->mutex);

    if (f->pktq->abort_request)
        return NULL;

    return &f->queue[(f->rindex + f->rindex_shown) % f->max_size];
}

static void frame_queue_push(FrameQueue *f)
{
    if (++f->windex == f->max_size)
        f->windex = 0;
    SDL_LockMutex(f->mutex);
    f->size++;
    SDL_CondSignal(f->cond);
    SDL_UnlockMutex(f->mutex);
}

static void frame_queue_next(FrameQueue *f)
{
    if (f->keep_last && !f->rindex_shown) {
        f->rindex_shown = 1;
        return;
    }
    frame_queue_unref_item(&f->queue[f->rindex]);
    if (++f->rindex == f->max_size)
        f->rindex = 0;
    SDL_LockMutex(f->mutex);
    f->size--;
    SDL_CondSignal(f->cond);
    SDL_UnlockMutex(f->mutex);
}

/* return the number of undisplayed frames in the queue */
static int frame_queue_nb_remaining(FrameQueue *f)
{
    return f->size - f->rindex_shown;
}

/* return last shown position */
static int64_t frame_queue_last_pos(FrameQueue *f)
{
    Frame *fp = &f->queue[f->rindex];
    if (f->rindex_shown && fp->serial == f->pktq->serial)
        return fp->pos;
    else
        return -1;
}

static void decoder_abort(Decoder *d, FrameQueue *fq)
{
    packet_queue_abort(d->queue);
    frame_queue_signal(fq);
    SDL_WaitThread(d->decoder_tid, NULL);
    d->decoder_tid = NULL;
    packet_queue_flush(d->queue);
}

static inline void fill_rectangle(int x, int y, int w, int h)
{
    SDL_Rect rect;
    rect.x = x;
    rect.y = y;
    rect.w = w;
    rect.h = h;
    if (w && h)
        SDL_RenderFillRect(renderer, &rect);
}

static int realloc_texture(SDL_Texture **texture, Uint32 new_format, int new_width, int new_height, SDL_BlendMode blendmode, int init_texture)
{
    Uint32 format;
    int access, w, h;
    if (SDL_QueryTexture(*texture, &format, &access, &w, &h) < 0 || new_width != w || new_height != h || new_format != format) {
        void *pixels;
        int pitch;
        SDL_DestroyTexture(*texture);
        if (!(*texture = SDL_CreateTexture(renderer, new_format, SDL_TEXTUREACCESS_STREAMING, new_width, new_height)))
            return -1;
        if (SDL_SetTextureBlendMode(*texture, blendmode) < 0)
            return -1;
        if (init_texture) {
            if (SDL_LockTexture(*texture, NULL, &pixels, &pitch) < 0)
                return -1;
            memset(pixels, 0, pitch * new_height);
            SDL_UnlockTexture(*texture);
        }
    }
    return 0;
}

static void calculate_display_rect(SDL_Rect *rect,
                                   int scr_xleft, int scr_ytop, int scr_width, int scr_height,
                                   int pic_width, int pic_height, AVRational pic_sar)
{
    float aspect_ratio;
    int width, height, x, y;

    if (pic_sar.num == 0)
        aspect_ratio = 0;
    else
        aspect_ratio = av_q2d(pic_sar);

    if (aspect_ratio <= 0.0)
        aspect_ratio = 1.0;
    aspect_ratio *= (float)pic_width / (float)pic_height;

    /* XXX: we suppose the screen has a 1.0 pixel ratio */
    height = scr_height;
    width = lrint(height * aspect_ratio) & ~1;
    if (width > scr_width) {
        width = scr_width;
        height = lrint(width / aspect_ratio) & ~1;
    }
    x = (scr_width - width) / 2;
    y = (scr_height - height) / 2;
    rect->x = scr_xleft + x;
    rect->y = scr_ytop  + y;
    rect->w = FFMAX(width,  1);
    rect->h = FFMAX(height, 1);
}

static int upload_texture(SDL_Texture *tex, AVFrame *frame, struct SwsContext **img_convert_ctx) {
    int ret = 0;
    switch (frame->format) {
        case AV_PIX_FMT_YUV420P:
            if (frame->linesize[0] < 0 || frame->linesize[1] < 0 || frame->linesize[2] < 0) {
                av_log(NULL, AV_LOG_ERROR, "Negative linesize is not supported for YUV.\n");
                return -1;
            }
            ret = SDL_UpdateYUVTexture(tex, NULL, frame->data[0], frame->linesize[0],
                                                  frame->data[1], frame->linesize[1],
                                                  frame->data[2], frame->linesize[2]);
            break;
        case AV_PIX_FMT_BGRA:
            if (frame->linesize[0] < 0) {
                ret = SDL_UpdateTexture(tex, NULL, frame->data[0] + frame->linesize[0] * (frame->height - 1), -frame->linesize[0]);
            } else {
                ret = SDL_UpdateTexture(tex, NULL, frame->data[0], frame->linesize[0]);
            }
            break;
        default:
            /* This should only happen if we are not using avfilter... */
            *img_convert_ctx = sws_getCachedContext(*img_convert_ctx,
                frame->width, frame->height, (enum AVPixelFormat)frame->format, frame->width, frame->height,
                AV_PIX_FMT_BGRA, sws_flags, NULL, NULL, NULL);
            if (*img_convert_ctx != NULL) {
                uint8_t *pixels[4];
                int pitch[4];
                if (!SDL_LockTexture(tex, NULL, (void **)pixels, pitch)) {
                    sws_scale(*img_convert_ctx, (const uint8_t * const *)frame->data, frame->linesize,
                              0, frame->height, pixels, pitch);
                    SDL_UnlockTexture(tex);
                }
            } else {
                av_log(NULL, AV_LOG_FATAL, "Cannot initialize the conversion context\n");
                ret = -1;
            }
            break;
    }
    return ret;
}

static void video_image_display(VideoState *is)
{
    Frame *vp;
    Frame *sp = NULL;
    SDL_Rect rect;

    vp = frame_queue_peek_last(&is->pictq);
    if (is->subtitle_st) {
        if (frame_queue_nb_remaining(&is->subpq) > 0) {
            sp = frame_queue_peek(&is->subpq);

            if (vp->pts >= sp->pts + ((float) sp->sub.start_display_time / 1000)) {
                if (!sp->uploaded) {
                    uint8_t* pixels[4];
                    int pitch[4];
                    int i;
                    if (!sp->width || !sp->height) {
                        sp->width = vp->width;
                        sp->height = vp->height;
                    }
                    if (realloc_texture(&is->sub_texture, SDL_PIXELFORMAT_ARGB8888, sp->width, sp->height, SDL_BLENDMODE_BLEND, 1) < 0)
                        return;

                    for (i = 0; i < sp->sub.num_rects; i++) {
                        AVSubtitleRect *sub_rect = sp->sub.rects[i];

                        sub_rect->x = av_clip(sub_rect->x, 0, sp->width );
                        sub_rect->y = av_clip(sub_rect->y, 0, sp->height);
                        sub_rect->w = av_clip(sub_rect->w, 0, sp->width  - sub_rect->x);
                        sub_rect->h = av_clip(sub_rect->h, 0, sp->height - sub_rect->y);

                        is->sub_convert_ctx = sws_getCachedContext(is->sub_convert_ctx,
                            sub_rect->w, sub_rect->h, AV_PIX_FMT_PAL8,
                            sub_rect->w, sub_rect->h, AV_PIX_FMT_BGRA,
                            0, NULL, NULL, NULL);
                        if (!is->sub_convert_ctx) {
                            av_log(NULL, AV_LOG_FATAL, "Cannot initialize the conversion context\n");
                            return;
                        }
                        if (!SDL_LockTexture(is->sub_texture, (SDL_Rect *)sub_rect, (void **)pixels, pitch)) {
                            sws_scale(is->sub_convert_ctx, (const uint8_t * const *)sub_rect->data, sub_rect->linesize,
                                      0, sub_rect->h, pixels, pitch);
                            SDL_UnlockTexture(is->sub_texture);
                        }
                    }
                    sp->uploaded = 1;
                }
            } else
                sp = NULL;
        }
    }

    calculate_display_rect(&rect, is->xleft, is->ytop, is->width, is->height, vp->width, vp->height, vp->sar);

    if (!vp->uploaded) {
        int sdl_pix_fmt = vp->frame->format == AV_PIX_FMT_YUV420P ? SDL_PIXELFORMAT_YV12 : SDL_PIXELFORMAT_ARGB8888;
        if (realloc_texture(&is->vid_texture, sdl_pix_fmt, vp->frame->width, vp->frame->height, SDL_BLENDMODE_NONE, 0) < 0)
            return;
        if (upload_texture(is->vid_texture, vp->frame, &is->img_convert_ctx) < 0)
            return;
        vp->uploaded = 1;
        vp->flip_v = vp->frame->linesize[0] < 0;
    }

    SDL_RenderCopyEx(renderer, is->vid_texture, NULL, &rect, 0, NULL, (SDL_RendererFlip)(vp->flip_v ? SDL_FLIP_VERTICAL : 0));
    if (sp) {
#if USE_ONEPASS_SUBTITLE_RENDER
        SDL_RenderCopy(renderer, is->sub_texture, NULL, &rect);
#else
        int i;
        double xratio = (double)rect.w / (double)sp->width;
        double yratio = (double)rect.h / (double)sp->height;
        for (i = 0; i < sp->sub.num_rects; i++) {
            SDL_Rect *sub_rect = (SDL_Rect*)sp->sub.rects[i];
            SDL_Rect target = {.x = rect.x + sub_rect->x * xratio,
                               .y = rect.y + sub_rect->y * yratio,
                               .w = sub_rect->w * xratio,
                               .h = sub_rect->h * yratio};
            SDL_RenderCopy(renderer, is->sub_texture, sub_rect, &target);
        }
#endif
    }
}

static inline int compute_mod(int a, int b)
{
    return a < 0 ? a%b + b : a%b;
}

static void video_audio_display(VideoState *s)
{
    int i, i_start, x, y1, y, ys, delay, n, nb_display_channels;
    int ch, channels, h, h2;
    int64_t time_diff;
    int rdft_bits, nb_freq;

    for (rdft_bits = 1; (1 << rdft_bits) < 2 * s->height; rdft_bits++)
        ;
    nb_freq = 1 << (rdft_bits - 1);

    /* compute display index : center on currently output samples */
    channels = s->audio_tgt.channels;
    nb_display_channels = channels;
    if (!s->paused) {
        int data_used= s->show_mode == SHOW_MODE_WAVES ? s->width : (2*nb_freq);
        n = 2 * channels;
        delay = s->audio_write_buf_size;
        delay /= n;

        /* to be more precise, we take into account the time spent since
           the last buffer computation */
        if (audio_callback_time) {
            time_diff = av_gettime_relative() - audio_callback_time;
            delay -= (time_diff * s->audio_tgt.freq) / 1000000;
        }

        delay += 2 * data_used;
        if (delay < data_used)
            delay = data_used;

        i_start= x = compute_mod(s->sample_array_index - delay * channels, SAMPLE_ARRAY_SIZE);
        if (s->show_mode == SHOW_MODE_WAVES) {
            h = INT_MIN;
            for (i = 0; i < 1000; i += channels) {
                int idx = (SAMPLE_ARRAY_SIZE + x - i) % SAMPLE_ARRAY_SIZE;
                int a = s->sample_array[idx];
                int b = s->sample_array[(idx + 4 * channels) % SAMPLE_ARRAY_SIZE];
                int c = s->sample_array[(idx + 5 * channels) % SAMPLE_ARRAY_SIZE];
                int d = s->sample_array[(idx + 9 * channels) % SAMPLE_ARRAY_SIZE];
                int score = a - d;
                if (h < score && (b ^ c) < 0) {
                    h = score;
                    i_start = idx;
                }
            }
        }

        s->last_i_start = i_start;
    } else {
        i_start = s->last_i_start;
    }

    if (s->show_mode == SHOW_MODE_WAVES) {
        SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);

        /* total height for one channel */
        h = s->height / nb_display_channels;
        /* graph height / 2 */
        h2 = (h * 9) / 20;
        for (ch = 0; ch < nb_display_channels; ch++) {
            i = i_start + ch;
            y1 = s->ytop + ch * h + (h / 2); /* position of center line */
            for (x = 0; x < s->width; x++) {
                y = (s->sample_array[i] * h2) >> 15;
                if (y < 0) {
                    y = -y;
                    ys = y1 - y;
                } else {
                    ys = y1;
                }
                fill_rectangle(s->xleft + x, ys, 1, y);
                i += channels;
                if (i >= SAMPLE_ARRAY_SIZE)
                    i -= SAMPLE_ARRAY_SIZE;
            }
        }

        SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);

        for (ch = 1; ch < nb_display_channels; ch++) {
            y = s->ytop + ch * h;
            fill_rectangle(s->xleft, y, s->width, 1);
        }
    } else {
        if (realloc_texture(&s->vis_texture, SDL_PIXELFORMAT_ARGB8888, s->width, s->height, SDL_BLENDMODE_NONE, 1) < 0)
            return;

        nb_display_channels= FFMIN(nb_display_channels, 2);
        if (rdft_bits != s->rdft_bits) {
            av_rdft_end(s->rdft);
            av_free(s->rdft_data);
            s->rdft = av_rdft_init(rdft_bits, DFT_R2C);
            s->rdft_bits = rdft_bits;
            s->rdft_data = (FFTSample *)av_malloc_array(nb_freq, 4 *sizeof(*s->rdft_data));
        }
        if (!s->rdft || !s->rdft_data){
            av_log(NULL, AV_LOG_ERROR, "Failed to allocate buffers for RDFT, switching to waves display\n");
            s->show_mode = SHOW_MODE_WAVES;
        } else {
            FFTSample *data[2];
            SDL_Rect rect = {.x = s->xpos, .y = 0, .w = 1, .h = s->height};
            uint32_t *pixels;
            int pitch;
            for (ch = 0; ch < nb_display_channels; ch++) {
                data[ch] = s->rdft_data + 2 * nb_freq * ch;
                i = i_start + ch;
                for (x = 0; x < 2 * nb_freq; x++) {
                    double w = (x-nb_freq) * (1.0 / nb_freq);
                    data[ch][x] = s->sample_array[i] * (1.0 - w * w);
                    i += channels;
                    if (i >= SAMPLE_ARRAY_SIZE)
                        i -= SAMPLE_ARRAY_SIZE;
                }
                av_rdft_calc(s->rdft, data[ch]);
            }
            /* Least efficient way to do this, we should of course
             * directly access it but it is more than fast enough. */
            if (!SDL_LockTexture(s->vis_texture, &rect, (void **)&pixels, &pitch)) {
                pitch >>= 2;
                pixels += pitch * s->height;
                for (y = 0; y < s->height; y++) {
                    double w = 1 / sqrt(nb_freq);
                    int a = sqrt(w * sqrt(data[0][2 * y + 0] * data[0][2 * y + 0] + data[0][2 * y + 1] * data[0][2 * y + 1]));
                    int b = (nb_display_channels == 2 ) ? sqrt(w * hypot(data[1][2 * y + 0], data[1][2 * y + 1]))
                                                        : a;
                    a = FFMIN(a, 255);
                    b = FFMIN(b, 255);
                    pixels -= pitch;
                    *pixels = (a << 16) + (b << 8) + ((a+b) >> 1);
                }
                SDL_UnlockTexture(s->vis_texture);
            }
            SDL_RenderCopy(renderer, s->vis_texture, NULL, NULL);
        }
        if (!s->paused)
            s->xpos++;
        if (s->xpos >= s->width)
            s->xpos= s->xleft;
    }
}

static void stream_component_close(VideoState *is, int stream_index)
{
    AVFormatContext *ic = is->ic;
    AVCodecParameters *codecpar;

    if (stream_index < 0 || stream_index >= ic->nb_streams)
        return;
    codecpar = ic->streams[stream_index]->codecpar;

    switch (codecpar->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
        decoder_abort(&is->auddec, &is->sampq);
        SDL_CloseAudio();
        decoder_destroy(&is->auddec);
        swr_free(&is->swr_ctx);
        av_freep(&is->audio_buf1);
        is->audio_buf1_size = 0;
        is->audio_buf = NULL;

        if (is->rdft) {
            av_rdft_end(is->rdft);
            av_freep(&is->rdft_data);
            is->rdft = NULL;
            is->rdft_bits = 0;
        }
        break;
    case AVMEDIA_TYPE_VIDEO:
        decoder_abort(&is->viddec, &is->pictq);
        decoder_destroy(&is->viddec);
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        decoder_abort(&is->subdec, &is->subpq);
        decoder_destroy(&is->subdec);
        break;
    default:
        break;
    }

    ic->streams[stream_index]->discard = AVDISCARD_ALL;
    switch (codecpar->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
        is->audio_st = NULL;
        is->audio_stream = -1;
        break;
    case AVMEDIA_TYPE_VIDEO:
        is->video_st = NULL;
        is->video_stream = -1;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        is->subtitle_st = NULL;
        is->subtitle_stream = -1;
        break;
    default:
        break;
    }
}

static void stream_close(VideoState *is)
{
    /* XXX: use a special url_shutdown call to abort parse cleanly */
    is->abort_request = 1;
    SDL_WaitThread(is->read_tid, NULL);

    /* close each stream */
    if (is->audio_stream >= 0)
        stream_component_close(is, is->audio_stream);
    if (is->video_stream >= 0)
        stream_component_close(is, is->video_stream);
    if (is->subtitle_stream >= 0)
        stream_component_close(is, is->subtitle_stream);

    avformat_close_input(&is->ic);

    packet_queue_destroy(&is->videoq);
    packet_queue_destroy(&is->audioq);
    packet_queue_destroy(&is->subtitleq);

    /* free all pictures */
    frame_queue_destory(&is->pictq);
    frame_queue_destory(&is->sampq);
    frame_queue_destory(&is->subpq);
    SDL_DestroyCond(is->continue_read_thread);
    sws_freeContext(is->img_convert_ctx);
    sws_freeContext(is->sub_convert_ctx);
    av_free(is->filename);
    if (is->vis_texture)
        SDL_DestroyTexture(is->vis_texture);
    if (is->vid_texture)
        SDL_DestroyTexture(is->vid_texture);
    if (is->sub_texture)
        SDL_DestroyTexture(is->sub_texture);
    av_free(is);
}

static void do_exit(VideoState *is)
{
    if (is) {
        stream_close(is);
    }
    if (renderer)
        SDL_DestroyRenderer(renderer);
    if (window)
        SDL_DestroyWindow(window);
    av_lockmgr_register(NULL);
#if CONFIG_AVFILTER
    av_freep(&vfilters_list);
#endif
    avformat_network_deinit();
    if (show_status)
        printf("\n");
    SDL_Quit();
    av_log(NULL, AV_LOG_QUIET, "%s", "");
    exit(0);
}

static void sigterm_handler(int sig)
{
    exit(123);
}

static void set_default_window_size(int width, int height, AVRational sar)
{
    SDL_Rect rect;
    calculate_display_rect(&rect, 0, 0, INT_MAX, height, width, height, sar);
    default_width  = rect.w;
    default_height = rect.h;
}

static int video_open(VideoState *is)
{
    int w,h;

    if (screen_width) {
        w = screen_width;
        h = screen_height;
    } else {
        w = default_width;
        h = default_height;
    }

    if (!window) {
        int flags = SDL_WINDOW_SHOWN;
        if (!window_title)
            window_title = input_filename;
        if (is_full_screen)
            flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
        if (borderless)
            flags |= SDL_WINDOW_BORDERLESS;
        else
            flags |= SDL_WINDOW_RESIZABLE;
        window = SDL_CreateWindow(window_title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, w, h, flags);
        SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");
        if (window) {
            SDL_RendererInfo info;
            renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
            if (!renderer) {
                av_log(NULL, AV_LOG_WARNING, "Failed to initialize a hardware accelerated renderer: %s\n", SDL_GetError());
                renderer = SDL_CreateRenderer(window, -1, 0);
            }
            if (renderer) {
                if (!SDL_GetRendererInfo(renderer, &info))
                    av_log(NULL, AV_LOG_VERBOSE, "Initialized %s renderer.\n", info.name);
            }
        }
    } else {
        SDL_SetWindowSize(window, w, h);
    }

    if (!window || !renderer) {
        av_log(NULL, AV_LOG_FATAL, "SDL: could not set video mode - exiting\n");
        do_exit(is);
    }

    is->width  = w;
    is->height = h;

    return 0;
}

/* display the current picture, if any */
static void video_display(VideoState *is)
{
    if (!window)
        video_open(is);

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);
    if (is->audio_st && is->show_mode != SHOW_MODE_VIDEO)
        video_audio_display(is);
    else if (is->video_st)
        video_image_display(is);
    SDL_RenderPresent(renderer);
}

static double get_clock(Clock *c)
{
    if (*c->queue_serial != c->serial)
        return NAN;
    if (c->paused) {
        return c->pts;
    } else {
        double time = av_gettime_relative() / 1000000.0;
        return c->pts_drift + time - (time - c->last_updated) * (1.0 - c->speed);
    }
}

static void set_clock_at(Clock *c, double pts, int serial, double time)
{
    c->pts = pts;
    c->last_updated = time;
    c->pts_drift = c->pts - time;
    c->serial = serial;
}

static void set_clock(Clock *c, double pts, int serial)
{
    double time = av_gettime_relative() / 1000000.0;
    set_clock_at(c, pts, serial, time);
}

static void set_clock_speed(Clock *c, double speed)
{
    set_clock(c, get_clock(c), c->serial);
    c->speed = speed;
}

static void init_clock(Clock *c, int *queue_serial)
{
    c->speed = 1.0;
    c->paused = 0;
    c->queue_serial = queue_serial;
    set_clock(c, NAN, -1);
}

static void sync_clock_to_slave(Clock *c, Clock *slave)
{
    double clock = get_clock(c);
    double slave_clock = get_clock(slave);
    if (!isnan(slave_clock) && (isnan(clock) || fabs(clock - slave_clock) > AV_NOSYNC_THRESHOLD))
        set_clock(c, slave_clock, slave->serial);
}

static int get_master_sync_type(VideoState *is) {
    if (is->av_sync_type == AV_SYNC_VIDEO_MASTER) {
        if (is->video_st)
            return AV_SYNC_VIDEO_MASTER;
        else
            return AV_SYNC_AUDIO_MASTER;
    } else if (is->av_sync_type == AV_SYNC_AUDIO_MASTER) {
        if (is->audio_st)
            return AV_SYNC_AUDIO_MASTER;
        else
            return AV_SYNC_EXTERNAL_CLOCK;
    } else {
        return AV_SYNC_EXTERNAL_CLOCK;
    }
}

/* get the current master clock value */
static double get_master_clock(VideoState *is)
{
    double val;

    switch (get_master_sync_type(is)) {
        case AV_SYNC_VIDEO_MASTER:
            val = get_clock(&is->vidclk);
            break;
        case AV_SYNC_AUDIO_MASTER:
            val = get_clock(&is->audclk);
            break;
        default:
            val = get_clock(&is->extclk);
            break;
    }
    return val;
}

static void check_external_clock_speed(VideoState *is) {
   if (is->video_stream >= 0 && is->videoq.nb_packets <= EXTERNAL_CLOCK_MIN_FRAMES ||
       is->audio_stream >= 0 && is->audioq.nb_packets <= EXTERNAL_CLOCK_MIN_FRAMES) {
       set_clock_speed(&is->extclk, FFMAX(EXTERNAL_CLOCK_SPEED_MIN, is->extclk.speed - EXTERNAL_CLOCK_SPEED_STEP));
   } else if ((is->video_stream < 0 || is->videoq.nb_packets > EXTERNAL_CLOCK_MAX_FRAMES) &&
              (is->audio_stream < 0 || is->audioq.nb_packets > EXTERNAL_CLOCK_MAX_FRAMES)) {
       set_clock_speed(&is->extclk, FFMIN(EXTERNAL_CLOCK_SPEED_MAX, is->extclk.speed + EXTERNAL_CLOCK_SPEED_STEP));
   } else {
       double speed = is->extclk.speed;
       if (speed != 1.0)
           set_clock_speed(&is->extclk, speed + EXTERNAL_CLOCK_SPEED_STEP * (1.0 - speed) / fabs(1.0 - speed));
   }
}

/* seek in the stream */
static void stream_seek(VideoState *is, int64_t pos, int64_t rel, int seek_by_bytes)
{
    if (!is->seek_req) {
        is->seek_pos = pos;
        is->seek_rel = rel;
        is->seek_flags &= ~AVSEEK_FLAG_BYTE;
        if (seek_by_bytes)
            is->seek_flags |= AVSEEK_FLAG_BYTE;
        is->seek_req = 1;
        SDL_CondSignal(is->continue_read_thread);
    }
}

/* pause or resume the video */
static void stream_toggle_pause(VideoState *is)
{
    if (is->paused) {
        is->frame_timer += av_gettime_relative() / 1000000.0 - is->vidclk.last_updated;
        if (is->read_pause_return != AVERROR(ENOSYS)) {
            is->vidclk.paused = 0;
        }
        set_clock(&is->vidclk, get_clock(&is->vidclk), is->vidclk.serial);
    }
    set_clock(&is->extclk, get_clock(&is->extclk), is->extclk.serial);
    is->paused = is->audclk.paused = is->vidclk.paused = is->extclk.paused = !is->paused;
}

static void toggle_pause(VideoState *is)
{
    stream_toggle_pause(is);
    is->step = 0;
}

static void toggle_mute(VideoState *is)
{
    is->muted = !is->muted;
}

static void update_volume(VideoState *is, int sign, double step)
{
    double volume_level = is->audio_volume ? (20 * log(is->audio_volume / (double)SDL_MIX_MAXVOLUME) / log(10)) : -1000.0;
    int new_volume = lrint(SDL_MIX_MAXVOLUME * pow(10.0, (volume_level + sign * step) / 20.0));
    is->audio_volume = av_clip(is->audio_volume == new_volume ? (is->audio_volume + sign) : new_volume, 0, SDL_MIX_MAXVOLUME);
}

static void step_to_next_frame(VideoState *is)
{
    /* if the stream is paused unpause it, then step */
    if (is->paused)
        stream_toggle_pause(is);
    is->step = 1;
}

static double compute_target_delay(double delay, VideoState *is)
{
    double sync_threshold, diff = 0;

    /* update delay to follow master synchronisation source */
    if (get_master_sync_type(is) != AV_SYNC_VIDEO_MASTER) {
        /* if video is slave, we try to correct big delays by
           duplicating or deleting a frame */
        diff = get_clock(&is->vidclk) - get_master_clock(is);

        /* skip or repeat frame. We take into account the
           delay to compute the threshold. I still don't know
           if it is the best guess */
        sync_threshold = FFMAX(AV_SYNC_THRESHOLD_MIN, FFMIN(AV_SYNC_THRESHOLD_MAX, delay));
        if (!isnan(diff) && fabs(diff) < is->max_frame_duration) {
            if (diff <= -sync_threshold)
                delay = FFMAX(0, delay + diff);
            else if (diff >= sync_threshold && delay > AV_SYNC_FRAMEDUP_THRESHOLD)
                delay = delay + diff;
            else if (diff >= sync_threshold)
                delay = 2 * delay;
        }
    }

    av_log(NULL, AV_LOG_TRACE, "video: delay=%0.3f A-V=%f\n",
            delay, -diff);

    return delay;
}

static double vp_duration(VideoState *is, Frame *vp, Frame *nextvp) {
    if (vp->serial == nextvp->serial) {
        double duration = nextvp->pts - vp->pts;
        if (isnan(duration) || duration <= 0 || duration > is->max_frame_duration)
            return vp->duration;
        else
            return duration;
    } else {
        return 0.0;
    }
}

static void update_video_pts(VideoState *is, double pts, int64_t pos, int serial) {
    /* update current video pts */
    set_clock(&is->vidclk, pts, serial);
    sync_clock_to_slave(&is->extclk, &is->vidclk);
}

/* called to display each frame */
static void video_refresh(void *opaque, double *remaining_time)
{
    VideoState *is = (VideoState *)opaque;
    double time;

