FFmpeg的av_read_frame()的分析
分析av_read_frame()
—libavformat\utils.c
1,av_read_frame()调用了read_frame_internal()函数
//获取一个AVPacket
/*
* av_read_frame - 新版本的ffmpeg用的是av_read_frame，而老版本的是av_read_packet
* 。区别是av_read_packet读出的是包，它可能是半帧或多帧，不保证帧的完整性。av_read_frame对
* av_read_packet进行了封装，使读出的数据总是完整的帧
*/
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
{
const int genpts = s->flags & AVFMT_FLAG_GENPTS;
int eof = 0;
int ret;
AVStream *st;
if (!genpts) {
/**
* This buffer is only needed when packets were already buffered but
* not decoded, for example to get the codec parameters in MPEG
* streams.
* 一般情况下会调用read_frame_internal(s, pkt)
* 直接返回
*/
ret = s->internal->packet_buffer
? read_from_packet_buffer(&s->internal->packet_buffer,
&s->internal->packet_buffer_end, pkt)
: read_frame_internal(s, pkt);
if (ret < 0)
return ret;
goto return_packet;
}
for (;;) {
AVPacketList *pktl = s->internal->packet_buffer;
if (pktl) {
AVPacket *next_pkt = &pktl->pkt;
if (next_pkt->dts != AV_NOPTS_VALUE) {
int wrap_bits = s->streams[next_pkt->stream_index]->pts_wrap_bits;
// last dts seen for this stream. if any of packets following
// current one had no dts, we will set this to AV_NOPTS_VALUE.
int64_t last_dts = next_pkt->dts;
while (pktl && next_pkt->pts == AV_NOPTS_VALUE) {
if (pktl->pkt.stream_index == next_pkt->stream_index &&
(av_compare_mod(next_pkt->dts, pktl->pkt.dts, 2LL << (wrap_bits - 1)) < 0)) {
if (av_compare_mod(pktl->pkt.pts, pktl->pkt.dts, 2LL << (wrap_bits - 1))) {
// not B-frame
next_pkt->pts = pktl->pkt.dts;
}
if (last_dts != AV_NOPTS_VALUE) {
// Once last dts was set to AV_NOPTS_VALUE, we don't change it.
last_dts = pktl->pkt.dts;
}
}
pktl = pktl->next;
}
if (eof && next_pkt->pts == AV_NOPTS_VALUE && last_dts != AV_NOPTS_VALUE) {
// Fixing the last reference frame had none pts issue (For MXF etc).
// We only do this when
// 1. eof.
// 2. we are not able to resolve a pts value for current packet.
// 3. the packets for this stream at the end of the files had valid dts.
next_pkt->pts = last_dts + next_pkt->duration;
}
pktl = s->internal->packet_buffer;
}
/* read packet from packet buffer, if there is data */
st = s->streams[next_pkt->stream_index];
if (!(next_pkt->pts == AV_NOPTS_VALUE && st->discard < AVDISCARD_ALL &&
next_pkt->dts != AV_NOPTS_VALUE && !eof)) {
ret = read_from_packet_buffer(&s->internal->packet_buffer,
&s->internal->packet_buffer_end, pkt);
goto return_packet;
}
}
ret = read_frame_internal(s, pkt);
if (ret < 0) {
if (pktl && ret != AVERROR(EAGAIN)) {
eof = 1;
continue;
} else
return ret;
}
ret = add_to_pktbuf(&s->internal->packet_buffer, pkt,
&s->internal->packet_buffer_end, 1);
av_packet_unref(pkt);
if (ret < 0)
return ret;
}
return_packet:
st = s->streams[pkt->stream_index];
if ((s->iformat->flags & AVFMT_GENERIC_INDEX) && pkt->flags & AV_PKT_FLAG_KEY) {
ff_reduce_index(s, st->index);
av_add_index_entry(st, pkt->pos, pkt->dts, 0, 0, AVINDEX_KEYFRAME);
}
if (is_relative(pkt->dts))
pkt->dts -= RELATIVE_TS_BASE;
if (is_relative(pkt->pts))
pkt->pts -= RELATIVE_TS_BASE;
return ret;
}2,调用ff_read_packet()函数从相应AVInputFormat读取数据和parse_packet()函数
ret = s->iformat->read_packet(s, pkt);
int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret, i, err;
AVStream *st;
for (;;) {
AVPacketList *pktl = s->internal->raw_packet_buffer;
if (pktl) {
*pkt = pktl->pkt;
st = s->streams[pkt->stream_index];
if (s->internal->raw_packet_buffer_remaining_size <= 0)
if ((err = probe_codec(s, st, NULL)) < 0)
return err;
if (st->request_probe <= 0) {
s->internal->raw_packet_buffer = pktl->next;
s->internal->raw_packet_buffer_remaining_size += pkt->size;
av_free(pktl);
return 0;
}
}
pkt->data = NULL;
pkt->size = 0;
av_init_packet(pkt);
//关键：读取Packet
ret = s->iformat->read_packet(s, pkt);
if (ret < 0) {
/* Some demuxers return FFERROR_REDO when they consume
data and discard it (ignored streams, junk, extradata).
