最近项目开发中需要使用FFmpeg进行音视频的解码,在使用过程中遇到了一些问题对其进行记录。
FFmpeg版本:FFmpeg3.4.1 下载地址如下:https://download.csdn.net/download/lifei092/10670992
1、视频解码:
以下是示例代码(由于从项目中扣取出来,大致流程无问题,未进行验证可能会有一些小问题,现先记录后续再进行验证):
#include
#include
#include
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/channel_layout.h"
#include "libavutil/common.h"
#include "libavutil/imgutils.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
#include "libavutil/mathematics.h"
#include "libavutil/samplefmt.h"
};
#define ES_STREAM_VIDEO 1
#define ES_STREAM_AUDIO 2
#pragma comment(lib, "FFmpeg/lib/avcodec.lib")
#pragma comment(lib, "FFmpeg/lib/avformat.lib")
#pragma comment(lib, "FFmpeg/lib/avdevice.lib")
#pragma comment(lib, "FFmpeg/lib/avfilter.lib")
#pragma comment(lib, "FFmpeg/lib/avutil.lib")
#pragma comment(lib, "FFmpeg/lib/swresample.lib")
#pragma comment(lib, "FFmpeg/lib/swscale.lib")
typedef struct AVMediaPacket
{
BYTE* m_data[TL_NUM_DATA_POINTERS];
int m_linesize[TL_NUM_DATA_POINTERS];
BYTE* m_pBuf;
int m_buf_size;
int m_max_size;
int m_cur_size;//ES包使用
int m_packet_type;//0ES包 1Frame
//enum AVPixelFormat for video frames
//enum AVSampleFormat for audio
int m_pixel_format;
int m_channel_count;
LONGLONG m_channel_layout;
int m_nb_samples; // 单个声道音频样本个数
int m_sample_rate; // 音频采样率
int m_width;
int m_height;
/**
* The content of the picture is interlaced.
* - encoding: Set by user.
* - decoding: Set by libavcodec. (default 0)
*/
int m_interlaced_frame;//0逐行帧,1隔行帧
/**
* If the content is interlaced, is top field displayed first.
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/
int m_top_field_first;//0偶底场优先,1上奇场优先
int m_pict_type;
int m_es_stream_type;//是视频帧还是音频帧
LONGLONG m_pos;
LONGLONG m_origin_size;//原始ES包的字节数
LONGLONG m_dts;//ES包使用
LONGLONG m_pts;
LONGLONG m_origin_ts;
LONGLONG m_sys_pts;//转换成系统时间的pts(毫秒)
LONGLONG m_duration;//帧时长
LONGLONG m_sys_duration;//转换成系统时间的长度(毫秒)
int m_align;//数据的对齐方式
int m_scale_mod;//视频帧用到的变换方式(该帧是经过该变换方式得来的)
int m_stream_index;//同AVPacket的stream_index
int m_flags;//同AVPacket的flags
}AVMediaPacket;
/********** 查询FFmpeg支持的编解码器 ************/
void CheckEncoderDecoder()
{
char *info = (char *)malloc(40000);
memset(info, 0, 40000);
AVCodec *c_temp = av_codec_next(NULL);
while (c_temp != NULL)
{
if (c_temp->decode != NULL)
{
strcat(info, "[Decode]");
}
else
{
strcat(info, "[Encode]");
}
switch (c_temp->type)
{
case AVMEDIA_TYPE_VIDEO:
strcat(info, "[Video]");
break;
case AVMEDIA_TYPE_AUDIO:
strcat(info, "[Audeo]");
break;
default:
strcat(info, "[Other]");
break;
}
sprintf(info, "%s %10s\n", info, c_temp->name);
c_temp = c_temp->next;
}
puts(info);
free(info);
}
void InitMediaPacket(AVMediaPacket* pFrame,int nPacketType, int nEsStreamType)
{
for (int i = 0; i < TL_NUM_DATA_POINTERS; i++)
{
pFrame->m_data[i] = NULL; // 音视频数据
pFrame->m_linesize[i] = 0; // 每行数据的size
}
pFrame->m_pBuf = NULL; // 音视频数据指针
pFrame->m_buf_size = 0;
pFrame->m_max_size = 0;
pFrame->m_cur_size = 0;//ES包使用
pFrame->m_packet_type = nPacketType;//0ES包 1Frame
//enum AVPixelFormat for video frames
//enum AVSampleFormat for audio
pFrame->m_pixel_format = AV_PIX_FMT_NONE;
pFrame->m_channel_count = -1;
pFrame->m_channel_layout = -1;
pFrame->m_nb_samples = -1; // 单个声道音频样本个数
pFrame->m_sample_rate = -1; // 音频采样率
pFrame->m_width = -1;
pFrame->m_height = -1;
/**
* The content of the picture is interlaced.