    Frame *sp, *sp2;

    if (!is->paused && get_master_sync_type(is) == AV_SYNC_EXTERNAL_CLOCK && is->realtime)
        check_external_clock_speed(is);

    if (!display_disable && is->show_mode != SHOW_MODE_VIDEO && is->audio_st) {
        time = av_gettime_relative() / 1000000.0;
        if (is->force_refresh || is->last_vis_time + rdftspeed < time) {
            video_display(is);
            is->last_vis_time = time;
        }
        *remaining_time = FFMIN(*remaining_time, is->last_vis_time + rdftspeed - time);
    }

    if (is->video_st) {
retry:
        if (frame_queue_nb_remaining(&is->pictq) == 0) {
            // nothing to do, no picture to display in the queue
        } else {
            double last_duration, duration, delay;
            Frame *vp, *lastvp;

            /* dequeue the picture */
            lastvp = frame_queue_peek_last(&is->pictq);
            vp = frame_queue_peek(&is->pictq);

            if (vp->serial != is->videoq.serial) {
                frame_queue_next(&is->pictq);
                goto retry;
            }

            if (lastvp->serial != vp->serial)
                is->frame_timer = av_gettime_relative() / 1000000.0;

            if (is->paused)
                goto display;

            /* compute nominal last_duration */
            last_duration = vp_duration(is, lastvp, vp);
            delay = compute_target_delay(last_duration, is);

            time= av_gettime_relative()/1000000.0;
            if (time < is->frame_timer + delay) {
                *remaining_time = FFMIN(is->frame_timer + delay - time, *remaining_time);
                goto display;
            }

            is->frame_timer += delay;
            if (delay > 0 && time - is->frame_timer > AV_SYNC_THRESHOLD_MAX)
                is->frame_timer = time;

            SDL_LockMutex(is->pictq.mutex);
            if (!isnan(vp->pts))
                update_video_pts(is, vp->pts, vp->pos, vp->serial);
            SDL_UnlockMutex(is->pictq.mutex);

            if (frame_queue_nb_remaining(&is->pictq) > 1) {
                Frame *nextvp = frame_queue_peek_next(&is->pictq);
                duration = vp_duration(is, vp, nextvp);
                if(!is->step && (framedrop>0 || (framedrop && get_master_sync_type(is) != AV_SYNC_VIDEO_MASTER)) && time > is->frame_timer + duration){
                    is->frame_drops_late++;
                    frame_queue_next(&is->pictq);
                    goto retry;
                }
            }

            if (is->subtitle_st) {
                    while (frame_queue_nb_remaining(&is->subpq) > 0) {
                        sp = frame_queue_peek(&is->subpq);

                        if (frame_queue_nb_remaining(&is->subpq) > 1)
                            sp2 = frame_queue_peek_next(&is->subpq);
                        else
                            sp2 = NULL;

                        if (sp->serial != is->subtitleq.serial
                                || (is->vidclk.pts > (sp->pts + ((float) sp->sub.end_display_time / 1000)))
                                || (sp2 && is->vidclk.pts > (sp2->pts + ((float) sp2->sub.start_display_time / 1000))))
                        {
                            if (sp->uploaded) {
                                int i;
                                for (i = 0; i < sp->sub.num_rects; i++) {
                                    AVSubtitleRect *sub_rect = sp->sub.rects[i];
                                    uint8_t *pixels;
                                    int pitch, j;

                                    if (!SDL_LockTexture(is->sub_texture, (SDL_Rect *)sub_rect, (void **)&pixels, &pitch)) {
                                        for (j = 0; j < sub_rect->h; j++, pixels += pitch)
                                            memset(pixels, 0, sub_rect->w << 2);
                                        SDL_UnlockTexture(is->sub_texture);
                                    }
                                }
                            }
                            frame_queue_next(&is->subpq);
                        } else {
                            break;
                        }
                    }
            }

            frame_queue_next(&is->pictq);
            is->force_refresh = 1;

            if (is->step && !is->paused)
                stream_toggle_pause(is);
        }
display:
        /* display picture */
        if (!display_disable && is->force_refresh && is->show_mode == SHOW_MODE_VIDEO && is->pictq.rindex_shown)
            video_display(is);
    }
    is->force_refresh = 0;
    if (show_status) {
        static int64_t last_time;
        int64_t cur_time;
        int aqsize, vqsize, sqsize;
        double av_diff;

        cur_time = av_gettime_relative();
        if (!last_time || (cur_time - last_time) >= 30000) {
            aqsize = 0;
            vqsize = 0;
            sqsize = 0;
            if (is->audio_st)
                aqsize = is->audioq.size;
            if (is->video_st)
                vqsize = is->videoq.size;
            if (is->subtitle_st)
                sqsize = is->subtitleq.size;
            av_diff = 0;
            if (is->audio_st && is->video_st)
                av_diff = get_clock(&is->audclk) - get_clock(&is->vidclk);
            else if (is->video_st)
                av_diff = get_master_clock(is) - get_clock(&is->vidclk);
            else if (is->audio_st)
                av_diff = get_master_clock(is) - get_clock(&is->audclk);
            av_log(NULL, AV_LOG_INFO,
                   "%7.2f %s:%7.3f fd=%4d aq=%5dKB vq=%5dKB sq=%5dB f=%lld/%lld   \r",
                   get_master_clock(is),
                   (is->audio_st && is->video_st) ? "A-V" : (is->video_st ? "M-V" : (is->audio_st ? "M-A" : "   ")),
                   av_diff,
                   is->frame_drops_early + is->frame_drops_late,
                   aqsize / 1024,
                   vqsize / 1024,
                   sqsize,
                   is->video_st ? is->viddec.avctx->pts_correction_num_faulty_dts : 0,
                   is->video_st ? is->viddec.avctx->pts_correction_num_faulty_pts : 0);
            fflush(stdout);
            last_time = cur_time;
        }
    }
}

static int queue_picture(VideoState *is, AVFrame *src_frame, double pts, double duration, int64_t pos, int serial)
{
    Frame *vp;

#if defined(DEBUG_SYNC)
    printf("frame_type=%c pts=%0.3f\n",
           av_get_picture_type_char(src_frame->pict_type), pts);
#endif

    if (!(vp = frame_queue_peek_writable(&is->pictq)))
        return -1;

    vp->sar = src_frame->sample_aspect_ratio;
    vp->uploaded = 0;

    vp->width = src_frame->width;
    vp->height = src_frame->height;
    vp->format = src_frame->format;

    vp->pts = pts;
    vp->duration = duration;
    vp->pos = pos;
    vp->serial = serial;

    set_default_window_size(vp->width, vp->height, vp->sar);

    av_frame_move_ref(vp->frame, src_frame);
    frame_queue_push(&is->pictq);
    return 0;
}

static int get_video_frame(VideoState *is, AVFrame *frame)
{
    int got_picture;

    if ((got_picture = decoder_decode_frame(&is->viddec, frame, NULL)) < 0)
        return -1;

    if (got_picture) {
        double dpts = NAN;

        if (frame->pts != AV_NOPTS_VALUE)
            dpts = av_q2d(is->video_st->time_base) * frame->pts;

        frame->sample_aspect_ratio = av_guess_sample_aspect_ratio(is->ic, is->video_st, frame);

        if (framedrop>0 || (framedrop && get_master_sync_type(is) != AV_SYNC_VIDEO_MASTER)) {
            if (frame->pts != AV_NOPTS_VALUE) {
                double diff = dpts - get_master_clock(is);
                if (!isnan(diff) && fabs(diff) < AV_NOSYNC_THRESHOLD &&
                    diff - is->frame_last_filter_delay < 0 &&
                    is->viddec.pkt_serial == is->vidclk.serial &&
                    is->videoq.nb_packets) {
                    is->frame_drops_early++;
                    av_frame_unref(frame);
                    got_picture = 0;
                }
            }
        }
    }

    return got_picture;
}

#if CONFIG_AVFILTER
static int configure_filtergraph(AVFilterGraph *graph, const char *filtergraph,
                                 AVFilterContext *source_ctx, AVFilterContext *sink_ctx)
{
    int ret, i;
    int nb_filters = graph->nb_filters;
    AVFilterInOut *outputs = NULL, *inputs = NULL;

    if (filtergraph) {
        outputs = avfilter_inout_alloc();
        inputs  = avfilter_inout_alloc();
        if (!outputs || !inputs) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }

        outputs->name       = av_strdup("in");
        outputs->filter_ctx = source_ctx;
        outputs->pad_idx    = 0;
        outputs->next       = NULL;

        inputs->name        = av_strdup("out");
        inputs->filter_ctx  = sink_ctx;
        inputs->pad_idx     = 0;
        inputs->next        = NULL;

        if ((ret = avfilter_graph_parse_ptr(graph, filtergraph, &inputs, &outputs, NULL)) < 0)
            goto fail;
    } else {
        if ((ret = avfilter_link(source_ctx, 0, sink_ctx, 0)) < 0)
            goto fail;
    }

    /* Reorder the filters to ensure that inputs of the custom filters are merged first */
    for (i = 0; i < graph->nb_filters - nb_filters; i++)
        FFSWAP(AVFilterContext*, graph->filters[i], graph->filters[i + nb_filters]);

    ret = avfilter_graph_config(graph, NULL);
fail:
    avfilter_inout_free(&outputs);
    avfilter_inout_free(&inputs);
    return ret;
}

static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const char *vfilters, AVFrame *frame)
{
    static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_BGRA, AV_PIX_FMT_NONE };
    char sws_flags_str[512] = "";
    char buffersrc_args[256];
    int ret;
    AVFilterContext *filt_src = NULL, *filt_out = NULL, *last_filter = NULL;
    AVCodecParameters *codecpar = is->video_st->codecpar;
    AVRational fr = av_guess_frame_rate(is->ic, is->video_st, NULL);
    AVDictionaryEntry *e = NULL;

    while ((e = av_dict_get(sws_dict, "", e, AV_DICT_IGNORE_SUFFIX))) {
        if (!strcmp(e->key, "sws_flags")) {
            av_strlcatf(sws_flags_str, sizeof(sws_flags_str), "%s=%s:", "flags", e->value);
        } else
            av_strlcatf(sws_flags_str, sizeof(sws_flags_str), "%s=%s:", e->key, e->value);
    }
    if (strlen(sws_flags_str))
        sws_flags_str[strlen(sws_flags_str)-1] = '\0';

    graph->scale_sws_opts = av_strdup(sws_flags_str);

    snprintf(buffersrc_args, sizeof(buffersrc_args),
             "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
             frame->width, frame->height, frame->format,
             is->video_st->time_base.num, is->video_st->time_base.den,
             codecpar->sample_aspect_ratio.num, FFMAX(codecpar->sample_aspect_ratio.den, 1));
    if (fr.num && fr.den)
        av_strlcatf(buffersrc_args, sizeof(buffersrc_args), ":frame_rate=%d/%d", fr.num, fr.den);

    if ((ret = avfilter_graph_create_filter(&filt_src,
                                            avfilter_get_by_name("buffer"),
                                            "ffplay_buffer", buffersrc_args, NULL,
                                            graph)) < 0)
        goto fail;

    ret = avfilter_graph_create_filter(&filt_out,
                                       avfilter_get_by_name("buffersink"),
                                       "ffplay_buffersink", NULL, NULL, graph);
    if (ret < 0)
        goto fail;

    if ((ret = av_opt_set_int_list(filt_out, "pix_fmts", pix_fmts,  AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN)) < 0)
        goto fail;

    last_filter = filt_out;

/* Note: this macro adds a filter before the lastly added filter, so the
 * processing order of the filters is in reverse */
#define INSERT_FILT(name, arg) do {                                          \
    AVFilterContext *filt_ctx;                                               \
                                                                             \
    ret = avfilter_graph_create_filter(&filt_ctx,                            \
                                       avfilter_get_by_name(name),           \
                                       "ffplay_" name, arg, NULL, graph);    \
    if (ret < 0)                                                             \
        goto fail;                                                           \
                                                                             \
    ret = avfilter_link(filt_ctx, 0, last_filter, 0);                        \
    if (ret < 0)                                                             \
        goto fail;                                                           \
                                                                             \
    last_filter = filt_ctx;                                                  \
} while (0)

    if (autorotate) {
        double theta  = get_rotation(is->video_st);

        if (fabs(theta - 90) < 1.0) {
            INSERT_FILT("transpose", "clock");
        } else if (fabs(theta - 180) < 1.0) {
            INSERT_FILT("hflip", NULL);
            INSERT_FILT("vflip", NULL);
        } else if (fabs(theta - 270) < 1.0) {
            INSERT_FILT("transpose", "cclock");
        } else if (fabs(theta) > 1.0) {
            char rotate_buf[64];
            snprintf(rotate_buf, sizeof(rotate_buf), "%f*PI/180", theta);
            INSERT_FILT("rotate", rotate_buf);
        }
    }

    if ((ret = configure_filtergraph(graph, vfilters, filt_src, last_filter)) < 0)
        goto fail;

    is->in_video_filter  = filt_src;
    is->out_video_filter = filt_out;

fail:
    return ret;
}

static int configure_audio_filters(VideoState *is, const char *afilters, int force_output_format)
{
    static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE };
    int sample_rates[2] = { 0, -1 };
    int64_t channel_layouts[2] = { 0, -1 };
    int channels[2] = { 0, -1 };
    AVFilterContext *filt_asrc = NULL, *filt_asink = NULL;
    char aresample_swr_opts[512] = "";
    AVDictionaryEntry *e = NULL;
    char asrc_args[256];
    int ret;

    avfilter_graph_free(&is->agraph);
    if (!(is->agraph = avfilter_graph_alloc()))
        return AVERROR(ENOMEM);

    while ((e = av_dict_get(swr_opts, "", e, AV_DICT_IGNORE_SUFFIX)))
        av_strlcatf(aresample_swr_opts, sizeof(aresample_swr_opts), "%s=%s:", e->key, e->value);
    if (strlen(aresample_swr_opts))
        aresample_swr_opts[strlen(aresample_swr_opts)-1] = '\0';
    av_opt_set(is->agraph, "aresample_swr_opts", aresample_swr_opts, 0);