We must re-call the demuxer to get the real packet. */
if (ret == FFERROR_REDO)
continue;
if (!pktl || ret == AVERROR(EAGAIN))
return ret;
for (i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (st->probe_packets || st->request_probe > 0)
if ((err = probe_codec(s, st, NULL)) < 0)
return err;
av_assert0(st->request_probe <= 0);
}
continue;
}
if (!pkt->buf) {
AVPacket tmp = { 0 };
ret = av_packet_ref(&tmp, pkt);
if (ret < 0)
return ret;
*pkt = tmp;
}
if ((s->flags & AVFMT_FLAG_DISCARD_CORRUPT) &&
(pkt->flags & AV_PKT_FLAG_CORRUPT)) {
av_log(s, AV_LOG_WARNING,
"Dropped corrupted packet (stream = %d)\n",
pkt->stream_index);
av_packet_unref(pkt);
continue;
}
if (pkt->stream_index >= (unsigned)s->nb_streams) {
av_log(s, AV_LOG_ERROR, "Invalid stream index %d\n", pkt->stream_index);
continue;
}
st = s->streams[pkt->stream_index];
if (update_wrap_reference(s, st, pkt->stream_index, pkt) && st->pts_wrap_behavior == AV_PTS_WRAP_SUB_OFFSET) {
// correct first time stamps to negative values
if (!is_relative(st->first_dts))
st->first_dts = wrap_timestamp(st, st->first_dts);
if (!is_relative(st->start_time))
st->start_time = wrap_timestamp(st, st->start_time);
if (!is_relative(st->cur_dts))
st->cur_dts = wrap_timestamp(st, st->cur_dts);
}
pkt->dts = wrap_timestamp(st, pkt->dts);
pkt->pts = wrap_timestamp(st, pkt->pts);
force_codec_ids(s, st);
/* TODO: audio: time filter; video: frame reordering (pts != dts) */
if (s->use_wallclock_as_timestamps)
pkt->dts = pkt->pts = av_rescale_q(av_gettime(), AV_TIME_BASE_Q, st->time_base);
if (!pktl && st->request_probe <= 0)
return ret;
err = add_to_pktbuf(&s->internal->raw_packet_buffer, pkt,
&s->internal->raw_packet_buffer_end, 0);
if (err)
return err;
s->internal->raw_packet_buffer_remaining_size -= pkt->size;
if ((err = probe_codec(s, st, pkt)) < 0)
return err;
}
}
3,ff_read_packet()中最关键的地方就是调用了AVInputFormat的read_packet()方法。
AVInputFormat的read_packet()是一个函数指针，指向当前的AVInputFormat的读取数据的函数
flv的封装格式 —libavformat\flvdec.c
4,parse_packet(AVFormatContext *s, AVPacket *pkt, int stream_index) 函数
AVInputFormat ff_flv_demuxer = {
.name = "flv",
.long_name = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"),
.priv_data_size = sizeof(FLVContext),
.read_probe = flv_probe,
.read_header = flv_read_header,
.read_packet = flv_read_packet,
.read_seek = flv_read_seek,
.read_close = flv_read_close,
.extensions = "flv",
.priv_class = &flv_class,
};
read_packet()对应是flv_read_packet()函数
中间要了解flv的格式
--flv_read_packet()函数 ---libavformat\flvdec.c 最终调用了相应AVCodecParser的av_parser_parse2()函数，解析出来AVPacket。此后根据解析的信息还进行了一系列的赋值工作
/*
* FLV demuxer
* Copyright (c) 2003 The FFmpeg Project
*
* This demuxer will generate a 1 byte extradata for VP6F content.
* It is composed of:
* - upper 4 bits: difference between encoded width and visible width
* - lower 4 bits: difference between encoded height and visible height
*
* 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
*/
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/dict.h"
#include "libavutil/opt.h"
#include "libavutil/intfloat.h"
#include "libavutil/mathematics.h"
#include "libavcodec/bytestream.h"
#include "libavcodec/mpeg4audio.h"
#include "avformat.h"
#include "internal.h"
#include "avio_internal.h"
#include "flv.h"
#define VALIDATE_INDEX_TS_THRESH 2500
#define RESYNC_BUFFER_SIZE (1<<20)
typedef struct FLVContext {
const AVClass *class; ///< Class for private options.
int trust_metadata; ///< configure streams according onMetaData
int wrong_dts; ///< wrong dts due to negative cts
uint8_t *new_extradata[FLV_STREAM_TYPE_NB];
int new_extradata_size[FLV_STREAM_TYPE_NB];
int last_sample_rate;
int last_channels;
struct {
int64_t dts;
int64_t pos;
} validate_index[2];
int validate_next;
int validate_count;
int searched_for_end;
uint8_t resync_buffer[2*RESYNC_BUFFER_SIZE];
int broken_sizes;
int sum_flv_tag_size;
int last_keyframe_stream_index;
int keyframe_count;
int64_t video_bit_rate;
int64_t audio_bit_rate;
int64_t *keyframe_times;
int64_t *keyframe_filepositions;
int missing_streams;
AVRational framerate;
} FLVContext;
static int probe(AVProbeData *p, int live)
{
const uint8_t *d = p->buf;
unsigned offset = AV_RB32(d + 5);
if (d[0] == 'F' &&
d[1] == 'L' &&
d[2] == 'V' &&
d[3] < 5 && d[5] == 0 &&
offset + 100 < p->buf_size &&
offset > 8) {
int is_live = !memcmp(d + offset + 40, "NGINX RTMP", 10);
if (live == is_live)
return AVPROBE_SCORE_MAX;
}
return 0;
}
static int flv_probe(AVProbeData *p)
{
return probe(p, 0);
}
static int live_flv_probe(AVProbeData *p)
{
return probe(p, 1);
}
static void add_keyframes_index(AVFormatContext *s)
{
FLVContext *flv = s->priv_data;
AVStream *stream = NULL;
unsigned int i = 0;
if (flv->last_keyframe_stream_index < 0) {
av_log(s, AV_LOG_DEBUG, "keyframe stream hasn't been created\n");
return;
}
av_assert0(flv->last_keyframe_stream_index <= s->nb_streams);
stream = s->streams[flv->last_keyframe_stream_index];
if (stream->nb_index_entries == 0) {
for (i = 0; i < flv->keyframe_count; i++) {
av_log(s, AV_LOG_TRACE, "keyframe filepositions = %"PRId64" times = %"PRId64"\n",
flv->keyframe_filepositions[i], flv->keyframe_times[i] * 1000);
av_add_index_entry(stream, flv->keyframe_filepositions[i],
flv->keyframe_times[i] * 1000, 0, 0, AVINDEX_KEYFRAME);
}
} else
av_log(s, AV_LOG_WARNING, "Skipping duplicate index\n");
if (stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