* - encoding: Set by user.
* - decoding: Set by libavcodec. (default 0)
*/
pFrame->m_interlaced_frame = -1;//0逐行帧,1隔行帧
/**
* If the content is interlaced, is top field displayed first.
* - encoding: Set by user.
* - decoding: Set by libavcodec.
*/
pFrame->m_top_field_first = -1;//0偶底场优先,1上奇场优先
pFrame->m_pict_type = -1;
pFrame->m_es_stream_type = nEsStreamType;//是视频帧还是音频帧
pFrame->m_pos = -1;
pFrame->m_origin_size = -1;//原始ES包的字节数
pFrame->m_dts = -1;//ES包使用
pFrame->m_pts = -1;
pFrame->m_origin_ts = -1;
pFrame->m_sys_pts = -1;//转换成系统时间的pts(毫秒)
pFrame->m_duration = -1;//帧时长
pFrame->m_sys_duration = -1;//转换成系统时间的长度(毫秒)
pFrame->m_align = -1;//数据的对齐方式
pFrame->m_scale_mod = -1;//视频帧用到的变换方式(该帧是经过该变换方式得来的)
pFrame->m_stream_index = -1;//同AVPacket的stream_index
pFrame->m_flags = -1;//同AVPacket的flags
}
BOOL MallocMediaFrameBuf(AVMediaPacket* pFrame, int nBufLen)
{
if (nBufLen <= 0)
return FALSE;
for (int i = 0; i < TL_NUM_DATA_POINTERS; i++)
{
pFrame->m_data[i] = NULL; // 音视频数据
pFrame->m_linesize[i] = 0; // 每行数据的size
}
pFrame->m_pBuf = (BYTE*)malloc(nBufLen*sizeof(BYTE));
pFrame->m_buf_size = nBufLen;
if (pFrame->m_pBuf)
return TRUE;
else
return FALSE;
}
void ReleaseMediaPacket(AVMediaPacket* pFrame)
{
if (pFrame->m_pBuf)
{
free(pFrame->m_pBuf);
pFrame->m_pBuf = NULL;
}
}
int main()
{
const char *pInput_test = "E:\\C++\\VideoExaminationSystem\\TEST.gxf";
FILE *fout = fopen("E://test.yuv", "wb+");
AVMediaPacket src_frame;
InitMediaPacket(&src_frame, 1, ES_STREAM_VIDEO);
//1.注册所有组件
av_register_all();
CheckEncoderDecoder(); // 查询此FFmpeg版本支持的编解码器
//封装格式上下文,统领全局的结构体,保存了视频文件封装格式的相关信息
AVFormatContext *pFormatCtx = avformat_alloc_context(); //主要存储视音频封装格式中包含的信息
//2.打开输入视频文件,读取文件头信息
if (avformat_open_input(&pFormatCtx, pInput_test, NULL, NULL) != 0)
{
printf("%s", "无法打开输入视频文件");
return -1;
}
//3.获取视频文件信息
if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
{
printf("%s", "无法获取视频文件信息");
return -1;
}
//获取视频流的索引位置
//遍历所有类型的流(音频流、视频流、字幕流),找到视频流
int v_stream_idx = -1; // 视频流
//number of streams
for (int i = 0; i < pFormatCtx->nb_streams; i++)
{
//流的类型
if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
{
v_stream_idx = i; // 记录视频流索引
break;
}
}
if (v_stream_idx == -1)
{
printf("%s", "找不到视频流\n");
return -1;
}
//只有知道视频的编码方式,才能够根据编码方式去找到解码器
//获取视频流中的编解码上下文
AVCodecParameters *pCodecCtx = NULL;
AVCodec *pCodec = NULL;
AVCodecContext *pEnc = NULL;
AVPacket *packet = NULL;
AVFrame *pFrame = NULL;
int src_buf_len = -1;
pCodecCtx = pFormatCtx->streams[v_stream_idx]->codecpar;
//4.根据编解码上下文中的编码id查找对应的解码