    ret = snprintf(asrc_args, sizeof(asrc_args),
                   "sample_rate=%d:sample_fmt=%s:channels=%d:time_base=%d/%d",
                   is->audio_filter_src.freq, av_get_sample_fmt_name(is->audio_filter_src.fmt),
                   is->audio_filter_src.channels,
                   1, is->audio_filter_src.freq);
    if (is->audio_filter_src.channel_layout)
        snprintf(asrc_args + ret, sizeof(asrc_args) - ret,
                 ":channel_layout=0x%x",  is->audio_filter_src.channel_layout);

    ret = avfilter_graph_create_filter(&filt_asrc,
                                       avfilter_get_by_name("abuffer"), "ffplay_abuffer",
                                       asrc_args, NULL, is->agraph);
    if (ret < 0)
        goto end;


    ret = avfilter_graph_create_filter(&filt_asink,
                                       avfilter_get_by_name("abuffersink"), "ffplay_abuffersink",
                                       NULL, NULL, is->agraph);
    if (ret < 0)
        goto end;

    if ((ret = av_opt_set_int_list(filt_asink, "sample_fmts", sample_fmts,  AV_SAMPLE_FMT_NONE, AV_OPT_SEARCH_CHILDREN)) < 0)
        goto end;
    if ((ret = av_opt_set_int(filt_asink, "all_channel_counts", 1, AV_OPT_SEARCH_CHILDREN)) < 0)
        goto end;

    if (force_output_format) {
        channel_layouts[0] = is->audio_tgt.channel_layout;
        channels       [0] = is->audio_tgt.channels;
        sample_rates   [0] = is->audio_tgt.freq;
        if ((ret = av_opt_set_int(filt_asink, "all_channel_counts", 0, AV_OPT_SEARCH_CHILDREN)) < 0)
            goto end;
        if ((ret = av_opt_set_int_list(filt_asink, "channel_layouts", channel_layouts,  -1, AV_OPT_SEARCH_CHILDREN)) < 0)
            goto end;
        if ((ret = av_opt_set_int_list(filt_asink, "channel_counts" , channels       ,  -1, AV_OPT_SEARCH_CHILDREN)) < 0)
            goto end;
        if ((ret = av_opt_set_int_list(filt_asink, "sample_rates"   , sample_rates   ,  -1, AV_OPT_SEARCH_CHILDREN)) < 0)
            goto end;
    }


    if ((ret = configure_filtergraph(is->agraph, afilters, filt_asrc, filt_asink)) < 0)
        goto end;

    is->in_audio_filter  = filt_asrc;
    is->out_audio_filter = filt_asink;

end:
    if (ret < 0)
        avfilter_graph_free(&is->agraph);
    return ret;
}
#endif  /* CONFIG_AVFILTER */

static int audio_thread(void *arg)
{
    VideoState *is = (VideoState *)arg;
    AVFrame *frame = av_frame_alloc();
    Frame *af;
#if CONFIG_AVFILTER
    int last_serial = -1;
    int64_t dec_channel_layout;
    int reconfigure;
#endif
    int got_frame = 0;
    AVRational tb;
    int ret = 0;

    if (!frame)
        return AVERROR(ENOMEM);

    do {
        if ((got_frame = decoder_decode_frame(&is->auddec, frame, NULL)) < 0)
            goto the_end;

        if (got_frame) {
                tb = (AVRational){1, frame->sample_rate};

#if CONFIG_AVFILTER
                dec_channel_layout = get_valid_channel_layout(frame->channel_layout, av_frame_get_channels(frame));

                reconfigure =
                    cmp_audio_fmts(is->audio_filter_src.fmt, is->audio_filter_src.channels,
                                   (enum AVSampleFormat)frame->format, av_frame_get_channels(frame))    ||
                    is->audio_filter_src.channel_layout != dec_channel_layout ||
                    is->audio_filter_src.freq           != frame->sample_rate ||
                    is->auddec.pkt_serial               != last_serial;

                if (reconfigure) {
                    char buf1[1024], buf2[1024];
                    av_get_channel_layout_string(buf1, sizeof(buf1), -1, is->audio_filter_src.channel_layout);
                    av_get_channel_layout_string(buf2, sizeof(buf2), -1, dec_channel_layout);
                    av_log(NULL, AV_LOG_DEBUG,
                           "Audio frame changed from rate:%d ch:%d fmt:%s layout:%s serial:%d to rate:%d ch:%d fmt:%s layout:%s serial:%d\n",
                           is->audio_filter_src.freq, is->audio_filter_src.channels, av_get_sample_fmt_name(is->audio_filter_src.fmt), buf1, last_serial,
                           frame->sample_rate, av_frame_get_channels(frame), av_get_sample_fmt_name((enum AVSampleFormat)frame->format), buf2, is->auddec.pkt_serial);

                    is->audio_filter_src.fmt            = (enum AVSampleFormat)frame->format;
                    is->audio_filter_src.channels       = av_frame_get_channels(frame);
                    is->audio_filter_src.channel_layout = dec_channel_layout;
                    is->audio_filter_src.freq           = frame->sample_rate;
                    last_serial                         = is->auddec.pkt_serial;

                    if ((ret = configure_audio_filters(is, afilters, 1)) < 0)
                        goto the_end;
                }

            if ((ret = av_buffersrc_add_frame(is->in_audio_filter, frame)) < 0)
                goto the_end;

            while ((ret = av_buffersink_get_frame_flags(is->out_audio_filter, frame, 0)) >= 0) {
                tb = av_buffersink_get_time_base(is->out_audio_filter);
#endif
                // audio pcm队列
                if (!(af = frame_queue_peek_writable(&is->sampq)))
                    goto the_end;
                // 有可写入的位置
                af->pts = (frame->pts == AV_NOPTS_VALUE) ? NAN : frame->pts * av_q2d(tb);	// 转换pts? 转成成秒?
                af->pos = av_frame_get_pkt_pos(frame);
                af->serial = is->auddec.pkt_serial;
                af->duration = av_q2d((AVRational){frame->nb_samples, frame->sample_rate});	// 持续时间

                av_frame_move_ref(af->frame, frame);		// 转移frame, 原来的frame被重置
                frame_queue_push(&is->sampq);				// 这里才真正如队列

#if CONFIG_AVFILTER
                if (is->audioq.serial != is->auddec.pkt_serial)
                    break;
            }
            if (ret == AVERROR_EOF)
                is->auddec.finished = is->auddec.pkt_serial;
#endif
        }
    } while (ret >= 0 || ret == AVERROR(EAGAIN) || ret == AVERROR_EOF);
 the_end:
#if CONFIG_AVFILTER
    avfilter_graph_free(&is->agraph);
#endif
    av_frame_free(&frame);
    return ret;
}

/**
* 创建解码线程, audio/video/Subtitle都有独立的线程
*/
static int decoder_start(Decoder *d, int (*fn)(void *), void *arg)
{
    packet_queue_start(d->queue);
    d->decoder_tid = SDL_CreateThread(fn, "decoder", arg);
    if (!d->decoder_tid) {
        av_log(NULL, AV_LOG_ERROR, "SDL_CreateThread(): %s\n", SDL_GetError());
        return AVERROR(ENOMEM);
    }
    return 0;
}

static int video_thread(void *arg)
{
    VideoState *is = (VideoState *)arg;
    AVFrame *frame = av_frame_alloc();
    double pts;
    double duration;
    int ret;
    AVRational tb = is->video_st->time_base;
    AVRational frame_rate = av_guess_frame_rate(is->ic, is->video_st, NULL);

#if CONFIG_AVFILTER
    AVFilterGraph *graph = avfilter_graph_alloc();
    AVFilterContext *filt_out = NULL, *filt_in = NULL;
    int last_w = 0;
    int last_h = 0;
    enum AVPixelFormat last_format = (enum AVPixelFormat)-2;
    int last_serial = -1;
    int last_vfilter_idx = 0;
    if (!graph) {
        av_frame_free(&frame);
        return AVERROR(ENOMEM);
    }

#endif

    if (!frame) {
#if CONFIG_AVFILTER
        avfilter_graph_free(&graph);
#endif
        return AVERROR(ENOMEM);
    }

    for (;;) {
        ret = get_video_frame(is, frame);
        if (ret < 0)
            goto the_end;
        if (!ret)
            continue;

#if CONFIG_AVFILTER
        if (   last_w != frame->width
            || last_h != frame->height
            || last_format != frame->format
            || last_serial != is->viddec.pkt_serial
            || last_vfilter_idx != is->vfilter_idx) {
            av_log(NULL, AV_LOG_DEBUG,
                   "Video frame changed from size:%dx%d format:%s serial:%d to size:%dx%d format:%s serial:%d\n",
                   last_w, last_h,
                   (const char *)av_x_if_null(av_get_pix_fmt_name(last_format), "none"), last_serial,
                   frame->width, frame->height,
                   (const char *)av_x_if_null(av_get_pix_fmt_name((enum AVPixelFormat)frame->format), "none"), is->viddec.pkt_serial);
            avfilter_graph_free(&graph);
            graph = avfilter_graph_alloc();
            if ((ret = configure_video_filters(graph, is, vfilters_list ? vfilters_list[is->vfilter_idx] : NULL, frame)) < 0) {
                SDL_Event event;
                event.type = FF_QUIT_EVENT;
                event.user.data1 = is;
                SDL_PushEvent(&event);
                goto the_end;
            }
            filt_in  = is->in_video_filter;
            filt_out = is->out_video_filter;
            last_w = frame->width;
            last_h = frame->height;
            last_format = (enum AVPixelFormat)frame->format;
            last_serial = is->viddec.pkt_serial;
            last_vfilter_idx = is->vfilter_idx;
            frame_rate = av_buffersink_get_frame_rate(filt_out);
        }

        ret = av_buffersrc_add_frame(filt_in, frame);
        if (ret < 0)
            goto the_end;

        while (ret >= 0) {
            is->frame_last_returned_time = av_gettime_relative() / 1000000.0;

            ret = av_buffersink_get_frame_flags(filt_out, frame, 0);
            if (ret < 0) {
                if (ret == AVERROR_EOF)
                    is->viddec.finished = is->viddec.pkt_serial;
                ret = 0;
                break;
            }

            is->frame_last_filter_delay = av_gettime_relative() / 1000000.0 - is->frame_last_returned_time;
            if (fabs(is->frame_last_filter_delay) > AV_NOSYNC_THRESHOLD / 10.0)
                is->frame_last_filter_delay = 0;
            tb = av_buffersink_get_time_base(filt_out);
#endif
            duration = (frame_rate.num && frame_rate.den ? av_q2d((AVRational){frame_rate.den, frame_rate.num}) : 0);
            pts = (frame->pts == AV_NOPTS_VALUE) ? NAN : frame->pts * av_q2d(tb);
            ret = queue_picture(is, frame, pts, duration, av_frame_get_pkt_pos(frame), is->viddec.pkt_serial);
            av_frame_unref(frame);
#if CONFIG_AVFILTER
        }
#endif

        if (ret < 0)
            goto the_end;
    }
 the_end:
#if CONFIG_AVFILTER
    avfilter_graph_free(&graph);
#endif
    av_frame_free(&frame);
    return 0;
}

static int subtitle_thread(void *arg)
{
    VideoState *is = (VideoState *)arg;
    Frame *sp;
    int got_subtitle;
    double pts;

    for (;;) {
        if (!(sp = frame_queue_peek_writable(&is->subpq)))
            return 0;

        if ((got_subtitle = decoder_decode_frame(&is->subdec, NULL, &sp->sub)) < 0)
            break;

        pts = 0;

        if (got_subtitle && sp->sub.format == 0) {
            if (sp->sub.pts != AV_NOPTS_VALUE)
                pts = sp->sub.pts / (double)AV_TIME_BASE;
            sp->pts = pts;
            sp->serial = is->subdec.pkt_serial;
            sp->width = is->subdec.avctx->width;
            sp->height = is->subdec.avctx->height;
            sp->uploaded = 0;

            /* now we can update the picture count */
            frame_queue_push(&is->subpq);
        } else if (got_subtitle) {
            avsubtitle_free(&sp->sub);
        }
    }
    return 0;
}

/* copy samples for viewing in editor window */
static void update_sample_display(VideoState *is, short *samples, int samples_size)
{
    int size, len;

    size = samples_size / sizeof(short);
    while (size > 0) {
        len = SAMPLE_ARRAY_SIZE - is->sample_array_index;
        if (len > size)
            len = size;
        memcpy(is->sample_array + is->sample_array_index, samples, len * sizeof(short));
        samples += len;
        is->sample_array_index += len;
        if (is->sample_array_index >= SAMPLE_ARRAY_SIZE)
            is->sample_array_index = 0;
        size -= len;
    }
}

/* return the wanted number of samples to get better sync if sync_type is video
 * or external master clock */
static int synchronize_audio(VideoState *is, int nb_samples)
{
    int wanted_nb_samples = nb_samples;