av_freep(&flv->keyframe_times);
av_freep(&flv->keyframe_filepositions);
flv->keyframe_count = 0;
}
}
static AVStream *create_stream(AVFormatContext *s, int codec_type)
{
FLVContext *flv = s->priv_data;
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return NULL;
st->codecpar->codec_type = codec_type;
if (s->nb_streams>=3 ||( s->nb_streams==2
&& s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE
&& s->streams[1]->codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE))
s->ctx_flags &= ~AVFMTCTX_NOHEADER;
if (codec_type == AVMEDIA_TYPE_AUDIO) {
st->codecpar->bit_rate = flv->audio_bit_rate;
flv->missing_streams &= ~FLV_HEADER_FLAG_HASAUDIO;
}
if (codec_type == AVMEDIA_TYPE_VIDEO) {
st->codecpar->bit_rate = flv->video_bit_rate;
flv->missing_streams &= ~FLV_HEADER_FLAG_HASVIDEO;
st->avg_frame_rate = flv->framerate;
}
avpriv_set_pts_info(st, 32, 1, 1000); /* 32 bit pts in ms */
flv->last_keyframe_stream_index = s->nb_streams - 1;
add_keyframes_index(s);
return st;
}
static int flv_same_audio_codec(AVCodecParameters *apar, int flags)
{
int bits_per_coded_sample = (flags & FLV_AUDIO_SAMPLESIZE_MASK) ? 16 : 8;
int flv_codecid = flags & FLV_AUDIO_CODECID_MASK;
int codec_id;
if (!apar->codec_id && !apar->codec_tag)
return 1;
if (apar->bits_per_coded_sample != bits_per_coded_sample)
return 0;
switch (flv_codecid) {
// no distinction between S16 and S8 PCM codec flags
case FLV_CODECID_PCM:
codec_id = bits_per_coded_sample == 8
? AV_CODEC_ID_PCM_U8
#if HAVE_BIGENDIAN
: AV_CODEC_ID_PCM_S16BE;
#else
: AV_CODEC_ID_PCM_S16LE;
#endif
return codec_id == apar->codec_id;
case FLV_CODECID_PCM_LE:
codec_id = bits_per_coded_sample == 8
? AV_CODEC_ID_PCM_U8
: AV_CODEC_ID_PCM_S16LE;
return codec_id == apar->codec_id;
case FLV_CODECID_AAC:
return apar->codec_id == AV_CODEC_ID_AAC;
case FLV_CODECID_ADPCM:
return apar->codec_id == AV_CODEC_ID_ADPCM_SWF;
case FLV_CODECID_SPEEX:
return apar->codec_id == AV_CODEC_ID_SPEEX;
case FLV_CODECID_MP3:
return apar->codec_id == AV_CODEC_ID_MP3;
case FLV_CODECID_NELLYMOSER_8KHZ_MONO:
case FLV_CODECID_NELLYMOSER_16KHZ_MONO:
case FLV_CODECID_NELLYMOSER:
return apar->codec_id == AV_CODEC_ID_NELLYMOSER;
case FLV_CODECID_PCM_MULAW:
return apar->sample_rate == 8000 &&
apar->codec_id == AV_CODEC_ID_PCM_MULAW;
case FLV_CODECID_PCM_ALAW:
return apar->sample_rate == 8000 &&
apar->codec_id == AV_CODEC_ID_PCM_ALAW;
default:
return apar->codec_tag == (flv_codecid >> FLV_AUDIO_CODECID_OFFSET);
}
}
static void flv_set_audio_codec(AVFormatContext *s, AVStream *astream,
AVCodecParameters *apar, int flv_codecid)
{
switch (flv_codecid) {
// no distinction between S16 and S8 PCM codec flags
case FLV_CODECID_PCM:
apar->codec_id = apar->bits_per_coded_sample == 8
? AV_CODEC_ID_PCM_U8
#if HAVE_BIGENDIAN
: AV_CODEC_ID_PCM_S16BE;
#else
: AV_CODEC_ID_PCM_S16LE;
#endif
break;
case FLV_CODECID_PCM_LE:
apar->codec_id = apar->bits_per_coded_sample == 8
? AV_CODEC_ID_PCM_U8
: AV_CODEC_ID_PCM_S16LE;
break;
case FLV_CODECID_AAC:
apar->codec_id = AV_CODEC_ID_AAC;
break;
case FLV_CODECID_ADPCM:
apar->codec_id = AV_CODEC_ID_ADPCM_SWF;
break;
case FLV_CODECID_SPEEX:
apar->codec_id = AV_CODEC_ID_SPEEX;
apar->sample_rate = 16000;
break;
case FLV_CODECID_MP3:
apar->codec_id = AV_CODEC_ID_MP3;
astream->need_parsing = AVSTREAM_PARSE_FULL;
break;
case FLV_CODECID_NELLYMOSER_8KHZ_MONO:
// in case metadata does not otherwise declare samplerate
apar->sample_rate = 8000;
apar->codec_id = AV_CODEC_ID_NELLYMOSER;
break;
case FLV_CODECID_NELLYMOSER_16KHZ_MONO:
apar->sample_rate = 16000;
apar->codec_id = AV_CODEC_ID_NELLYMOSER;
break;
case FLV_CODECID_NELLYMOSER:
apar->codec_id = AV_CODEC_ID_NELLYMOSER;
break;
case FLV_CODECID_PCM_MULAW:
apar->sample_rate = 8000;
apar->codec_id = AV_CODEC_ID_PCM_MULAW;
break;
case FLV_CODECID_PCM_ALAW:
apar->sample_rate = 8000;
apar->codec_id = AV_CODEC_ID_PCM_ALAW;
break;
default:
avpriv_request_sample(s, "Audio codec (%x)",
flv_codecid >> FLV_AUDIO_CODECID_OFFSET);
apar->codec_tag = flv_codecid >> FLV_AUDIO_CODECID_OFFSET;
}
}
static int flv_same_video_codec(AVCodecParameters *vpar, int flags)
{
int flv_codecid = flags & FLV_VIDEO_CODECID_MASK;
if (!vpar->codec_id && !vpar->codec_tag)
return 1;
switch (flv_codecid) {
case FLV_CODECID_H263:
return vpar->codec_id == AV_CODEC_ID_FLV1;
case FLV_CODECID_SCREEN:
return vpar->codec_id == AV_CODEC_ID_FLASHSV;
case FLV_CODECID_SCREEN2:
return vpar->codec_id == AV_CODEC_ID_FLASHSV2;
case FLV_CODECID_VP6:
return vpar->codec_id == AV_CODEC_ID_VP6F;
case FLV_CODECID_VP6A:
return vpar->codec_id == AV_CODEC_ID_VP6A;
case FLV_CODECID_H264:
return vpar->codec_id == AV_CODEC_ID_H264;
default:
return vpar->codec_tag == flv_codecid;
}
}
static int flv_set_video_codec(AVFormatContext *s, AVStream *vstream,
int flv_codecid, int read)
{
int ret = 0;
AVCodecParameters *par = vstream->codecpar;
enum AVCodecID old_codec_id = vstream->codecpar->codec_id;
switch (flv_codecid) {
case FLV_CODECID_H263:
par->codec_id = AV_CODEC_ID_FLV1;
break;
case FLV_CODECID_REALH263:
par->codec_id = AV_CODEC_ID_H263;
break; // Really mean it this time
case FLV_CODECID_SCREEN:
par->codec_id = AV_CODEC_ID_FLASHSV;
break;
case FLV_CODECID_SCREEN2:
par->codec_id = AV_CODEC_ID_FLASHSV2;
break;
case FLV_CODECID_VP6:
par->codec_id = AV_CODEC_ID_VP6F;
case FLV_CODECID_VP6A:
if (flv_codecid == FLV_CODECID_VP6A)
