无编解码
#include <stdio.h>
#include <iostream>
using namespace std;
#define __STDC_CONSTANT_MACROS
#ifdef _WIN32
//Windows
extern "C"
{
#include "libavformat/avformat.h"
}
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavformat/avformat.h>
#ifdef __cplusplus
};
#endif
#endif
int main(int argc, char* argv[])
{
AVOutputFormat *ofmt = NULL;
//Input AVFormatContext and Output AVFormatContext
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVPacket pkt;
const char *in_filename, *out_filename;
int ret, i;
int frame_index=0;
in_filename = "1.mp4";//Input file URL
out_filename = "ws.avi";//Output file URL
av_register_all();
AVBitStreamFilterContext *filter = av_bitstream_filter_init("h264_mp4toannexb");
if (NULL == filter)
{
cout<<"filter init fail"<<endl;
}
av_register_bitstream_filter(filter->filter);
//Input
if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {//打开媒体文件
printf( "Could not open input file.");
goto end;
}
if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {//获取视频信息
printf( "Failed to retrieve input stream information");
goto end;
}
av_dump_format(ifmt_ctx, 0, in_filename, 0);
//初始化输出视频码流的AVFormatContext。
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++) {
//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);// 初始化AVStream
if (!out_stream) {
printf( "Failed allocating output stream\n");
ret = AVERROR_UNKNOWN;
goto end;
}
//关键：Copy the settings of AVCodecContext
if (avcodec_copy_context(out_stream->codec, in_stream->codec) < 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;
}
//Output information------------------
av_dump_format(ofmt_ctx, 0, out_filename, 1);
//Open output file
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);//打开输出文件。
if (ret < 0) {
printf( "Could not open output file '%s'", out_filename);
goto end;
}
}
//Write file header
if (avformat_write_header(ofmt_ctx, NULL) < 0) {
printf( "Error occurred when opening output file\n");
goto end;
}
while (1) {
AVStream *in_stream, *out_stream;
//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];
//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;
if (pkt.stream_index == 0) {
AVPacket fpkt = pkt;
int a = av_bitstream_filter_filter(filter,
out_stream->codec, NULL, &fpkt.data, &fpkt.size,
pkt.data, pkt.size, pkt.flags & AV_PKT_FLAG_KEY);
pkt.data = fpkt.data;
pkt.size = fpkt.size;
}
//Write
if (av_interleaved_write_frame(ofmt_ctx, &pkt) < 0) {//将AVPacket（存储视频压缩码流数据）写入文件
printf( "Error muxing packet\n");
break;
}
printf("Write %8d frames to output file\n",frame_index);
av_free_packet(&pkt);
frame_index++;
}
//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);
return 0;
}