    /* if not master, then we try to remove or add samples to correct the clock */
    if (get_master_sync_type(is) != AV_SYNC_AUDIO_MASTER) {
        double diff, avg_diff;
        int min_nb_samples, max_nb_samples;

        diff = get_clock(&is->audclk) - get_master_clock(is);

        if (!isnan(diff) && fabs(diff) < AV_NOSYNC_THRESHOLD) {
            is->audio_diff_cum = diff + is->audio_diff_avg_coef * is->audio_diff_cum;
            if (is->audio_diff_avg_count < AUDIO_DIFF_AVG_NB) {
                /* not enough measures to have a correct estimate */
                is->audio_diff_avg_count++;
            } else {
                /* estimate the A-V difference */
                avg_diff = is->audio_diff_cum * (1.0 - is->audio_diff_avg_coef);

                if (fabs(avg_diff) >= is->audio_diff_threshold) {
                    wanted_nb_samples = nb_samples + (int)(diff * is->audio_src.freq);
                    min_nb_samples = ((nb_samples * (100 - SAMPLE_CORRECTION_PERCENT_MAX) / 100));
                    max_nb_samples = ((nb_samples * (100 + SAMPLE_CORRECTION_PERCENT_MAX) / 100));
                    wanted_nb_samples = av_clip(wanted_nb_samples, min_nb_samples, max_nb_samples);
                }
                av_log(NULL, AV_LOG_TRACE, "diff=%f adiff=%f sample_diff=%d apts=%0.3f %f\n",
                        diff, avg_diff, wanted_nb_samples - nb_samples,
                        is->audio_clock, is->audio_diff_threshold);
            }
        } else {
            /* too big difference : may be initial PTS errors, so
               reset A-V filter */
            is->audio_diff_avg_count = 0;
            is->audio_diff_cum       = 0;
        }
    }

    return wanted_nb_samples;
}

/**
 * Decode one audio frame and return its uncompressed size.
 *
 * The processed audio frame is decoded, converted if required, and
 * stored in is->audio_buf, with size in bytes given by the return
 * value.
 */
static int audio_decode_frame(VideoState *is)
{
    int data_size, resampled_data_size;
    int64_t dec_channel_layout;
    av_unused double audio_clock0;
    int wanted_nb_samples;
    Frame *af;

    if (is->paused)
        return -1;

    do {
#if defined(_WIN32)
        while (frame_queue_nb_remaining(&is->sampq) == 0) {
            if ((av_gettime_relative() - audio_callback_time) > 1000000LL * is->audio_hw_buf_size / is->audio_tgt.bytes_per_sec / 2)
                return -1;
            av_usleep (1000);
        }
#endif
        if (!(af = frame_queue_peek_readable(&is->sampq)))		// 取出一帧数据
            return -1;
        frame_queue_next(&is->sampq);
    } while (af->serial != is->audioq.serial);

    data_size = av_samples_get_buffer_size(NULL, av_frame_get_channels(af->frame),
                                           af->frame->nb_samples,
                                           (enum AVSampleFormat)af->frame->format, 1);

    dec_channel_layout =
        (af->frame->channel_layout && av_frame_get_channels(af->frame) == av_get_channel_layout_nb_channels(af->frame->channel_layout)) ?
        af->frame->channel_layout : av_get_default_channel_layout(av_frame_get_channels(af->frame));
    wanted_nb_samples = synchronize_audio(is, af->frame->nb_samples);

    // 初始化sample格式转换器
    if (af->frame->format        != is->audio_src.fmt            ||
        dec_channel_layout       != is->audio_src.channel_layout ||
        af->frame->sample_rate   != is->audio_src.freq           ||
        (wanted_nb_samples       != af->frame->nb_samples && !is->swr_ctx)) {
        swr_free(&is->swr_ctx);
        is->swr_ctx = swr_alloc_set_opts(NULL,
                                         is->audio_tgt.channel_layout, is->audio_tgt.fmt, is->audio_tgt.freq,
                                         dec_channel_layout,   (enum AVSampleFormat)af->frame->format, af->frame->sample_rate,
                                         0, NULL);
        if (!is->swr_ctx || swr_init(is->swr_ctx) < 0) {
            av_log(NULL, AV_LOG_ERROR,
                   "Cannot create sample rate converter for conversion of %d Hz %s %d channels to %d Hz %s %d channels!\n",
                    af->frame->sample_rate, av_get_sample_fmt_name((enum AVSampleFormat)af->frame->format), av_frame_get_channels(af->frame),
                    is->audio_tgt.freq, av_get_sample_fmt_name(is->audio_tgt.fmt), is->audio_tgt.channels);
            swr_free(&is->swr_ctx);
            return -1;
        }
        is->audio_src.channel_layout = dec_channel_layout;
        is->audio_src.channels       = av_frame_get_channels(af->frame);
        is->audio_src.freq = af->frame->sample_rate;
        is->audio_src.fmt = (enum AVSampleFormat)af->frame->format;
    }

    if (is->swr_ctx) {
        const uint8_t **in = (const uint8_t **)af->frame->extended_data;
        uint8_t **out = &is->audio_buf1;
        int out_count = (int64_t)wanted_nb_samples * is->audio_tgt.freq / af->frame->sample_rate + 256;
        int out_size  = av_samples_get_buffer_size(NULL, is->audio_tgt.channels, out_count, is->audio_tgt.fmt, 0);
        int len2;
        if (out_size < 0) {
            av_log(NULL, AV_LOG_ERROR, "av_samples_get_buffer_size() failed\n");
            return -1;
        }
        if (wanted_nb_samples != af->frame->nb_samples) {
            if (swr_set_compensation(is->swr_ctx, (wanted_nb_samples - af->frame->nb_samples) * is->audio_tgt.freq / af->frame->sample_rate,
                                        wanted_nb_samples * is->audio_tgt.freq / af->frame->sample_rate) < 0) {
                av_log(NULL, AV_LOG_ERROR, "swr_set_compensation() failed\n");
                return -1;
            }
        }
        av_fast_malloc(&is->audio_buf1, &is->audio_buf1_size, out_size);
        if (!is->audio_buf1)
            return AVERROR(ENOMEM);
        len2 = swr_convert(is->swr_ctx, out, out_count, in, af->frame->nb_samples);
        if (len2 < 0) {
            av_log(NULL, AV_LOG_ERROR, "swr_convert() failed\n");
            return -1;
        }
        if (len2 == out_count) {
            av_log(NULL, AV_LOG_WARNING, "audio buffer is probably too small\n");
            if (swr_init(is->swr_ctx) < 0)
                swr_free(&is->swr_ctx);
        }
        is->audio_buf = is->audio_buf1;
        resampled_data_size = len2 * is->audio_tgt.channels * av_get_bytes_per_sample(is->audio_tgt.fmt);
    } else {
        is->audio_buf = af->frame->data[0];
        resampled_data_size = data_size;
    }

    audio_clock0 = is->audio_clock;
    /* update the audio clock with the pts */
    if (!isnan(af->pts))
        is->audio_clock = af->pts + (double) af->frame->nb_samples / af->frame->sample_rate;
    else
        is->audio_clock = NAN;
    is->audio_clock_serial = af->serial;
#ifdef DEBUG
    {
        static double last_clock;
        printf("audio: delay=%0.3f clock=%0.3f clock0=%0.3f\n",
               is->audio_clock - last_clock,
               is->audio_clock, audio_clock0);
        last_clock = is->audio_clock;
    }
#endif
    return resampled_data_size;
}

/* prepare a new audio buffer */
static void sdl_audio_callback(void *opaque, Uint8 *stream, int len)
{
    VideoState *is = (VideoState *)opaque;
    int audio_size, len1;

    audio_callback_time = av_gettime_relative();

    while (len > 0) {
        if (is->audio_buf_index >= is->audio_buf_size) {
           audio_size = audio_decode_frame(is);
           if (audio_size < 0) {
                /* if error, just output silence */
               is->audio_buf = NULL;
               is->audio_buf_size = SDL_AUDIO_MIN_BUFFER_SIZE / is->audio_tgt.frame_size * is->audio_tgt.frame_size;
           } else {
               if (is->show_mode != SHOW_MODE_VIDEO)
                   update_sample_display(is, (int16_t *)is->audio_buf, audio_size);
               is->audio_buf_size = audio_size;
           }
           is->audio_buf_index = 0;
        }
        len1 = is->audio_buf_size - is->audio_buf_index;
        if (len1 > len)
            len1 = len;
        if (!is->muted && is->audio_buf && is->audio_volume == SDL_MIX_MAXVOLUME)
            memcpy(stream, (uint8_t *)is->audio_buf + is->audio_buf_index, len1);
        else {
            memset(stream, 0, len1);
            if (!is->muted && is->audio_buf)
                SDL_MixAudio(stream, (uint8_t *)is->audio_buf + is->audio_buf_index, len1, is->audio_volume);
        }
        len -= len1;
        stream += len1;
        is->audio_buf_index += len1;
    }
    is->audio_write_buf_size = is->audio_buf_size - is->audio_buf_index;
    /* Let's assume the audio driver that is used by SDL has two periods. */
    if (!isnan(is->audio_clock)) {
        set_clock_at(&is->audclk, is->audio_clock - (double)(2 * is->audio_hw_buf_size + is->audio_write_buf_size) / is->audio_tgt.bytes_per_sec, is->audio_clock_serial, audio_callback_time / 1000000.0);
        sync_clock_to_slave(&is->extclk, &is->audclk);
    }
}

static int audio_open(void *opaque, int64_t wanted_channel_layout, int wanted_nb_channels, int wanted_sample_rate, struct AudioParams *audio_hw_params)
{
    SDL_AudioSpec wanted_spec, spec;
    const char *env;
    static const int next_nb_channels[] = {0, 0, 1, 6, 2, 6, 4, 6};
    static const int next_sample_rates[] = {0, 44100, 48000, 96000, 192000};
    int next_sample_rate_idx = FF_ARRAY_ELEMS(next_sample_rates) - 1;

    // 如果不移到这里初始化,SDL_OpenAudio打开失败,为什么呢?
    if (SDL_Init (SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        av_log(NULL, AV_LOG_FATAL, "Could not initialize SDL - %s\n", SDL_GetError());
        av_log(NULL, AV_LOG_FATAL, "(Did you set the DISPLAY variable?)\n");
        exit(1);
    }

    env = SDL_getenv("SDL_AUDIO_CHANNELS");
    if (env) {
        wanted_nb_channels = atoi(env);
        wanted_channel_layout = av_get_default_channel_layout(wanted_nb_channels);
    }
    if (!wanted_channel_layout || wanted_nb_channels != av_get_channel_layout_nb_channels(wanted_channel_layout)) {
        wanted_channel_layout = av_get_default_channel_layout(wanted_nb_channels);
        wanted_channel_layout &= ~AV_CH_LAYOUT_STEREO_DOWNMIX;
    }
    wanted_nb_channels = av_get_channel_layout_nb_channels(wanted_channel_layout);
    wanted_spec.channels = wanted_nb_channels;
    wanted_spec.freq = wanted_sample_rate;
    if (wanted_spec.freq <= 0 || wanted_spec.channels <= 0) {
        av_log(NULL, AV_LOG_ERROR, "Invalid sample rate or channel count!\n");
        return -1;
    }
    while (next_sample_rate_idx && next_sample_rates[next_sample_rate_idx] >= wanted_spec.freq)
        next_sample_rate_idx--;
    wanted_spec.format = AUDIO_S16SYS;
    wanted_spec.silence = 0;
    wanted_spec.samples = FFMAX(SDL_AUDIO_MIN_BUFFER_SIZE, 2 << av_log2(wanted_spec.freq / SDL_AUDIO_MAX_CALLBACKS_PER_SEC));
    wanted_spec.callback = sdl_audio_callback;
    wanted_spec.userdata = opaque;

//    wanted_spec.format = AUDIO_S16SYS;
//    wanted_spec.silence = 0;
//     wanted_spec.samples = 1024;
//    wanted_spec.callback = sdl_audio_callback;
//    wanted_spec.userdata = opaque;
//    wanted_spec.channels = 2;
    putenv("SDL_AUDIODRIVER=DirectSound");

    while (SDL_OpenAudio(&wanted_spec, &spec) < 0) {
        av_log(NULL, AV_LOG_WARNING, "SDL_OpenAudio (%d channels, %d Hz): %s\n",
               wanted_spec.channels, wanted_spec.freq, SDL_GetError());
        wanted_spec.channels = next_nb_channels[FFMIN(7, wanted_spec.channels)];
        if (!wanted_spec.channels) {
            wanted_spec.freq = next_sample_rates[next_sample_rate_idx--];
            wanted_spec.channels = wanted_nb_channels;
            if (!wanted_spec.freq) {
                av_log(NULL, AV_LOG_ERROR,
                       "No more combinations to try, audio open failed\n");
                return -1;
            }
        }
        wanted_channel_layout = av_get_default_channel_layout(wanted_spec.channels);
    }
    if (spec.format != AUDIO_S16SYS) {
        av_log(NULL, AV_LOG_ERROR,
               "SDL advised audio format %d is not supported!\n", spec.format);
        return -1;
    }
    if (spec.channels != wanted_spec.channels) {
        wanted_channel_layout = av_get_default_channel_layout(spec.channels);
        if (!wanted_channel_layout) {
            av_log(NULL, AV_LOG_ERROR,
                   "SDL advised channel count %d is not supported!\n", spec.channels);
            return -1;
        }
    }

    audio_hw_params->fmt = AV_SAMPLE_FMT_S16;
    audio_hw_params->freq = spec.freq;
    audio_hw_params->channel_layout = wanted_channel_layout;
    audio_hw_params->channels =  spec.channels;
    audio_hw_params->frame_size = av_samples_get_buffer_size(NULL, audio_hw_params->channels, 1, audio_hw_params->fmt, 1);
    audio_hw_params->bytes_per_sec = av_samples_get_buffer_size(NULL, audio_hw_params->channels, audio_hw_params->freq, audio_hw_params->fmt, 1);
    if (audio_hw_params->bytes_per_sec <= 0 || audio_hw_params->frame_size <= 0) {
        av_log(NULL, AV_LOG_ERROR, "av_samples_get_buffer_size failed\n");
        return -1;
    }
    return spec.size;
}

/* open a given stream. Return 0 if OK */
static int stream_component_open(VideoState *is, int stream_index)
{
    AVFormatContext *ic = is->ic;
    AVCodecContext *avctx;
    AVCodec *codec;
    const char *forced_codec_name = NULL;
    AVDictionary *opts = NULL;
    AVDictionaryEntry *t = NULL;
    int sample_rate, nb_channels;
    int64_t channel_layout;
    int ret = 0;
    int stream_lowres = lowres;

    if (stream_index < 0 || stream_index >= ic->nb_streams)
        return -1;

    avctx = avcodec_alloc_context3(NULL);
    if (!avctx)
        return AVERROR(ENOMEM);

    ret = avcodec_parameters_to_context(avctx, ic->streams[stream_index]->codecpar);	// 初始化解码器参数
    if (ret < 0)
        goto fail;
    av_codec_set_pkt_timebase(avctx, ic->streams[stream_index]->time_base);				//

    codec = avcodec_find_decoder(avctx->codec_id);

    switch(avctx->codec_type){
        case AVMEDIA_TYPE_AUDIO   : is->last_audio_stream    = stream_index; forced_codec_name =    audio_codec_name; break;
        case AVMEDIA_TYPE_SUBTITLE: is->last_subtitle_stream = stream_index; forced_codec_name = subtitle_codec_name; break;
        case AVMEDIA_TYPE_VIDEO   : is->last_video_stream    = stream_index; forced_codec_name =    video_codec_name; break;
    }
    if (forced_codec_name)
        codec = avcodec_find_decoder_by_name(forced_codec_name);
    if (!codec) {
        if (forced_codec_name) av_log(NULL, AV_LOG_WARNING,
                                      "No codec could be found with name '%s'\n", forced_codec_name);
        else                   av_log(NULL, AV_LOG_WARNING,
                                      "No codec could be found with id %d\n", avctx->codec_id);
        ret = AVERROR(EINVAL);
        goto fail;
    }

    avctx->codec_id = codec->id;
    if(stream_lowres > av_codec_get_max_lowres(codec)){
        av_log(avctx, AV_LOG_WARNING, "The maximum value for lowres supported by the decoder is %d\n",
                av_codec_get_max_lowres(codec));
        stream_lowres = av_codec_get_max_lowres(codec);
    }
    av_codec_set_lowres(avctx, stream_lowres);