par->codec_id = AV_CODEC_ID_VP6A;
if (read) {
if (par->extradata_size != 1) {
ff_alloc_extradata(par, 1);
}
if (par->extradata)
par->extradata[0] = avio_r8(s->pb);
else
avio_skip(s->pb, 1);
}
ret = 1; // 1 byte body size adjustment for flv_read_packet()
break;
case FLV_CODECID_H264:
par->codec_id = AV_CODEC_ID_H264;
vstream->need_parsing = AVSTREAM_PARSE_HEADERS;
ret = 3; // not 4, reading packet type will consume one byte
break;
case FLV_CODECID_MPEG4:
par->codec_id = AV_CODEC_ID_MPEG4;
ret = 3;
break;
default:
avpriv_request_sample(s, "Video codec (%x)", flv_codecid);
par->codec_tag = flv_codecid;
}
if (!vstream->internal->need_context_update && par->codec_id != old_codec_id) {
avpriv_request_sample(s, "Changing the codec id midstream");
return AVERROR_PATCHWELCOME;
}
return ret;
}
static int amf_get_string(AVIOContext *ioc, char *buffer, int buffsize)
{
int length = avio_rb16(ioc);
if (length >= buffsize) {
avio_skip(ioc, length);
return -1;
}
avio_read(ioc, buffer, length);
buffer[length] = '\0';
return length;
}
static int parse_keyframes_index(AVFormatContext *s, AVIOContext *ioc, int64_t max_pos)
{
FLVContext *flv = s->priv_data;
unsigned int timeslen = 0, fileposlen = 0, i;
char str_val[256];
int64_t *times = NULL;
int64_t *filepositions = NULL;
int ret = AVERROR(ENOSYS);
int64_t initial_pos = avio_tell(ioc);
if (flv->keyframe_count > 0) {
av_log(s, AV_LOG_DEBUG, "keyframes have been paresed\n");
return 0;
}
av_assert0(!flv->keyframe_times);
av_assert0(!flv->keyframe_filepositions);
if (s->flags & AVFMT_FLAG_IGNIDX)
return 0;
while (avio_tell(ioc) < max_pos - 2 &&
amf_get_string(ioc, str_val, sizeof(str_val)) > 0) {
int64_t **current_array;
unsigned int arraylen;
// Expect array object in context
if (avio_r8(ioc) != AMF_DATA_TYPE_ARRAY)
break;
arraylen = avio_rb32(ioc);
if (arraylen>>28)
break;
if (!strcmp(KEYFRAMES_TIMESTAMP_TAG , str_val) && !times) {
current_array = ×
timeslen = arraylen;
} else if (!strcmp(KEYFRAMES_BYTEOFFSET_TAG, str_val) &&
!filepositions) {
current_array = &filepositions;
fileposlen = arraylen;
} else
// unexpected metatag inside keyframes, will not use such
// metadata for indexing
break;
if (!(*current_array = av_mallocz(sizeof(**current_array) * arraylen))) {
ret = AVERROR(ENOMEM);
goto finish;
}
for (i = 0; i < arraylen && avio_tell(ioc) < max_pos - 1; i++) {
if (avio_r8(ioc) != AMF_DATA_TYPE_NUMBER)
goto invalid;
current_array[0][i] = av_int2double(avio_rb64(ioc));
}
if (times && filepositions) {
// All done, exiting at a position allowing amf_parse_object
// to finish parsing the object
ret = 0;
break;
}
}
if (timeslen == fileposlen && fileposlen>1 && max_pos <= filepositions[0]) {
for (i = 0; i < FFMIN(2,fileposlen); i++) {
flv->validate_index[i].pos = filepositions[i];
flv->validate_index[i].dts = times[i] * 1000;
flv->validate_count = i + 1;
}
flv->keyframe_times = times;
flv->keyframe_filepositions = filepositions;
flv->keyframe_count = timeslen;
times = NULL;
filepositions = NULL;
} else {
invalid:
av_log(s, AV_LOG_WARNING, "Invalid keyframes object, skipping.\n");
}
finish:
av_freep(×);
av_freep(&filepositions);
avio_seek(ioc, initial_pos, SEEK_SET);
return ret;
}
static int amf_parse_object(AVFormatContext *s, AVStream *astream,
AVStream *vstream, const char *key,
int64_t max_pos, int depth)
{
AVCodecParameters *apar, *vpar;
FLVContext *flv = s->priv_data;
AVIOContext *ioc;
AMFDataType amf_type;
char str_val[1024];
double num_val;
num_val = 0;
ioc = s->pb;
amf_type = avio_r8(ioc);
switch (amf_type) {
case AMF_DATA_TYPE_NUMBER:
num_val = av_int2double(avio_rb64(ioc));
break;
case AMF_DATA_TYPE_BOOL:
num_val = avio_r8(ioc);
break;
case AMF_DATA_TYPE_STRING:
if (amf_get_string(ioc, str_val, sizeof(str_val)) < 0) {
av_log(s, AV_LOG_ERROR, "AMF_DATA_TYPE_STRING parsing failed\n");
return -1;
}
break;
case AMF_DATA_TYPE_OBJECT:
if (key &&
(ioc->seekable & AVIO_SEEKABLE_NORMAL) &&
!strcmp(KEYFRAMES_TAG, key) && depth == 1)
if (parse_keyframes_index(s, ioc,
max_pos) < 0)
av_log(s, AV_LOG_ERROR, "Keyframe index parsing failed\n");
else
add_keyframes_index(s);
while (avio_tell(ioc) < max_pos - 2 &&
amf_get_string(ioc, str_val, sizeof(str_val)) > 0)
if (amf_parse_object(s, astream, vstream, str_val, max_pos,
depth + 1) < 0)
return -1; // if we couldn't skip, bomb out.
if (avio_r8(ioc) != AMF_END_OF_OBJECT) {
av_log(s, AV_LOG_ERROR, "Missing AMF_END_OF_OBJECT in AMF_DATA_TYPE_OBJECT\n");
return -1;
}
break;
case AMF_DATA_TYPE_NULL:
case AMF_DATA_TYPE_UNDEFINED:
case AMF_DATA_TYPE_UNSUPPORTED:
break; // these take up no additional space
case AMF_DATA_TYPE_MIXEDARRAY:
{
unsigned v;
avio_skip(ioc, 4); // skip 32-bit max array index
while (avio_tell(ioc) < max_pos - 2 &&
amf_get_string(ioc, str_val, sizeof(str_val)) > 0)
// this is the only case in which we would want a nested
// parse to not skip over the object
if (amf_parse_object(s, astream, vstream, str_val, max_pos,
depth + 1) < 0)
return -1;
v = avio_r8(ioc);
if (v != AMF_END_OF_OBJECT) {
av_log(s, AV_LOG_ERROR, "Missing AMF_END_OF_OBJECT in AMF_DATA_TYPE_MIXEDARRAY, found %d\n", v);
return -1;
}
break;
}
case AMF_DATA_TYPE_ARRAY:
{
unsigned int arraylen, i;
arraylen = avio_rb32(ioc);
for (i = 0; i < arraylen && avio_tell(ioc) < max_pos - 1; i++)
if (amf_parse_object(s, NULL, NULL, NULL, max_pos,
depth + 1) < 0)
return -1; // if we couldn't skip, bomb out.
