ffmpeg探测网络流格式方法

最近遇到好几个人在问ffmpeg如何处理网络流，刚好前段时间也在做这方面，抽空整理了下，把主要代码发出来，希望对大家有用。为简单处理，我这里只简单介绍ＵＤＰ接收ＴＳ流，其实只要是socket接收的都可以类似处理。

/*
* main.c
*
* Created on: 2011-9-18
* Author: wudegang
*/

#include "utils.h"
#include <pthread.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>

UdpQueue recvqueue;
UdpParam udpParam;

//注册av_read_frame的回调函数，这里只是最简处理，实际应用中应加上出错处理，超时等待...
int read_data(void *opaque, uint8_t *buf, int buf_size) {
int size = buf_size;
int ret;
// printf("read data %d\n", buf_size);
do {
ret = get_queue(&recvqueue, buf, buf_size);
} while (ret);

// printf("read data Ok %d\n", buf_size);
return size;
}

#define BUF_SIZE 4096*500

int main(int argc, char** argv) {

init_queue(&recvqueue, 1024*500);

udpParam.argv = argv;
udpParam.queue = &recvqueue;
uint8_t *buf = av_mallocz(sizeof(uint8_t)*BUF_SIZE);


//UDP接收线程
pthread_t udp_recv_thread;
pthread_create(&udp_recv_thread, NULL, udp_ts_recv, &udpParam);
pthread_detach(udp_recv_thread);



av_register_all();

AVCodec *pVideoCodec, *pAudioCodec;
AVCodecContext *pVideoCodecCtx = NULL;
AVCodecContext *pAudioCodecCtx = NULL;
AVIOContext * pb = NULL;
AVInputFormat *piFmt = NULL;
AVFormatContext *pFmt = NULL;

//step1:申请一个AVIOContext
pb = avio_alloc_context(buf, BUF_SIZE, 0, NULL, read_data, NULL, NULL);
if (!pb) {
fprintf(stderr, "avio alloc failed!\n");
return -1;
}
//step2:探测流格式
if (av_probe_input_buffer(pb, &piFmt, "", NULL, 0, 0) < 0) {
fprintf(stderr, "probe failed!\n");
return -1;
} else {
fprintf(stdout, "probe success!\n");
fprintf(stdout, "format: %s[%s]\n", piFmt->name, piFmt->long_name);
}

pFmt = avformat_alloc_context();
pFmt->pb = pb; //step3:这一步很关键
//step4:打开流
if (avformat_open_input(&pFmt, "", piFmt, NULL) < 0) {
fprintf(stderr, "avformat open failed.\n");
return -1;
} else {
fprintf(stdout, "open stream success!\n");
}
//以下就和文件处理一致了
if (av_find_stream_info(pFmt) < 0) {
fprintf(stderr, "could not fine stream.\n");
return -1;
}

av_dump_format(pFmt, 0, "", 0);

int videoindex = -1;
int audioindex = -1;
for (int i = 0; i < pFmt->nb_streams; i++) {
if ( (pFmt->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
(videoindex < 0) ) {
videoindex = i;
}
if ( (pFmt->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) &&
(audioindex < 0) ) {
audioindex = i;
}
}

if (videoindex < 0 || audioindex < 0) {
fprintf(stderr, "videoindex=%d, audioindex=%d\n", videoindex, audioindex);
return -1;
}

AVStream *pVst,*pAst;
pVst = pFmt->streams[videoindex];
pAst = pFmt->streams[audioindex];

pVideoCodecCtx = pVst->codec;
pAudioCodecCtx = pAst->codec;

pVideoCodec = avcodec_find_decoder(pVideoCodecCtx->codec_id);
if (!pVideoCodec) {
fprintf(stderr, "could not find video decoder!\n");
return -1;
}
if (avcodec_open(pVideoCodecCtx, pVideoCodec) < 0) {
fprintf(stderr, "could not open video codec!\n");
return -1;
}

pAudioCodec = avcodec_find_decoder(pAudioCodecCtx->codec_id);
if (!pAudioCodec) {
fprintf(stderr, "could not find audio decoder!\n");
return -1;
}
if (avcodec_open(pAudioCodecCtx, pAudioCodec) < 0) {
fprintf(stderr, "could not open audio codec!\n");
return -1;
}

int got_picture;
uint8_t samples[AVCODEC_MAX_AUDIO_FRAME_SIZE*3/2];
AVFrame *pframe = avcodec_alloc_frame();
AVPacket pkt;
av_init_packet(&pkt);

while(1) {
if (av_read_frame(pFmt, &pkt) >= 0) {

if (pkt.stream_index == videoindex) {
fprintf(stdout, "pkt.size=%d,pkt.pts=%lld, pkt.data=0x%x.", pkt.size, pkt.pts,(unsigned int)pkt.data);
avcodec_decode_video2(pVideoCodecCtx, pframe, &got_picture, &pkt);
if (got_picture) {
fprintf(stdout, "decode one video frame!\n");
}
}else if (pkt.stream_index == audioindex) {
int frame_size = AVCODEC_MAX_AUDIO_FRAME_SIZE*3/2;
if (avcodec_decode_audio3(pAudioCodecCtx, (int16_t *)samples, &frame_size, &pkt) >= 0) {
fprintf(stdout, "decode one audio frame!\n");
}
}
av_free_packet(&pkt);
}
}

av_free(buf);
av_free(pframe);
free_queue(&recvqueue);
return 0;
}