#if FF_API_EMU_EDGE
    if(stream_lowres) avctx->flags |= CODEC_FLAG_EMU_EDGE;
#endif
    if (fast)
        avctx->flags2 |= AV_CODEC_FLAG2_FAST;
#if FF_API_EMU_EDGE
    if(codec->capabilities & AV_CODEC_CAP_DR1)
        avctx->flags |= CODEC_FLAG_EMU_EDGE;
#endif

//    opts = filter_codec_opts(codec_opts, avctx->codec_id, ic, ic->streams[stream_index], codec);
    if (!av_dict_get(opts, "threads", NULL, 0))
        av_dict_set(&opts, "threads", "auto", 0);
    if (stream_lowres)
        av_dict_set_int(&opts, "lowres", stream_lowres, 0);
    if (avctx->codec_type == AVMEDIA_TYPE_VIDEO || avctx->codec_type == AVMEDIA_TYPE_AUDIO)
        av_dict_set(&opts, "refcounted_frames", "1", 0);
    if ((ret = avcodec_open2(avctx, codec, &opts)) < 0) {
        goto fail;
    }
    if ((t = av_dict_get(opts, "", NULL, AV_DICT_IGNORE_SUFFIX))) {
        av_log(NULL, AV_LOG_ERROR, "Option %s not found.\n", t->key);
        ret =  AVERROR_OPTION_NOT_FOUND;
        goto fail;
    }

    is->eof = 0;
    ic->streams[stream_index]->discard = AVDISCARD_DEFAULT;
    switch (avctx->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
#if CONFIG_AVFILTER
        {
            AVFilterContext *sink;

            is->audio_filter_src.freq           = avctx->sample_rate;
            is->audio_filter_src.channels       = avctx->channels;
            is->audio_filter_src.channel_layout = get_valid_channel_layout(avctx->channel_layout, avctx->channels);
            is->audio_filter_src.fmt            = avctx->sample_fmt;
            if ((ret = configure_audio_filters(is, afilters, 0)) < 0)
                goto fail;
            sink = is->out_audio_filter;
            sample_rate    = av_buffersink_get_sample_rate(sink);
            nb_channels    = av_buffersink_get_channels(sink);
            channel_layout = av_buffersink_get_channel_layout(sink);
        }
#else
        sample_rate    = avctx->sample_rate;
        nb_channels    = avctx->channels;
        channel_layout = avctx->channel_layout;
#endif

        /* prepare audio output */
        if ((ret = audio_open(is, channel_layout, nb_channels, sample_rate, &is->audio_tgt)) < 0)
            goto fail;
        is->audio_hw_buf_size = ret;
        is->audio_src = is->audio_tgt;
        is->audio_buf_size  = 0;
        is->audio_buf_index = 0;

        /* init averaging filter */
        is->audio_diff_avg_coef  = exp(log(0.01) / AUDIO_DIFF_AVG_NB);
        is->audio_diff_avg_count = 0;
        /* since we do not have a precise anough audio FIFO fullness,
           we correct audio sync only if larger than this threshold */
        is->audio_diff_threshold = (double)(is->audio_hw_buf_size) / is->audio_tgt.bytes_per_sec;

        is->audio_stream = stream_index;
        is->audio_st = ic->streams[stream_index];

        decoder_init(&is->auddec, avctx, &is->audioq, is->continue_read_thread);
        if ((is->ic->iformat->flags & (AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH | AVFMT_NO_BYTE_SEEK)) && !is->ic->iformat->read_seek) {
            is->auddec.start_pts = is->audio_st->start_time;
            is->auddec.start_pts_tb = is->audio_st->time_base;
        }
        if ((ret = decoder_start(&is->auddec, audio_thread, is)) < 0)
            goto out;
        SDL_PauseAudio(0);
        break;
    case AVMEDIA_TYPE_VIDEO:
        is->video_stream = stream_index;
        is->video_st = ic->streams[stream_index];

        decoder_init(&is->viddec, avctx, &is->videoq, is->continue_read_thread);
        if ((ret = decoder_start(&is->viddec, video_thread, is)) < 0)
            goto out;
        is->queue_attachments_req = 1;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        is->subtitle_stream = stream_index;
        is->subtitle_st = ic->streams[stream_index];

        decoder_init(&is->subdec, avctx, &is->subtitleq, is->continue_read_thread);
        if ((ret = decoder_start(&is->subdec, subtitle_thread, is)) < 0)
            goto out;
        break;
    default:
        break;
    }
    goto out;

fail:
    avcodec_free_context(&avctx);
out:
    av_dict_free(&opts);

    return ret;
}

static int decode_interrupt_cb(void *ctx)
{
    VideoState *is = (VideoState *)ctx;
    return is->abort_request;
}

static int stream_has_enough_packets(AVStream *st, int stream_id, PacketQueue *queue) {
    return stream_id < 0 ||
           queue->abort_request ||
           (st->disposition & AV_DISPOSITION_ATTACHED_PIC) ||
           queue->nb_packets > MIN_FRAMES && (!queue->duration || av_q2d(st->time_base) * queue->duration > 1.0);
}

static int is_realtime(AVFormatContext *s)
{
    if(   !strcmp(s->iformat->name, "rtp")
       || !strcmp(s->iformat->name, "rtsp")
       || !strcmp(s->iformat->name, "sdp")
    )
        return 1;

    if(s->pb && (   !strncmp(s->filename, "rtp:", 4)
                 || !strncmp(s->filename, "udp:", 4)
                )
    )
        return 1;
    return 0;
}

/* this thread gets the stream from the disk or the network */
// 数据都由这里读取
static int read_thread(void *arg)
{
    VideoState *is = (VideoState *)arg;
    AVFormatContext *ic = NULL;
    int err, i, ret;
    int st_index[AVMEDIA_TYPE_NB];		// 流索引
    AVPacket pkt1, *pkt = &pkt1;
    int64_t stream_start_time;
    int pkt_in_play_range = 0;
    AVDictionaryEntry *t;
    AVDictionary **opts;
    int orig_nb_streams;			// 总共有多少流成分
    SDL_mutex *wait_mutex = SDL_CreateMutex();
    int scan_all_pmts_set = 0;
    int64_t pkt_ts;

    if (!wait_mutex) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateMutex(): %s\n", SDL_GetError());
        ret = AVERROR(ENOMEM);
        goto fail;
    }


    memset(st_index, -1, sizeof(st_index));
    is->last_video_stream = is->video_stream = -1;
    is->last_audio_stream = is->audio_stream = -1;
    is->last_subtitle_stream = is->subtitle_stream = -1;
    is->eof = 0;

    ic = avformat_alloc_context();
    if (!ic) {
        av_log(NULL, AV_LOG_FATAL, "Could not allocate context.\n");
        ret = AVERROR(ENOMEM);
        goto fail;
    }
    ic->interrupt_callback.callback = decode_interrupt_cb;		// 回调
    ic->interrupt_callback.opaque = is;
    if (!av_dict_get(format_opts, "scan_all_pmts", NULL, AV_DICT_MATCH_CASE)) {
        av_dict_set(&format_opts, "scan_all_pmts", "1", AV_DICT_DONT_OVERWRITE);
        scan_all_pmts_set = 1;
    }
    err = avformat_open_input(&ic, is->filename, is->iformat, &format_opts);
    if (err < 0) {
        //print_error(is->filename, err);
        ret = -1;
        goto fail;
    }
    if (scan_all_pmts_set)
        av_dict_set(&format_opts, "scan_all_pmts", NULL, AV_DICT_MATCH_CASE);

    if ((t = av_dict_get(format_opts, "", NULL, AV_DICT_IGNORE_SUFFIX))) {
        av_log(NULL, AV_LOG_ERROR, "Option %s not found.\n", t->key);
        ret = AVERROR_OPTION_NOT_FOUND;
        goto fail;
    }
    is->ic = ic;

    if (genpts)
        ic->flags |= AVFMT_FLAG_GENPTS;

    av_format_inject_global_side_data(ic);		// ?

    opts = setup_find_stream_info_opts(ic, codec_opts);
    orig_nb_streams = ic->nb_streams;

    // 确定格式
    err = avformat_find_stream_info(ic, opts);

    for (i = 0; i < orig_nb_streams; i++)
        av_dict_free(&opts[i]);
    av_freep(&opts);

    if (err < 0) {
        av_log(NULL, AV_LOG_WARNING,
               "%s: could not find codec parameters\n", is->filename);
        ret = -1;
        goto fail;
    }

    if (ic->pb)
        ic->pb->eof_reached = 0; // FIXME hack, ffplay maybe should not use avio_feof() to test for the end

    if (seek_by_bytes < 0)
        seek_by_bytes = !!(ic->iformat->flags & AVFMT_TS_DISCONT) && strcmp("ogg", ic->iformat->name);

    is->max_frame_duration = (ic->iformat->flags & AVFMT_TS_DISCONT) ? 10.0 : 3600.0;

    if (!window_title && (t = av_dict_get(ic->metadata, "title", NULL, 0)))
        window_title = av_asprintf("%s - %s", t->value, input_filename);

    /* if seeking requested, we execute it */
    // 如果需要指定起始位置
    if (start_time != AV_NOPTS_VALUE) {
        int64_t timestamp;

        timestamp = start_time;
        /* add the stream start time */
        if (ic->start_time != AV_NOPTS_VALUE)
            timestamp += ic->start_time;
        ret = avformat_seek_file(ic, -1, INT64_MIN, timestamp, INT64_MAX, 0);
        if (ret < 0) {
            av_log(NULL, AV_LOG_WARNING, "%s: could not seek to position %0.3f\n",
                    is->filename, (double)timestamp / AV_TIME_BASE);
        }
    }

    // 是否为实时流媒体
    is->realtime = is_realtime(ic);

    // 打印码流信息
    if (show_status)
        av_dump_format(ic, 0, is->filename, 0);

    // 查找码流对应的索引
    for (i = 0; i < ic->nb_streams; i++) {
        AVStream *st = ic->streams[i];
        enum AVMediaType type = st->codecpar->codec_type;
        st->discard = AVDISCARD_ALL;
        if (type >= 0 && wanted_stream_spec[type] && st_index[type] == -1)
            if (avformat_match_stream_specifier(ic, st, wanted_stream_spec[type]) > 0)
                st_index[type] = i;
    }
    for (i = 0; i < AVMEDIA_TYPE_NB; i++) {
        if (wanted_stream_spec[i] && st_index[i] == -1) {
            av_log(NULL, AV_LOG_ERROR, "Stream specifier %s does not match any %s stream\n", wanted_stream_spec[i], av_get_media_type_string((enum AVMediaType)i));
            st_index[i] = INT_MAX;
        }
    }

    if (!video_disable)
        st_index[AVMEDIA_TYPE_VIDEO] =
            av_find_best_stream(ic, AVMEDIA_TYPE_VIDEO,
                                st_index[AVMEDIA_TYPE_VIDEO], -1, NULL, 0);
    if (!audio_disable)
        st_index[AVMEDIA_TYPE_AUDIO] =
            av_find_best_stream(ic, AVMEDIA_TYPE_AUDIO,
                                st_index[AVMEDIA_TYPE_AUDIO],
                                st_index[AVMEDIA_TYPE_VIDEO],
                                NULL, 0);
    if (!video_disable && !subtitle_disable)
        st_index[AVMEDIA_TYPE_SUBTITLE] =
            av_find_best_stream(ic, AVMEDIA_TYPE_SUBTITLE,
                                st_index[AVMEDIA_TYPE_SUBTITLE],
                                (st_index[AVMEDIA_TYPE_AUDIO] >= 0 ?
                                 st_index[AVMEDIA_TYPE_AUDIO] :
                                 st_index[AVMEDIA_TYPE_VIDEO]),
                                NULL, 0);

    is->show_mode = show_mode;
    if (st_index[AVMEDIA_TYPE_VIDEO] >= 0) {
        AVStream *st = ic->streams[st_index[AVMEDIA_TYPE_VIDEO]];
        AVCodecParameters *codecpar = st->codecpar;
        AVRational sar = av_guess_sample_aspect_ratio(ic, st, NULL);
        if (codecpar->width)
            set_default_window_size(codecpar->width, codecpar->height, sar);
    }