}
break;
case AMF_DATA_TYPE_DATE:
avio_skip(ioc, 8 + 2); // timestamp (double) and UTC offset (int16)
break;
default: // unsupported type, we couldn't skip
av_log(s, AV_LOG_ERROR, "unsupported amf type %d\n", amf_type);
return -1;
}
if (key) {
apar = astream ? astream->codecpar : NULL;
vpar = vstream ? vstream->codecpar : NULL;
// stream info doesn't live any deeper than the first object
if (depth == 1) {
if (amf_type == AMF_DATA_TYPE_NUMBER ||
amf_type == AMF_DATA_TYPE_BOOL) {
if (!strcmp(key, "duration"))
s->duration = num_val * AV_TIME_BASE;
else if (!strcmp(key, "videodatarate") &&
0 <= (int)(num_val * 1024.0))
flv->video_bit_rate = num_val * 1024.0;
else if (!strcmp(key, "audiodatarate") &&
0 <= (int)(num_val * 1024.0))
flv->audio_bit_rate = num_val * 1024.0;
else if (!strcmp(key, "datastream")) {
AVStream *st = create_stream(s, AVMEDIA_TYPE_SUBTITLE);
if (!st)
return AVERROR(ENOMEM);
st->codecpar->codec_id = AV_CODEC_ID_TEXT;
} else if (!strcmp(key, "framerate")) {
flv->framerate = av_d2q(num_val, 1000);
if (vstream)
vstream->avg_frame_rate = flv->framerate;
} else if (flv->trust_metadata) {
if (!strcmp(key, "videocodecid") && vpar) {
int ret = flv_set_video_codec(s, vstream, num_val, 0);
if (ret < 0)
return ret;
} else if (!strcmp(key, "audiocodecid") && apar) {
int id = ((int)num_val) << FLV_AUDIO_CODECID_OFFSET;
flv_set_audio_codec(s, astream, apar, id);
} else if (!strcmp(key, "audiosamplerate") && apar) {
apar->sample_rate = num_val;
} else if (!strcmp(key, "audiosamplesize") && apar) {
apar->bits_per_coded_sample = num_val;
} else if (!strcmp(key, "stereo") && apar) {
apar->channels = num_val + 1;
apar->channel_layout = apar->channels == 2 ?
AV_CH_LAYOUT_STEREO :
AV_CH_LAYOUT_MONO;
} else if (!strcmp(key, "width") && vpar) {
vpar->width = num_val;
} else if (!strcmp(key, "height") && vpar) {
vpar->height = num_val;
}
}
}
if (amf_type == AMF_DATA_TYPE_STRING) {
if (!strcmp(key, "encoder")) {
int version = -1;
if (1 == sscanf(str_val, "Open Broadcaster Software v0.%d", &version)) {
if (version > 0 && version <= 655)
flv->broken_sizes = 1;
}
} else if (!strcmp(key, "metadatacreator") && !strcmp(str_val, "MEGA")) {
flv->broken_sizes = 1;
}
}
}
if (amf_type == AMF_DATA_TYPE_OBJECT && s->nb_streams == 1 &&
((!apar && !strcmp(key, "audiocodecid")) ||
(!vpar && !strcmp(key, "videocodecid"))))
s->ctx_flags &= ~AVFMTCTX_NOHEADER; //If there is either audio/video missing, codecid will be an empty object
if (!strcmp(key, "duration") ||
!strcmp(key, "filesize") ||
!strcmp(key, "width") ||
!strcmp(key, "height") ||
!strcmp(key, "videodatarate") ||
!strcmp(key, "framerate") ||
!strcmp(key, "videocodecid") ||
!strcmp(key, "audiodatarate") ||
!strcmp(key, "audiosamplerate") ||
!strcmp(key, "audiosamplesize") ||
!strcmp(key, "stereo") ||
!strcmp(key, "audiocodecid") ||
!strcmp(key, "datastream"))
return 0;
s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
if (amf_type == AMF_DATA_TYPE_BOOL) {
av_strlcpy(str_val, num_val > 0 ? "true" : "false",
sizeof(str_val));
av_dict_set(&s->metadata, key, str_val, 0);
} else if (amf_type == AMF_DATA_TYPE_NUMBER) {
snprintf(str_val, sizeof(str_val), "%.f", num_val);
av_dict_set(&s->metadata, key, str_val, 0);
} else if (amf_type == AMF_DATA_TYPE_STRING)
av_dict_set(&s->metadata, key, str_val, 0);
}
return 0;
}
#define TYPE_ONTEXTDATA 1
#define TYPE_ONCAPTION 2
#define TYPE_ONCAPTIONINFO 3
#define TYPE_UNKNOWN 9
static int flv_read_metabody(AVFormatContext *s, int64_t next_pos)
{
FLVContext *flv = s->priv_data;
AMFDataType type;
AVStream *stream, *astream, *vstream;
AVStream av_unused *dstream;
AVIOContext *ioc;
int i;
// only needs to hold the string "onMetaData".
// Anything longer is something we don't want.
char buffer[32];
astream = NULL;
vstream = NULL;
dstream = NULL;
ioc = s->pb;
// first object needs to be "onMetaData" string
type = avio_r8(ioc);
if (type != AMF_DATA_TYPE_STRING ||
amf_get_string(ioc, buffer, sizeof(buffer)) < 0)
return TYPE_UNKNOWN;
if (!strcmp(buffer, "onTextData"))
return TYPE_ONTEXTDATA;
if (!strcmp(buffer, "onCaption"))
return TYPE_ONCAPTION;
if (!strcmp(buffer, "onCaptionInfo"))
return TYPE_ONCAPTIONINFO;
if (strcmp(buffer, "onMetaData") && strcmp(buffer, "onCuePoint")) {
av_log(s, AV_LOG_DEBUG, "Unknown type %s\n", buffer);
return TYPE_UNKNOWN;
}
// find the streams now so that amf_parse_object doesn't need to do
// the lookup every time it is called.
