下面贴上代码，代码是从FFmpeg的例子改编的，平台是VC2010。
/*
*最简单的基于FFmpeg的封装格式转换器
*Simplest FFmpeg Remuxer
*
*雷霄骅 Lei Xiaohua
*leixiaohua1020@126.com
*中国传媒大学/数字电视技术
*Communication University of China / Digital TV Technology
*http://blog.csdn.net/leixiaohua1020
*
*本程序实现了视频封装格式之间的转换。
*需要注意的是本程序并不改变视音频的编码格式。
*
* This software converts a media file from one container format
* to another container format without encoding/decoding video files.
*/
#include "stdafx.h"
extern "C"
{
#include "libavformat/avformat.h"
};
int _tmain(int argc, _TCHAR* argv[])
{
AVOutputFormat *ofmt = NULL;
//输入对应一个AVFormatContext，输出对应一个AVFormatContext
//（Input AVFormatContext and Output AVFormatContext）
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVPacket pkt;
const char *in_filename, *out_filename;
int ret, i;
if (argc < 3) {
printf("usage: %s input output\n"
"Remux a media file with libavformat and libavcodec.\n"
"The output format is guessed according to the file extension.\n"
"Modified by Lei Xiaohua, leixiaohua1020@126.com\n"
"Communication University of China / Digital TV Technology\n"
"http://blog.csdn.net/leixiaohua1020", argv[0]);
return 1;
}
in_filename = argv[1];//输入文件名（Input file URL）
out_filename = argv[2];//输出文件名（Output file URL）
av_register_all();
//输入（Input）
if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
printf( "Could not open input file.");
goto end;
}
if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
printf( "Failed to retrieve input stream information");
goto end;
}
av_dump_format(ifmt_ctx, 0, in_filename, 0);
//输出（Output）
avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
if (!ofmt_ctx) {
printf( "Could not create output context\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ofmt = ofmt_ctx->oformat;
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
//根据输入流创建输出流（Create output AVStream according to input AVStream）
AVStream *in_stream = ifmt_ctx->streams[i];
AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
if (!out_stream) {
printf( "Failed allocating output stream\n");
ret = AVERROR_UNKNOWN;
goto end;
}
//复制AVCodecContext的设置（Copy the settings of AVCodecContext）
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
if (ret < 0) {
printf( "Failed to copy context from input to output stream codec context\n");
goto end;
}
out_stream->codec->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
}
//输出一下格式------------------
av_dump_format(ofmt_ctx, 0, out_filename, 1);
//打开输出文件（Open output file）
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
if (ret < 0) {
printf( "Could not open output file ‘%s‘", out_filename);
goto end;
}
}
//写文件头（Write file header）
ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
printf( "Error occurred when opening output file\n");
goto end;
}
int frame_index=0;
while (1) {
AVStream *in_stream, *out_stream;
//获取一个AVPacket（Get an AVPacket）
ret = av_read_frame(ifmt_ctx, &pkt);
if (ret < 0)
break;
in_stream = ifmt_ctx->streams[pkt.stream_index];
out_stream = ofmt_ctx->streams[pkt.stream_index];
/* copy packet */
//转换PTS/DTS（Convert PTS/DTS）
pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
pkt.pos = -1;
//写入（Write）
ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
if (ret < 0) {
printf( "Error muxing packet\n");
break;
}
printf("Write %8d frames to output file\n",frame_index);
av_free_packet(&pkt);
frame_index++;
}
//写文件尾（Write file trailer）
av_write_trailer(ofmt_ctx);
end:
avformat_close_input(&ifmt_ctx);
/* close output */
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
avio_close(ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);
if (ret < 0 && ret != AVERROR_EOF) {
printf( "Error occurred.\n");
return -1;
}
return 0;
}
完整工程下载地址：
http://download.csdn.net/detail/leixiaohua1020/7323491
最简单的基于FFmpeg的封装格式转换器（无编解码）,布布扣,bubuko.com
原文：http://blog.csdn.net/leixiaohua1020/article/details/25422685