    /* open the streams */
    // 打开码流,主要是解码器,并初始化相关的配置
    if (st_index[AVMEDIA_TYPE_AUDIO] >= 0) {
        stream_component_open(is, st_index[AVMEDIA_TYPE_AUDIO]);
    }

    ret = -1;
    if (st_index[AVMEDIA_TYPE_VIDEO] >= 0) {
        ret = stream_component_open(is, st_index[AVMEDIA_TYPE_VIDEO]);
    }
    if (is->show_mode == SHOW_MODE_NONE)
        is->show_mode = ret >= 0 ? SHOW_MODE_VIDEO : SHOW_MODE_RDFT;

    if (st_index[AVMEDIA_TYPE_SUBTITLE] >= 0) {
        stream_component_open(is, st_index[AVMEDIA_TYPE_SUBTITLE]);
    }

    if (is->video_stream < 0 && is->audio_stream < 0) {
        av_log(NULL, AV_LOG_FATAL, "Failed to open file '%s' or configure filtergraph\n",
               is->filename);
        ret = -1;
        goto fail;
    }

    if (infinite_buffer < 0 && is->realtime)
        infinite_buffer = 1;

    for (;;) {
        if (is->abort_request)
            break;
        if (is->paused != is->last_paused) {
            is->last_paused = is->paused;
            if (is->paused)
                is->read_pause_return = av_read_pause(ic);
            else
                av_read_play(ic);
        }
#if CONFIG_RTSP_DEMUXER || CONFIG_MMSH_PROTOCOL
        if (is->paused &&
                (!strcmp(ic->iformat->name, "rtsp") ||
                 (ic->pb && !strncmp(input_filename, "mmsh:", 5)))) {
            /* wait 10 ms to avoid trying to get another packet */
            /* XXX: horrible */
            SDL_Delay(10);
            continue;
        }
#endif
        if (is->seek_req) {
            int64_t seek_target = is->seek_pos;
            int64_t seek_min    = is->seek_rel > 0 ? seek_target - is->seek_rel + 2: INT64_MIN;
            int64_t seek_max    = is->seek_rel < 0 ? seek_target - is->seek_rel - 2: INT64_MAX;
// FIXME the +-2 is due to rounding being not done in the correct direction in generation
//      of the seek_pos/seek_rel variables

            ret = avformat_seek_file(is->ic, -1, seek_min, seek_target, seek_max, is->seek_flags);
            if (ret < 0) {
                av_log(NULL, AV_LOG_ERROR,
                       "%s: error while seeking\n", is->ic->filename);
            } else {
                if (is->audio_stream >= 0) {
                    packet_queue_flush(&is->audioq);
                    packet_queue_put(&is->audioq, &flush_pkt);
                }
                if (is->subtitle_stream >= 0) {
                    packet_queue_flush(&is->subtitleq);
                    packet_queue_put(&is->subtitleq, &flush_pkt);
                }
                if (is->video_stream >= 0) {
                    packet_queue_flush(&is->videoq);
                    packet_queue_put(&is->videoq, &flush_pkt);
                }
                if (is->seek_flags & AVSEEK_FLAG_BYTE) {
                   set_clock(&is->extclk, NAN, 0);
                } else {
                   set_clock(&is->extclk, seek_target / (double)AV_TIME_BASE, 0);
                }
            }
            is->seek_req = 0;
            is->queue_attachments_req = 1;
            is->eof = 0;
            if (is->paused)
                step_to_next_frame(is);
        }
        if (is->queue_attachments_req) {
            if (is->video_st && is->video_st->disposition & AV_DISPOSITION_ATTACHED_PIC) {
                AVPacket copy;
                if ((ret = av_copy_packet(©, &is->video_st->attached_pic)) < 0)
                    goto fail;
                packet_queue_put(&is->videoq, ©);
                packet_queue_put_nullpacket(&is->videoq, is->video_stream);
            }
            is->queue_attachments_req = 0;
        }

        /* if the queue are full, no need to read more */
        if (infinite_buffer<1 &&
              (is->audioq.size + is->videoq.size + is->subtitleq.size > MAX_QUEUE_SIZE
            || (stream_has_enough_packets(is->audio_st, is->audio_stream, &is->audioq) &&
                stream_has_enough_packets(is->video_st, is->video_stream, &is->videoq) &&
                stream_has_enough_packets(is->subtitle_st, is->subtitle_stream, &is->subtitleq)))) {
            /* wait 10 ms */
            SDL_LockMutex(wait_mutex);
            SDL_CondWaitTimeout(is->continue_read_thread, wait_mutex, 10);
            SDL_UnlockMutex(wait_mutex);
            continue;
        }
        if (!is->paused &&
            (!is->audio_st || (is->auddec.finished == is->audioq.serial && frame_queue_nb_remaining(&is->sampq) == 0)) &&
            (!is->video_st || (is->viddec.finished == is->videoq.serial && frame_queue_nb_remaining(&is->pictq) == 0))) {
            if (loop != 1 && (!loop || --loop)) {
                stream_seek(is, start_time != AV_NOPTS_VALUE ? start_time : 0, 0, 0);
            } else if (autoexit) {
                ret = AVERROR_EOF;
                goto fail;
            }
        }
        ret = av_read_frame(ic, pkt);
        if (ret < 0) {
            if ((ret == AVERROR_EOF || avio_feof(ic->pb)) && !is->eof) {
                if (is->video_stream >= 0)
                    packet_queue_put_nullpacket(&is->videoq, is->video_stream);
                if (is->audio_stream >= 0)
                    packet_queue_put_nullpacket(&is->audioq, is->audio_stream);
                if (is->subtitle_stream >= 0)
                    packet_queue_put_nullpacket(&is->subtitleq, is->subtitle_stream);
                is->eof = 1;
            }
            if (ic->pb && ic->pb->error)
                break;
            SDL_LockMutex(wait_mutex);
            SDL_CondWaitTimeout(is->continue_read_thread, wait_mutex, 10);
            SDL_UnlockMutex(wait_mutex);
            continue;
        } else {
            is->eof = 0;
        }
        /* check if packet is in play range specified by user, then queue, otherwise discard */
        stream_start_time = ic->streams[pkt->stream_index]->start_time;
        pkt_ts = pkt->pts == AV_NOPTS_VALUE ? pkt->dts : pkt->pts;
        pkt_in_play_range = duration == AV_NOPTS_VALUE ||
                (pkt_ts - (stream_start_time != AV_NOPTS_VALUE ? stream_start_time : 0)) *
                av_q2d(ic->streams[pkt->stream_index]->time_base) -
                (double)(start_time != AV_NOPTS_VALUE ? start_time : 0) / 1000000
                <= ((double)duration / 1000000);
        if (pkt->stream_index == is->audio_stream && pkt_in_play_range) {
            packet_queue_put(&is->audioq, pkt);
        } else if (pkt->stream_index == is->video_stream && pkt_in_play_range
                   && !(is->video_st->disposition & AV_DISPOSITION_ATTACHED_PIC)) {
            packet_queue_put(&is->videoq, pkt);
        } else if (pkt->stream_index == is->subtitle_stream && pkt_in_play_range) {
            packet_queue_put(&is->subtitleq, pkt);
        } else {
            av_packet_unref(pkt);
        }
    }

    ret = 0;
 fail:
    if (ic && !is->ic)
        avformat_close_input(&ic);

    if (ret != 0) {
        SDL_Event event;

        event.type = FF_QUIT_EVENT;
        event.user.data1 = is;
        SDL_PushEvent(&event);
    }
    SDL_DestroyMutex(wait_mutex);
    return 0;
}

static VideoState *stream_open(const char *filename, AVInputFormat *iformat)
{
    VideoState *is;

    is = (VideoState *)av_mallocz(sizeof(VideoState));		// 分配结构体并初始化
    if (!is)
        return NULL;
    is->filename = av_strdup(filename);			// 拷贝文件名
    if (!is->filename)
        goto fail;
    is->iformat = iformat;						// 保存输入结构体
    is->ytop    = 0;
    is->xleft   = 0;

    /* start video display */
    // 初始化解码后的帧队列
    if (frame_queue_init(&is->pictq, &is->videoq, VIDEO_PICTURE_QUEUE_SIZE, 1) < 0)
        goto fail;
    if (frame_queue_init(&is->subpq, &is->subtitleq, SUBPICTURE_QUEUE_SIZE, 0) < 0)
        goto fail;
    if (frame_queue_init(&is->sampq, &is->audioq, SAMPLE_QUEUE_SIZE, 1) < 0)
        goto fail;

    // 初始化解码器前packet的队列
    if (packet_queue_init(&is->videoq) < 0 ||
        packet_queue_init(&is->audioq) < 0 ||
        packet_queue_init(&is->subtitleq) < 0)
        goto fail;

    // 创建
    if (!(is->continue_read_thread = SDL_CreateCond())) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateCond(): %s\n", SDL_GetError());
        goto fail;
    }

    // 初始化时钟
    init_clock(&is->vidclk, &is->videoq.serial);
    init_clock(&is->audclk, &is->audioq.serial);
    init_clock(&is->extclk, &is->extclk.serial);
    is->audio_clock_serial = -1;
    // 初始化音量
    if (startup_volume < 0)
        av_log(NULL, AV_LOG_WARNING, "-volume=%d < 0, setting to 0\n", startup_volume);
    if (startup_volume > 100)
        av_log(NULL, AV_LOG_WARNING, "-volume=%d > 100, setting to 100\n", startup_volume);
    startup_volume = av_clip(startup_volume, 0, 100);
    startup_volume = av_clip(SDL_MIX_MAXVOLUME * startup_volume / 100, 0, SDL_MIX_MAXVOLUME);

    is->audio_volume = startup_volume;
    is->muted = 0;
    is->av_sync_type = av_sync_type;
    //创建读线程
    is->read_tid     = SDL_CreateThread(read_thread, "read_thread", is);
    if (!is->read_tid) {
        av_log(NULL, AV_LOG_FATAL, "SDL_CreateThread(): %s\n", SDL_GetError());
fail:
        stream_close(is);
        return NULL;
    }
    return is;
}

static void stream_cycle_channel(VideoState *is, int codec_type)
{
    AVFormatContext *ic = is->ic;
    int start_index, stream_index;
    int old_index;
    AVStream *st;
    AVProgram *p = NULL;
    int nb_streams = is->ic->nb_streams;

    if (codec_type == AVMEDIA_TYPE_VIDEO) {
        start_index = is->last_video_stream;
        old_index = is->video_stream;
    } else if (codec_type == AVMEDIA_TYPE_AUDIO) {
        start_index = is->last_audio_stream;
        old_index = is->audio_stream;
    } else {
        start_index = is->last_subtitle_stream;
        old_index = is->subtitle_stream;
    }
    stream_index = start_index;

    if (codec_type != AVMEDIA_TYPE_VIDEO && is->video_stream != -1) {
        p = av_find_program_from_stream(ic, NULL, is->video_stream);
        if (p) {
            nb_streams = p->nb_stream_indexes;
            for (start_index = 0; start_index < nb_streams; start_index++)
                if (p->stream_index[start_index] == stream_index)
                    break;
            if (start_index == nb_streams)
                start_index = -1;
            stream_index = start_index;
        }
    }

    for (;;) {
        if (++stream_index >= nb_streams)
        {
            if (codec_type == AVMEDIA_TYPE_SUBTITLE)
            {
                stream_index = -1;
                is->last_subtitle_stream = -1;
                goto the_end;
            }
            if (start_index == -1)
                return;
            stream_index = 0;
        }
        if (stream_index == start_index)
            return;
        st = is->ic->streams[p ? p->stream_index[stream_index] : stream_index];
        if (st->codecpar->codec_type == codec_type) {
            /* check that parameters are OK */
            switch (codec_type) {
            case AVMEDIA_TYPE_AUDIO:
                if (st->codecpar->sample_rate != 0 &&
                    st->codecpar->channels != 0)
                    goto the_end;
                break;
            case AVMEDIA_TYPE_VIDEO:
            case AVMEDIA_TYPE_SUBTITLE:
                goto the_end;
            default:
                break;
            }
        }
    }
 the_end:
    if (p && stream_index != -1)
        stream_index = p->stream_index[stream_index];
    av_log(NULL, AV_LOG_INFO, "Switch %s stream from #%d to #%d\n",
           av_get_media_type_string((enum AVMediaType)codec_type),
           old_index,
           stream_index);

    stream_component_close(is, old_index);
    stream_component_open(is, stream_index);
}


static void toggle_full_screen(VideoState *is)
{
    is_full_screen = !is_full_screen;
    SDL_SetWindowFullscreen(window, is_full_screen ? SDL_WINDOW_FULLSCREEN_DESKTOP : 0);
}

static void toggle_audio_display(VideoState *is)
{
    int next = is->show_mode;
    do {
        next = (next + 1) % SHOW_MODE_NB;
    } while (next != is->show_mode && (next == SHOW_MODE_VIDEO && !is->video_st || next != SHOW_MODE_VIDEO && !is->audio_st));
    if (is->show_mode != (enum ShowMode)next) {
        is->force_refresh = 1;
        is->show_mode = (enum ShowMode)next;
    }
}

static void refresh_loop_wait_event(VideoState *is, SDL_Event *event) {
    double remaining_time = 0.0;
    SDL_PumpEvents();
    while (!SDL_PeepEvents(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT)) {
        if (!cursor_hidden && av_gettime_relative() - cursor_last_shown > CURSOR_HIDE_DELAY) {
            SDL_ShowCursor(0);
            cursor_hidden = 1;
        }
        if (remaining_time > 0.0)
            av_usleep((int64_t)(remaining_time * 1000000.0));
        remaining_time = REFRESH_RATE;
        if (is->show_mode != SHOW_MODE_NONE && (!is->paused || is->force_refresh))
            video_refresh(is, &remaining_time);
        SDL_PumpEvents();
    }
}

static void seek_chapter(VideoState *is, int incr)
{
    int64_t pos = get_master_clock(is) * AV_TIME_BASE;
    int i;

    if (!is->ic->nb_chapters)
        return;

    /* find the current chapter */
    for (i = 0; i < is->ic->nb_chapters; i++) {
        AVChapter *ch = is->ic->chapters[i];
        if (av_compare_ts(pos, AV_TIME_BASE_Q, ch->start, ch->time_base) < 0) {
            i--;
            break;
        }
    }

    i += incr;
    i = FFMAX(i, 0);
    if (i >= is->ic->nb_chapters)
        return;

    av_log(NULL, AV_LOG_VERBOSE, "Seeking to chapter %d.\n", i);
    stream_seek(is, av_rescale_q(is->ic->chapters[i]->start, is->ic->chapters[i]->time_base,
                                 AV_TIME_BASE_Q), 0, 0);
}