for (i = 0; i < s->nb_streams; i++) {
stream = s->streams[i];
if (stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
vstream = stream;
flv->last_keyframe_stream_index = i;
} else if (stream->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
astream = stream;
if (flv->last_keyframe_stream_index == -1)
flv->last_keyframe_stream_index = i;
}
else if (stream->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
dstream = stream;
}
// parse the second object (we want a mixed array)
if (amf_parse_object(s, astream, vstream, buffer, next_pos, 0) < 0)
return -1;
return 0;
}
static int flv_read_header(AVFormatContext *s)
{
int flags;
FLVContext *flv = s->priv_data;
int offset;
int pre_tag_size = 0;
avio_skip(s->pb, 4);
flags = avio_r8(s->pb);
flv->missing_streams = flags & (FLV_HEADER_FLAG_HASVIDEO | FLV_HEADER_FLAG_HASAUDIO);
s->ctx_flags |= AVFMTCTX_NOHEADER;
offset = avio_rb32(s->pb);
avio_seek(s->pb, offset, SEEK_SET);
/* Annex E. The FLV File Format
* E.3 TheFLVFileBody
* Field Type Comment
* PreviousTagSize0 UI32 Always 0
* */
pre_tag_size = avio_rb32(s->pb);
if (pre_tag_size) {
av_log(s, AV_LOG_WARNING, "Read FLV header error, input file is not a standard flv format, first PreviousTagSize0 always is 0\n");
}
s->start_time = 0;
flv->sum_flv_tag_size = 0;
flv->last_keyframe_stream_index = -1;
return 0;
}
static int flv_read_close(AVFormatContext *s)
{
int i;
FLVContext *flv = s->priv_data;
for (i=0; inew_extradata[i]);
av_freep(&flv->keyframe_times);
av_freep(&flv->keyframe_filepositions);
return 0;
}
static int flv_get_extradata(AVFormatContext *s, AVStream *st, int size)
{
av_freep(&st->codecpar->extradata);
if (ff_get_extradata(s, st->codecpar, s->pb, size) < 0)
return AVERROR(ENOMEM);
return 0;
}
static int flv_queue_extradata(FLVContext *flv, AVIOContext *pb, int stream,
int size)
{
av_free(flv->new_extradata[stream]);
flv->new_extradata[stream] = av_mallocz(size +
AV_INPUT_BUFFER_PADDING_SIZE);
if (!flv->new_extradata[stream])
return AVERROR(ENOMEM);
flv->new_extradata_size[stream] = size;
avio_read(pb, flv->new_extradata[stream], size);
return 0;
}
static void clear_index_entries(AVFormatContext *s, int64_t pos)
{
int i, j, out;
av_log(s, AV_LOG_WARNING,
"Found invalid index entries, clearing the index.\n");
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
/* Remove all index entries that point to >= pos */
out = 0;
for (j = 0; j < st->nb_index_entries; j++)
if (st->index_entries[j].pos < pos)
st->index_entries[out++] = st->index_entries[j];
st->nb_index_entries = out;
}
}
static int amf_skip_tag(AVIOContext *pb, AMFDataType type)
{
int nb = -1, ret, parse_name = 1;
switch (type) {
case AMF_DATA_TYPE_NUMBER:
avio_skip(pb, 8);
break;
case AMF_DATA_TYPE_BOOL:
avio_skip(pb, 1);
break;
case AMF_DATA_TYPE_STRING:
avio_skip(pb, avio_rb16(pb));
break;
case AMF_DATA_TYPE_ARRAY:
parse_name = 0;
case AMF_DATA_TYPE_MIXEDARRAY:
nb = avio_rb32(pb);
case AMF_DATA_TYPE_OBJECT:
while(!pb->eof_reached && (nb-- > 0 || type != AMF_DATA_TYPE_ARRAY)) {
if (parse_name) {
int size = avio_rb16(pb);
if (!size) {
avio_skip(pb, 1);
break;
}
avio_skip(pb, size);
}
if ((ret = amf_skip_tag(pb, avio_r8(pb))) < 0)
return ret;
}
break;
case AMF_DATA_TYPE_NULL:
case AMF_DATA_TYPE_OBJECT_END:
break;
default:
return AVERROR_INVALIDDATA;
}
return 0;
}
static int flv_data_packet(AVFormatContext *s, AVPacket *pkt,
int64_t dts, int64_t next)
{
AVIOContext *pb = s->pb;
AVStream *st = NULL;
char buf[20];
int ret = AVERROR_INVALIDDATA;
int i, length = -1;
int array = 0;
switch (avio_r8(pb)) {
case AMF_DATA_TYPE_ARRAY:
array = 1;
case AMF_DATA_TYPE_MIXEDARRAY:
avio_seek(pb, 4, SEEK_CUR);
case AMF_DATA_TYPE_OBJECT:
break;
default:
goto skip;
}
while (array || (ret = amf_get_string(pb, buf, sizeof(buf))) > 0) {
AMFDataType type = avio_r8(pb);
if (type == AMF_DATA_TYPE_STRING && (array || !strcmp(buf, "text"))) {
length = avio_rb16(pb);
ret = av_get_packet(pb, pkt, length);
if (ret < 0)
goto skip;
else
break;
} else {
if ((ret = amf_skip_tag(pb, type)) < 0)
goto skip;
}
}
if (length < 0) {
ret = AVERROR_INVALIDDATA;
goto skip;
}
for (i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
break;
}
if (i == s->nb_streams) {
st = create_stream(s, AVMEDIA_TYPE_SUBTITLE);
if (!st)
return AVERROR(ENOMEM);
st->codecpar->codec_id = AV_CODEC_ID_TEXT;
}
pkt->dts = dts;
pkt->pts = dts;
pkt->size = ret;
pkt->stream_index = st->index;
pkt->flags |= AV_PKT_FLAG_KEY;
skip:
avio_seek(s->pb, next + 4, SEEK_SET);
return ret;
}
static int resync(AVFormatContext *s)
{
FLVContext *flv = s->priv_data;
int64_t i;
int64_t pos = avio_tell(s->pb);
for (i=0; !avio_feof(s->pb); i++) {
int j = i & (RESYNC_BUFFER_SIZE-1);
int j1 = j + RESYNC_BUFFER_SIZE;
flv->resync_buffer[j ] =
flv->resync_buffer[j1] = avio_r8(s->pb);
if (i > 22) {
unsigned lsize2 = AV_RB32(flv->resync_buffer + j1 - 4);
if (lsize2 >= 11 && lsize2 + 8LL < FFMIN(i, RESYNC_BUFFER_SIZE)) {
unsigned size2 = AV_RB24(flv->resync_buffer + j1 - lsize2 + 1 - 4);
unsigned lsize1 = AV_RB32(flv->resync_buffer + j1 - lsize2 - 8);
if (lsize1 >= 11 && lsize1 + 8LL + lsize2 < FFMIN(i, RESYNC_BUFFER_SIZE)) {
unsigned size1 = AV_RB24(flv->resync_buffer + j1 - lsize1 + 1 - lsize2 - 8);
if (size1 == lsize1 - 11 && size2 == lsize2 - 11) {
avio_seek(s->pb, pos + i - lsize1 - lsize2 - 8, SEEK_SET);
return 1;
}
}
}
}
}
return AVERROR_EOF;
}
static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
{
FLVContext *flv = s->priv_data;
int ret, i, size, flags;
enum FlvTagType type;
int stream_type=-1;
int64_t next, pos, meta_pos;
int64_t dts, pts = AV_NOPTS_VALUE;
int av_uninit(channels);
int av_uninit(sample_rate);
AVStream *st = NULL;
int last = -1;