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL)
{
printf("%s", "找不到视频解码器\n");
return -1;
}
pEnc = avcodec_alloc_context3(pCodec); // 初始化AVCodecContext,只是分配,还没打开
//5.打开解码器
if (avcodec_open2(pEnc, pCodec, NULL)<0)
{
printf("%s", "视频解码器无法打开\n");
return -1;
}
//输出视频信息
printf("视频的文件格式:%s\n", pFormatCtx->iformat->name);
printf("视频时长:%d\n", (pFormatCtx->duration) / 1000000);
printf("视频的宽高:%d,%d\n", pCodecCtx->width, pCodecCtx->height);
printf("视频解码器的名称:%s\n", pCodec->name);
std::cout << std::endl;
src_frame.m_pixel_format = pCodecCtx->format;
src_frame.m_width = pCodecCtx->width;
src_frame.m_height = pCodecCtx->height;
src_buf_len = av_image_get_buffer_size((AVPixelFormat)src_frame.m_pixel_format, src_frame.m_width, src_frame.m_height, 1);
if (!MallocMediaFrameBuf(&src_frame, src_buf_len))
{
return NULL;
}
// 根据视频格式填充结构体相关字段
av_image_fill_arrays(src_frame.m_data, src_frame.m_linesize, src_frame.m_pBuf, (AVPixelFormat)src_frame.m_pixel_format, src_frame.m_width, src_frame.m_height, 1);
//准备读取
//缓冲区,开辟空间,AVPacket用于存储一帧一帧的压缩数据(H264)
packet = (AVPacket*)av_malloc(sizeof(AVPacket));
//内存分配, AVFrame用于存储解码后的像素数据(YUV)
pFrame = av_frame_alloc();
int ret = -1;
int video_frame_count = 0;
//6.一帧一帧的读取压缩数据
while (av_read_frame(pFormatCtx, packet) >= 0)
{
//只要视频压缩数据(根据流的索引位置判断)
if (packet->stream_index == v_stream_idx && (VIDEO_DETECT_ONLY == nDetectFlag || AV_DETECT == nDetectFlag))
{
//7.解码一帧视频压缩数据,得到视频像素数据
ret = avcodec_send_packet(pEnc, packet);
if (ret < 0)
{
printf("%s", "解码错误");
return -1;
}
ret = avcodec_receive_frame(pEnc, pFrame);
if (!ret) // 0表示解码成功
{
for (int j = 0, cont = 0; j < TL_NUM_DATA_POINTERS && cont < src_buf_len; j++ )
{
int size = pFrame->linesize[j];
if (size <= 0)
break;
int radio = pFrame->linesize[0] / size;
for (int i = 0; i < pFrame->height / radio; i++)
{
memcpy(src_frame.m_pBuf + cont, pFrame->data[j] + i * size, pFrame->width / radio);
cont += pFrame->width / radio;
}
fwrite(src_frame->m_data[j], pFrame->width*pFrame->height/(radio*radio), 1, fout);
}
video_frame_count++;
printf("Decode Video Frame Number : %d\n", video_frame_count);
}
}
//释放资源
av_packet_unref(packet);
}
// Free the YUV frame
av_frame_free(&pFrame);
// Close the codecs
avcodec_close(pEnc);
// Close the video file
avformat_close_input(&pFormatCtx);
if(fout)
{
fclose(fout);
fout = NULL;
}
ReleaseMediaPacket(&src_frame);
std::cout << "I: Finish Video Scale." << std::endl;
system("pause");
return 0;
}
在调试过程中遇到了以下问题:
具体见上一篇博客:《FFmpeg中AVFrame中data与linesize的联系》https://blog.csdn.net/lifei092/article/details/82684217