/* handle an event sent by the GUI */
static void event_loop(VideoState *cur_stream)
{
    SDL_Event event;
    double incr, pos, frac;

    for (;;) {
        double x;
        refresh_loop_wait_event(cur_stream, &event);
        switch (event.type) {
        case SDL_KEYDOWN:				// 键盘事件
            if (exit_on_keydown) {
                do_exit(cur_stream);
                break;
            }
            switch (event.key.keysym.sym) {
            case SDLK_ESCAPE:
            case SDLK_q:
                do_exit(cur_stream);
                break;
            case SDLK_f:
                toggle_full_screen(cur_stream);
                cur_stream->force_refresh = 1;
                break;
            case SDLK_p:
            case SDLK_SPACE:
                toggle_pause(cur_stream);
                break;
            case SDLK_m:
                toggle_mute(cur_stream);
                break;
            case SDLK_KP_MULTIPLY:
            case SDLK_0:
                update_volume(cur_stream, 1, SDL_VOLUME_STEP);
                break;
            case SDLK_KP_DIVIDE:
            case SDLK_9:
                update_volume(cur_stream, -1, SDL_VOLUME_STEP);
                break;
            case SDLK_s: // S: Step to next frame
                step_to_next_frame(cur_stream);
                break;
            case SDLK_a:
                stream_cycle_channel(cur_stream, AVMEDIA_TYPE_AUDIO);
                break;
            case SDLK_v:
                stream_cycle_channel(cur_stream, AVMEDIA_TYPE_VIDEO);
                break;
            case SDLK_c:
                stream_cycle_channel(cur_stream, AVMEDIA_TYPE_VIDEO);
                stream_cycle_channel(cur_stream, AVMEDIA_TYPE_AUDIO);
                stream_cycle_channel(cur_stream, AVMEDIA_TYPE_SUBTITLE);
                break;
            case SDLK_t:
                stream_cycle_channel(cur_stream, AVMEDIA_TYPE_SUBTITLE);
                break;
            case SDLK_w:
#if CONFIG_AVFILTER
                if (cur_stream->show_mode == SHOW_MODE_VIDEO && cur_stream->vfilter_idx < nb_vfilters - 1) {
                    if (++cur_stream->vfilter_idx >= nb_vfilters)
                        cur_stream->vfilter_idx = 0;
                } else {
                    cur_stream->vfilter_idx = 0;
                    toggle_audio_display(cur_stream);
                }
#else
                toggle_audio_display(cur_stream);
#endif
                break;
            case SDLK_PAGEUP:
                if (cur_stream->ic->nb_chapters <= 1) {
                    incr = 600.0;
                    goto do_seek;
                }
                seek_chapter(cur_stream, 1);
                break;
            case SDLK_PAGEDOWN:
                if (cur_stream->ic->nb_chapters <= 1) {
                    incr = -600.0;
                    goto do_seek;
                }
                seek_chapter(cur_stream, -1);
                break;
            case SDLK_LEFT:
                incr = -10.0;
                goto do_seek;
            case SDLK_RIGHT:
                incr = 10.0;
                goto do_seek;
            case SDLK_UP:
                incr = 60.0;
                goto do_seek;
            case SDLK_DOWN:
                incr = -60.0;
            do_seek:
                    if (seek_by_bytes) {
                        pos = -1;
                        if (pos < 0 && cur_stream->video_stream >= 0)
                            pos = frame_queue_last_pos(&cur_stream->pictq);
                        if (pos < 0 && cur_stream->audio_stream >= 0)
                            pos = frame_queue_last_pos(&cur_stream->sampq);
                        if (pos < 0)
                            pos = avio_tell(cur_stream->ic->pb);
                        if (cur_stream->ic->bit_rate)
                            incr *= cur_stream->ic->bit_rate / 8.0;
                        else
                            incr *= 180000.0;
                        pos += incr;
                        stream_seek(cur_stream, pos, incr, 1);
                    } else {
                        pos = get_master_clock(cur_stream);
                        if (isnan(pos))
                            pos = (double)cur_stream->seek_pos / AV_TIME_BASE;
                        pos += incr;
                        if (cur_stream->ic->start_time != AV_NOPTS_VALUE && pos < cur_stream->ic->start_time / (double)AV_TIME_BASE)
                            pos = cur_stream->ic->start_time / (double)AV_TIME_BASE;
                        stream_seek(cur_stream, (int64_t)(pos * AV_TIME_BASE), (int64_t)(incr * AV_TIME_BASE), 0);
                    }
                break;
            default:
                break;
            }
            break;
        case SDL_MOUSEBUTTONDOWN:		// 鼠标按下事件
            if (exit_on_mousedown) {
                do_exit(cur_stream);
                break;
            }
            if (event.button.button == SDL_BUTTON_LEFT) {
                static int64_t last_mouse_left_click = 0;
                if (av_gettime_relative() - last_mouse_left_click <= 500000) {
                    toggle_full_screen(cur_stream);
                    cur_stream->force_refresh = 1;
                    last_mouse_left_click = 0;
                } else {
                    last_mouse_left_click = av_gettime_relative();
                }
            }
        case SDL_MOUSEMOTION:			// 鼠标移动事件
            if (cursor_hidden) {
                SDL_ShowCursor(1);
                cursor_hidden = 0;
            }
            cursor_last_shown = av_gettime_relative();
            if (event.type == SDL_MOUSEBUTTONDOWN) {
                if (event.button.button != SDL_BUTTON_RIGHT)
                    break;
                x = event.button.x;
            } else {
                if (!(event.motion.state & SDL_BUTTON_RMASK))
                    break;
                x = event.motion.x;
            }
                if (seek_by_bytes || cur_stream->ic->duration <= 0) {
                    uint64_t size =  avio_size(cur_stream->ic->pb);
                    stream_seek(cur_stream, size*x/cur_stream->width, 0, 1);
                } else {
                    int64_t ts;
                    int ns, hh, mm, ss;
                    int tns, thh, tmm, tss;
                    tns  = cur_stream->ic->duration / 1000000LL;
                    thh  = tns / 3600;
                    tmm  = (tns % 3600) / 60;
                    tss  = (tns % 60);
                    frac = x / cur_stream->width;
                    ns   = frac * tns;
                    hh   = ns / 3600;
                    mm   = (ns % 3600) / 60;
                    ss   = (ns % 60);
                    av_log(NULL, AV_LOG_INFO,
                           "Seek to %2.0f%% (%2d:%02d:%02d) of total duration (%2d:%02d:%02d)       \n", frac*100,
                            hh, mm, ss, thh, tmm, tss);
                    ts = frac * cur_stream->ic->duration;
                    if (cur_stream->ic->start_time != AV_NOPTS_VALUE)
                        ts += cur_stream->ic->start_time;
                    stream_seek(cur_stream, ts, 0, 0);
                }
            break;
        case SDL_WINDOWEVENT:		// 窗口事件
            switch (event.window.event) {
                case SDL_WINDOWEVENT_RESIZED:
                    screen_width  = cur_stream->width  = event.window.data1;
                    screen_height = cur_stream->height = event.window.data2;
                    if (cur_stream->vis_texture) {
                        SDL_DestroyTexture(cur_stream->vis_texture);
                        cur_stream->vis_texture = NULL;
                    }
                case SDL_WINDOWEVENT_EXPOSED:
                    cur_stream->force_refresh = 1;
            }
            break;
        case SDL_QUIT:
        case FF_QUIT_EVENT:		// ffplay自定义事件
            do_exit(cur_stream);
            break;
        default:
            break;
        }
    }
}

//static int opt_frame_size(void *optctx, const char *opt, const char *arg)
//{
//    av_log(NULL, AV_LOG_WARNING, "Option -s is deprecated, use -video_size.\n");
//    return opt_default(NULL, "video_size", arg);
//}

//static int opt_width(void *optctx, const char *opt, const char *arg)
//{
//    screen_width = parse_number_or_die(opt, arg, OPT_INT64, 1, INT_MAX);
//    return 0;
//}

//static int opt_height(void *optctx, const char *opt, const char *arg)
//{
//    screen_height = parse_number_or_die(opt, arg, OPT_INT64, 1, INT_MAX);
//    return 0;
//}

//static int opt_format(void *optctx, const char *opt, const char *arg)
//{
//    file_iformat = av_find_input_format(arg);
//    if (!file_iformat) {
//        av_log(NULL, AV_LOG_FATAL, "Unknown input format: %s\n", arg);
//        return AVERROR(EINVAL);
//    }
//    return 0;
//}

//static int opt_frame_pix_fmt(void *optctx, const char *opt, const char *arg)
//{
//    av_log(NULL, AV_LOG_WARNING, "Option -pix_fmt is deprecated, use -pixel_format.\n");
//    return opt_default(NULL, "pixel_format", arg);
//}

//static int opt_sync(void *optctx, const char *opt, const char *arg)
//{
//    if (!strcmp(arg, "audio"))
//        av_sync_type = AV_SYNC_AUDIO_MASTER;
//    else if (!strcmp(arg, "video"))
//        av_sync_type = AV_SYNC_VIDEO_MASTER;
//    else if (!strcmp(arg, "ext"))
//        av_sync_type = AV_SYNC_EXTERNAL_CLOCK;
//    else {
//        av_log(NULL, AV_LOG_ERROR, "Unknown value for %s: %s\n", opt, arg);
//        exit(1);
//    }
//    return 0;
//}

//static int opt_seek(void *optctx, const char *opt, const char *arg)
//{
//    start_time = parse_time_or_die(opt, arg, 1);
//    return 0;
//}

//static int opt_duration(void *optctx, const char *opt, const char *arg)
//{
//    duration = parse_time_or_die(opt, arg, 1);
//    return 0;
//}

//static int opt_show_mode(void *optctx, const char *opt, const char *arg)
//{
//    show_mode = (enum ShowMode)(!strcmp(arg, "video") ? SHOW_MODE_VIDEO :
//                !strcmp(arg, "waves") ? SHOW_MODE_WAVES :
//                !strcmp(arg, "rdft" ) ? SHOW_MODE_RDFT  :
//                parse_number_or_die(opt, arg, OPT_INT, 0, SHOW_MODE_NB-1));
//    return 0;
//}

//static void opt_input_file(void *optctx, const char *filename)
//{
//    if (input_filename) {
//        av_log(NULL, AV_LOG_FATAL,
//               "Argument '%s' provided as input filename, but '%s' was already specified.\n",
//                filename, input_filename);
//        exit(1);
//    }
//    if (!strcmp(filename, "-"))
//        filename = "pipe:";
//    input_filename = filename;
//}

//static int opt_codec(void *optctx, const char *opt, const char *arg)
//{
//   const char *spec = strchr(opt, ':');
//   if (!spec) {
//       av_log(NULL, AV_LOG_ERROR,
//              "No media specifier was specified in '%s' in option '%s'\n",
//               arg, opt);
//       return AVERROR(EINVAL);
//   }
//   spec++;
//   switch (spec[0]) {
//   case 'a' :    audio_codec_name = arg; break;
//   case 's' : subtitle_codec_name = arg; break;
//   case 'v' :    video_codec_name = arg; break;
//   default:
//       av_log(NULL, AV_LOG_ERROR,
//              "Invalid media specifier '%s' in option '%s'\n", spec, opt);
//       return AVERROR(EINVAL);
//   }
//   return 0;
//}

static int dummy;



static void show_usage(void)
{
    av_log(NULL, AV_LOG_INFO, "Simple media player\n");
    av_log(NULL, AV_LOG_INFO, "usage: %s [options] input_file\n", program_name);
    av_log(NULL, AV_LOG_INFO, "\n");
}



static int lockmgr(void **mtx, enum AVLockOp op)
{
   switch(op) {
      case AV_LOCK_CREATE:
          *mtx = SDL_CreateMutex();
          if(!*mtx) {
              av_log(NULL, AV_LOG_FATAL, "SDL_CreateMutex(): %s\n", SDL_GetError());
              return 1;
          }
          return 0;
      case AV_LOCK_OBTAIN:
          return !!SDL_LockMutex((SDL_mutex *)*mtx);
      case AV_LOCK_RELEASE:
          return !!SDL_UnlockMutex((SDL_mutex *)*mtx);
      case AV_LOCK_DESTROY:
          SDL_DestroyMutex((SDL_mutex *)*mtx);
          return 0;
   }
   return 1;
}
#undef main
/* Called from the main */
int main(int argc, char **argv)
{
    int flags;
    VideoState *is;


    av_log_set_flags(AV_LOG_SKIP_REPEATED);


    av_register_all();
    avformat_network_init();


    signal(SIGINT , sigterm_handler); /* Interrupt (ANSI).    */
    signal(SIGTERM, sigterm_handler); /* Termination (ANSI).  */

    char fileName[256] = {"source.200kbps.768x320.flv"};

    input_filename = fileName;
    // 必须有输入名
    if (!input_filename) {
        show_usage();
        av_log(NULL, AV_LOG_FATAL, "An input file must be specified\n");
        av_log(NULL, AV_LOG_FATAL,
               "Use -h to get full help or, even better, run 'man %s'\n", program_name);
        exit(1);
    }

    // 是否显示视频
    if (display_disable) {
        video_disable = 1;
    }
    flags = SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER;
    // 是否运行音频
    if (audio_disable)
        flags &= ~SDL_INIT_AUDIO;
    else {
        /* Try to work around an occasional ALSA buffer underflow issue when the
         * period size is NPOT due to ALSA resampling by forcing the buffer size. */
        if (!SDL_getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE"))
            SDL_setenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE","1", 1);
    }
    if (display_disable)
        flags &= ~SDL_INIT_VIDEO;
//    if (SDL_Init (flags)) {
//        av_log(NULL, AV_LOG_FATAL, "Could not initialize SDL - %s\n", SDL_GetError());
//        av_log(NULL, AV_LOG_FATAL, "(Did you set the DISPLAY variable?)\n");
//        exit(1);
//    }


    SDL_EventState(SDL_SYSWMEVENT, SDL_IGNORE);		// System specific event
    SDL_EventState(SDL_USEREVENT, SDL_IGNORE);

    if (av_lockmgr_register(lockmgr)) {
        av_log(NULL, AV_LOG_FATAL, "Could not initialize lock manager!\n");
        do_exit(NULL);
    }

    av_init_packet(&flush_pkt);					// 初始化
    flush_pkt.data = (uint8_t *)&flush_pkt;

    is = stream_open(input_filename, file_iformat);			// 打开码流并初始化
    if (!is) {
        av_log(NULL, AV_LOG_FATAL, "Failed to initialize VideoState!\n");
        do_exit(NULL);
    }

    // 事件响应
    event_loop(is);

    /* never returns */

    return 0;
}

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