int orig_size;
retry:
/* pkt size is repeated at end. skip it */
pos = avio_tell(s->pb);
//解析Tag Header====
//Tag类型
type = (avio_r8(s->pb) & 0x1F);
orig_size =
//Datasize数据大小
size = avio_rb24(s->pb);
flv->sum_flv_tag_size += size + 11;
//Timstamp时间节
dts = avio_rb24(s->pb);
dts |= (unsigned)avio_r8(s->pb) << 24;
av_log(s, AV_LOG_TRACE, "type:%d, size:%d, last:%d, dts:%"PRId64" pos:%"PRId64"\n", type, size, last, dts, avio_tell(s->pb));
if (avio_feof(s->pb))
return AVERROR_EOF;
//StreamID
avio_skip(s->pb, 3); /* stream id, always 0 */
flags = 0;
if (flv->validate_next < flv->validate_count) {
int64_t validate_pos = flv->validate_index[flv->validate_next].pos;
if (pos == validate_pos) {
if (FFABS(dts - flv->validate_index[flv->validate_next].dts) <=
VALIDATE_INDEX_TS_THRESH) {
flv->validate_next++;
} else {
clear_index_entries(s, validate_pos);
flv->validate_count = 0;
}
} else if (pos > validate_pos) {
clear_index_entries(s, validate_pos);
flv->validate_count = 0;
}
}
if (size == 0) {
ret = FFERROR_REDO;
goto leave;
}
next = size + avio_tell(s->pb);
if (type == FLV_TAG_TYPE_AUDIO) {
// Type是音频
stream_type = FLV_STREAM_TYPE_AUDIO;
//Tag Data的第一个字节
flags = avio_r8(s->pb);
size--;
} else if (type == FLV_TAG_TYPE_VIDEO) {
stream_type = FLV_STREAM_TYPE_VIDEO;
flags = avio_r8(s->pb);
size--;
if ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_VIDEO_INFO_CMD)
goto skip;
} else if (type == FLV_TAG_TYPE_META) {
stream_type=FLV_STREAM_TYPE_DATA;
if (size > 13 + 1 + 4) { // Header-type metadata stuff
int type;
meta_pos = avio_tell(s->pb);
type = flv_read_metabody(s, next);
if (type == 0 && dts == 0 || type < 0 || type == TYPE_UNKNOWN) {
if (type < 0 && flv->validate_count &&
flv->validate_index[0].pos > next &&
flv->validate_index[0].pos - 4 < next
) {
av_log(s, AV_LOG_WARNING, "Adjusting next position due to index mismatch\n");
next = flv->validate_index[0].pos - 4;
}
goto skip;
} else if (type == TYPE_ONTEXTDATA) {
avpriv_request_sample(s, "OnTextData packet");
return flv_data_packet(s, pkt, dts, next);
} else if (type == TYPE_ONCAPTION) {
return flv_data_packet(s, pkt, dts, next);
}
avio_seek(s->pb, meta_pos, SEEK_SET);
}
} else {
av_log(s, AV_LOG_DEBUG,
"Skipping flv packet: type %d, size %d, flags %d.\n",
type, size, flags);
skip:
avio_seek(s->pb, next, SEEK_SET);
ret = FFERROR_REDO;
goto leave;
}
/* skip empty data packets */
if (!size) {
ret = FFERROR_REDO;
goto leave;
}
/* now find stream */
for (i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (stream_type == FLV_STREAM_TYPE_AUDIO) {
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
(s->audio_codec_id || flv_same_audio_codec(st->codecpar, flags)))
break;
} else if (stream_type == FLV_STREAM_TYPE_VIDEO) {
if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
(s->video_codec_id || flv_same_video_codec(st->codecpar, flags)))
break;
} else if (stream_type == FLV_STREAM_TYPE_DATA) {
if (st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE)
break;
}
}
if (i == s->nb_streams) {
static const enum AVMediaType stream_types[] = {AVMEDIA_TYPE_VIDEO, AVMEDIA_TYPE_AUDIO, AVMEDIA_TYPE_SUBTITLE};
st = create_stream(s, stream_types[stream_type]);
if (!st)
return AVERROR(ENOMEM);
}
av_log(s, AV_LOG_TRACE, "%d %X %d \n", stream_type, flags, st->discard);
if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY ||
stream_type == FLV_STREAM_TYPE_AUDIO))
av_add_index_entry(st, pos, dts, size, 0, AVINDEX_KEYFRAME);
if ( (st->discard >= AVDISCARD_NONKEY && !((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY || (stream_type == FLV_STREAM_TYPE_AUDIO)))
||(st->discard >= AVDISCARD_BIDIR && ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_DISP_INTER && (stream_type == FLV_STREAM_TYPE_VIDEO)))
|| st->discard >= AVDISCARD_ALL
) {
avio_seek(s->pb, next, SEEK_SET);
ret = FFERROR_REDO;
goto leave;
}
// if not streamed and no duration from metadata then seek to end to find
// the duration from the timestamps
if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
(!s->duration || s->duration == AV_NOPTS_VALUE) &&
!flv->searched_for_end) {
int size;
const int64_t pos = avio_tell(s->pb);
// Read the last 4 bytes of the file, this should be the size of the
// previous FLV tag. Use the timestamp of its payload as duration.
int64_t fsize = avio_size(s->pb);
retry_duration:
avio_seek(s->pb, fsize - 4, SEEK_SET);
size = avio_rb32(s->pb);
if (size > 0 && size < fsize) {
// Seek to the start of the last FLV tag at position (fsize - 4 - size)
// but skip the byte indicating the type.
avio_seek(s->pb, fsize - 3 - size, SEEK_SET);
if (size == avio_rb24(s->pb) + 11) {
uint32_t ts = avio_rb24(s->pb);
ts |= avio_r8(s->pb) << 24;
if (ts)
s->duration = ts * (int64_t)AV_TIME_BASE / 1000;
else if (fsize >= 8 && fsize - 8 >= size) {
fsize -= size+4;
goto retry_duration;
}
}
}
avio_seek(s->pb, pos, SEEK_SET);
flv->searched_for_end = 1;
}
if (stream_type == FLV_STREAM_TYPE_AUDIO) {
int bits_per_coded_sample;
channels = (flags & FLV_AUDIO_CHANNEL_MASK) == FLV_STEREO ? 2 : 1;
sample_rate = 44100 << ((flags & FLV_AUDIO_SAMPLERATE_MASK) >>
FLV_AUDIO_SAMPLERATE_OFFSET) >> 3;
bits_per_coded_sample = (flags & FLV_AUDIO_SAMPLESIZE_MASK) ? 16 : 8;
if (!st->codecpar->channels || !st->codecpar->sample_rate ||
!st->codecpar->bits_per_coded_sample) {
st->codecpar->channels = channels;
st->codecpar->channel_layout = channels == 1
? AV_CH_LAYOUT_MONO
: AV_CH_LAYOUT_STEREO;
st->codecpar->sample_rate = sample_rate;
st->codecpar->bits_per_coded_sample = bits_per_coded_sample;
}
if (!st->codecpar->codec_id) {
flv_set_audio_codec(s, st, st->codecpar,
flags & FLV_AUDIO_CODECID_MASK);
flv->last_sample_rate =
sample_rate = st->codecpar->sample_rate;
