所需头文件和 main 文件
#include <iostream>
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/imgutils.h"
#include "libswscale/swscale.h"
};
#include <afxwin.h>
#pragma warning(disable:4996)
using namespace std;
int main()
{
Parser();
return 0;
}
函数定义
typedef struct
{
int startpos;
int endpos;
int len;
int code;
int startlen;
}FrameAna;
unsigned char m_outbuf[1024 * 1024];
typedef struct
{
uint8_t m_Head[4];
int m_len;
}FrameHead_t;
//yuv转为jpg
int tojpg(AVPacket *packet, AVFrame* pFrame, unsigned int stream_index, int width, int height)
{
char out_file[128] = "";
sprintf_s(out_file, sizeof(out_file), "D:\\jpg\\%03d.jpg", stream_index);//jpg图像输出路径
// 分配AVFormatContext对象
AVFormatContext* pFormatCtx = avformat_alloc_context();
// 设置输出文件格式
pFormatCtx->oformat = av_guess_format("mjpeg", NULL, NULL);
// 创建并初始化一个和该url相关的AVIOContext
if (avio_open(&pFormatCtx->pb, out_file, AVIO_FLAG_READ_WRITE) < 0)
{
printf("Couldn't open output file");
return -1;
}
// 构建一个新stream
AVStream* pAVStream = avformat_new_stream(pFormatCtx, 0);
if (pAVStream == NULL)
{
printf("Frame2JPG::avformat_new_stream error.");
return -1;
}
// 设置该stream的信息
AVCodecContext* pCodecCtx = pAVStream->codec;
pCodecCtx->codec_id = pFormatCtx->oformat->video_codec;
pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
pCodecCtx->pix_fmt = AV_PIX_FMT_YUVJ420P;
pCodecCtx->width = width;
pCodecCtx->height = height;
pCodecCtx->time_base.num = 1;
pCodecCtx->time_base.den = 25;
// 查找解码器
AVCodec* pCodec = avcodec_find_encoder(pCodecCtx->codec_id);
if (!pCodec)
{
printf("avcodec_find_encoder() error.");
return -1;
}
// 设置pCodecCtx的解码器为pCodec
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
{
printf("Could not open codec.");
return -1;
}
//Write Header
int ret = avformat_write_header(pFormatCtx, NULL);
if (ret < 0)
{
printf("avformat_write_header() error.\n");
return -1;
}
int y_size = pCodecCtx->width * pCodecCtx->height;
//Encode
// 给AVPacket分配足够大的空间
AVPacket pkt;
av_new_packet(&pkt, y_size * 3);
int got_picture = 0;
ret = avcodec_encode_video2(pCodecCtx, &pkt, pFrame, &got_picture);
if (ret < 0)
{
printf("avcodec_encode_video2() error.\n");
return -1;
}
if (got_picture == 1)
{
ret = av_write_frame(pFormatCtx, &pkt);
}
av_free_packet(&pkt);
//Write Trailer
av_write_trailer(pFormatCtx);
if (pAVStream)
{
avcodec_close(pAVStream->codec);
}
avio_close(pFormatCtx->pb);
avformat_free_context(pFormatCtx);
return 0;
}
将mp4文件转换为h264文件
//mp4中获取yuv
void Parser()
{
AVFormatContext *pFormatCtx;
int videoindex;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame;
uint8_t *out_buffer;
AVPacket *packet;
int ret, got_picture;
struct SwsContext *img_convert_ctx;
char filepath[] = "d:\\test.mp4";//要解析的mp4文件
FILE *fp_h264 = NULL;
FrameAna m_FrameInfo[1024];
int m_FrameIndex = 0;
fopen_s(&fp_h264, "d:\\output.h264", "wb+");//MP4输出成.h264文件
/* 初始化一个AVFormatContext ，并打开文件 */
pFormatCtx = avformat_alloc_context();
avformat_open_input(&pFormatCtx, filepath, NULL, NULL);
/* 获取视频文件信息 */
avformat_find_stream_info(pFormatCtx, NULL);
/* 查找视频的编号 */
videoindex = -1;
for (unsigned int i = 0; i < pFormatCtx->nb_streams; i++)
{
if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
{
videoindex = (int)i;
break;
}
if (videoindex == -1)
{
AfxMessageBox(L"can't find video,error!");
return;
}
}
/* 查找解码器 */
pCodecCtx = avcodec_alloc_context3(NULL);
avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoindex]->codecpar);
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
/* 打开解码器 */
avcodec_open2(pCodecCtx, pCodec, NULL);
pFrame = av_frame_alloc();
out_buffer = (uint8_t *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1));
packet = (AVPacket*)av_malloc(sizeof(AVPacket));
img_convert_ctx= sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
/* 获取流解析对象 */
unsigned char *h264_buf;
int h264_len;
AVBitStreamFilterContext* h264bsfc = av_bitstream_filter_init("h264_mp4toannexb");
int iNeedIFrame = 1;
int iDecoderCnt = 0;
while (av_read_frame(pFormatCtx, packet) >= 0)
{
/* 读取一帧压缩数据 */
if (packet->stream_index == videoindex)
{
/* 数据解码，可获取到YUV解码后数据 */
ret = avcodec_send_packet(pCodecCtx, packet);
if (ret < 0)
{
AfxMessageBox(L"Decoder one frame , Error !");
return;
}
got_picture = avcodec_receive_frame(pCodecCtx, pFrame);
if (0 == got_picture)
{
iDecoderCnt++;
if (nullptr != fp_h264)
{
fwrite(pFrame->data[0], 1, pFrame->width * pFrame->height, fp_h264);
fwrite(pFrame->data[1], 1, pFrame->width * pFrame->height / 4, fp_h264);
fwrite(pFrame->data[2], 1, pFrame->width * pFrame->height / 4, fp_h264);
//每一帧都调用tojpg函数转换为jpg图像
tojpg(packet,pFrame,(unsigned int)iDecoderCnt,pFrame->width,pFrame->height);
}
}
}
av_packet_unref(packet);
}
/* flush decoder */
/*当av_read_frame()循环退出的时候，实际上解码器中可能还包含剩余的几帧数据。因此需要通过“flush_decoder”将这几帧数据输出。“flush_decoder”功能简而言之即直接调用avcodec_decode_video2()获得AVFrame，而不再向解码器传递AVPacket。*/
while (1)
{
got_picture = avcodec_receive_frame(pCodecCtx, pFrame);
if (0 != got_picture)
break;
iDecoderCnt++;
}
sws_freeContext(img_convert_ctx);
/* 释放流解析对象 */
av_bitstream_filter_close(h264bsfc);
/* 关闭文件以及释放内存 */
fclose(fp_h264);
av_frame_free(&pFrame);
avcodec_close(pCodecCtx);
avformat_close_input(&pFormatCtx);
CString m_str;
m_str.Format(L"Get FrameCnt = %d Success !!\n", iDecoderCnt);
AfxMessageBox(m_str);
return;
}