flv->last_channels =
channels = st->codecpar->channels;
} else {
AVCodecParameters *par = avcodec_parameters_alloc();
if (!par) {
ret = AVERROR(ENOMEM);
goto leave;
}
par->sample_rate = sample_rate;
par->bits_per_coded_sample = bits_per_coded_sample;
flv_set_audio_codec(s, st, par, flags & FLV_AUDIO_CODECID_MASK);
sample_rate = par->sample_rate;
avcodec_parameters_free(&par);
}
} else if (stream_type == FLV_STREAM_TYPE_VIDEO) {
int ret = flv_set_video_codec(s, st, flags & FLV_VIDEO_CODECID_MASK, 1);
if (ret < 0)
return ret;
size -= ret;
} else if (stream_type == FLV_STREAM_TYPE_DATA) {
st->codecpar->codec_id = AV_CODEC_ID_TEXT;
}
//几种特殊的格式
if (st->codecpar->codec_id == AV_CODEC_ID_AAC ||
st->codecpar->codec_id == AV_CODEC_ID_H264 ||
st->codecpar->codec_id == AV_CODEC_ID_MPEG4) {
//对应AACPacketType或者AVCPacketType
int type = avio_r8(s->pb);
size--;
//H.264
if (st->codecpar->codec_id == AV_CODEC_ID_H264 || st->codecpar->codec_id == AV_CODEC_ID_MPEG4) {
// sign extension
//对应CompositionTime
int32_t cts = (avio_rb24(s->pb) + 0xff800000) ^ 0xff800000;
//计算PTS
pts = dts + cts;
if (cts < 0) { // dts might be wrong
if (!flv->wrong_dts)
av_log(s, AV_LOG_WARNING,
"Negative cts, previous timestamps might be wrong.\n");
flv->wrong_dts = 1;
} else if (FFABS(dts - pts) > 1000*60*15) {
av_log(s, AV_LOG_WARNING,
"invalid timestamps %"PRId64" %"PRId64"\n", dts, pts);
dts = pts = AV_NOPTS_VALUE;
}
}
//如果编解码器是AAC或者H.264
if (type == 0 && (!st->codecpar->extradata || st->codecpar->codec_id == AV_CODEC_ID_AAC ||
st->codecpar->codec_id == AV_CODEC_ID_H264)) {
AVDictionaryEntry *t;
if (st->codecpar->extradata) {
if ((ret = flv_queue_extradata(flv, s->pb, stream_type, size)) < 0)
return ret;
ret = FFERROR_REDO;
goto leave;
}
if ((ret = flv_get_extradata(s, st, size)) < 0)
return ret;
/* Workaround for buggy Omnia A/XE encoder */
t = av_dict_get(s->metadata, "Encoder", NULL, 0);
if (st->codecpar->codec_id == AV_CODEC_ID_AAC && t && !strcmp(t->value, "Omnia A/XE"))
st->codecpar->extradata_size = 2;
//AAC
if (st->codecpar->codec_id == AV_CODEC_ID_AAC && 0) {
MPEG4AudioConfig cfg;
if (avpriv_mpeg4audio_get_config(&cfg, st->codecpar->extradata,
st->codecpar->extradata_size * 8, 1) >= 0) {
st->codecpar->channels = cfg.channels;
st->codecpar->channel_layout = 0;
if (cfg.ext_sample_rate)
st->codecpar->sample_rate = cfg.ext_sample_rate;
else
st->codecpar->sample_rate = cfg.sample_rate;
av_log(s, AV_LOG_TRACE, "mp4a config channels %d sample rate %d\n",
st->codecpar->channels, st->codecpar->sample_rate);
}
}
ret = FFERROR_REDO;
goto leave;
}
}
/* skip empty data packets */
if (!size) {
ret = FFERROR_REDO;
goto leave;
}
ret = av_get_packet(s->pb, pkt, size);
if (ret < 0)
return ret;
//设置PTS，DTS等
pkt->dts = dts;
pkt->pts = pts == AV_NOPTS_VALUE ? dts : pts;
pkt->stream_index = st->index;
pkt->pos = pos;
if (flv->new_extradata[stream_type]) {
uint8_t *side = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
flv->new_extradata_size[stream_type]);
if (side) {
memcpy(side, flv->new_extradata[stream_type],
flv->new_extradata_size[stream_type]);
av_freep(&flv->new_extradata[stream_type]);
flv->new_extradata_size[stream_type] = 0;
}
}
//标记上Keyframe
if (stream_type == FLV_STREAM_TYPE_AUDIO &&
(sample_rate != flv->last_sample_rate ||
channels != flv->last_channels)) {
flv->last_sample_rate = sample_rate;
flv->last_channels = channels;
ff_add_param_change(pkt, channels, 0, sample_rate, 0, 0);
}
if ( stream_type == FLV_STREAM_TYPE_AUDIO ||
((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY) ||
stream_type == FLV_STREAM_TYPE_DATA)
pkt->flags |= AV_PKT_FLAG_KEY;
leave:
last = avio_rb32(s->pb);
if (last != orig_size + 11 && last != orig_size + 10 &&
!avio_feof(s->pb) &&
(last != orig_size || !last) && last != flv->sum_flv_tag_size &&
!flv->broken_sizes) {
av_log(s, AV_LOG_ERROR, "Packet mismatch %d %d %d\n", last, orig_size + 11, flv->sum_flv_tag_size);
avio_seek(s->pb, pos + 1, SEEK_SET);
ret = resync(s);
av_packet_unref(pkt);
if (ret >= 0) {
goto retry;
}
}
return ret;
}
static int flv_read_seek(AVFormatContext *s, int stream_index,
int64_t ts, int flags)
{
FLVContext *flv = s->priv_data;
flv->validate_count = 0;
return avio_seek_time(s->pb, stream_index, ts, flags);
}
#define OFFSET(x) offsetof(FLVContext, x)
#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
{ "flv_metadata", "Allocate streams according to the onMetaData array", OFFSET(trust_metadata), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VD },
{ "missing_streams", "", OFFSET(missing_streams), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 0xFF, VD | AV_OPT_FLAG_EXPORT | AV_OPT_FLAG_READONLY },
{ NULL }
};
static const AVClass flv_class = {
.class_name = "flvdec",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
//FLV封装格式
AVInputFormat ff_flv_demuxer = {
.name = "flv",
.long_name = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"),
.priv_data_size = sizeof(FLVContext),
.read_probe = flv_probe,
.read_header = flv_read_header,
.read_packet = flv_read_packet,
.read_seek = flv_read_seek,
.read_close = flv_read_close,
.extensions = "flv",
.priv_class = &flv_class,
};
static const AVClass live_flv_class = {
.class_name = "live_flvdec",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
AVInputFormat ff_live_flv_demuxer = {
.name = "live_flv",
.long_name = NULL_IF_CONFIG_SMALL("live RTMP FLV (Flash Video)"),
.priv_data_size = sizeof(FLVContext),
.read_probe = live_flv_probe,
.read_header = flv_read_header,
.read_packet = flv_read_packet,
.read_seek = flv_read_seek,
.read_close = flv_read_close,
.extensions = "flv",
.priv_class = &live_flv_class,
.flags = AVFMT_TS_DISCONT
};