[Libav-user] RTSP Audio/Video Synchronization
wm4
nfxjfg at googlemail.com
Tue Mar 24 21:11:44 CET 2015
On Tue, 24 Mar 2015 17:31:16 +0100
Alessio Volpe <alessio.volpe.av at gmail.com> wrote:
> Hi, this is my program:
>
> -------------------------------------------------------------
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <libavcodec/avcodec.h>
> #include <libavformat/avformat.h>
> #include <libavformat/avio.h>
> #include <sys/time.h>
>
> time_t get_time()
> {
> struct timeval tv;
>
> gettimeofday( &tv, NULL );
>
> return tv.tv_sec;
> }
>
> int main( int argc, char* argv[] )
> {
> AVFormatContext *ifcx = NULL;
> AVInputFormat *ifmt;
> AVCodecContext *iccx_video, *iccx_audio;
> AVCodec *icodec;
> AVStream *ist_video, *ist_audio;
> int i_index_video, i_index_audio;
> time_t timenow, timestart;
> int got_key_frame = 0;
>
> AVFormatContext *ofcx;
> AVOutputFormat *ofmt;
> AVCodecContext *occx;
> AVCodec *ocodec;
> AVStream *ost_video, *ost_audio;
> int o_index_video, o_index_audio;
>
> AVPacket pkt;
>
> int ix, ix_video, ix_audio;
>
> const char *sFileInput;
> const char *sFileOutput;
> int bRunTime;
>
> //Indirizzo RTSP
> sFileInput = "rtsp://10.4.1.175/media/video1";
>
> //File di output
> sFileOutput = "camera.avi";
>
> //Tempo di run dell'acquisizione
> bRunTime = 15; //Registra 15 secondi
>
> // Initialize library
> av_log_set_level( AV_LOG_DEBUG );
> av_register_all();
> avcodec_register_all();
> avformat_network_init();
>
> //
> // Input
> //
>
> //open rtsp
> if ( avformat_open_input( &ifcx, sFileInput, NULL, NULL) != 0 ) {
> printf( "ERROR: Cannot open input file\n" );
> return EXIT_FAILURE;
> }
>
> if ( avformat_find_stream_info( ifcx, NULL ) < 0 ) {
> printf( "ERROR: Cannot find stream info\n" );
> avformat_close_input( &ifcx );
> return EXIT_FAILURE;
> }
>
> snprintf( ifcx->filename, sizeof( ifcx->filename ), "%s", sFileInput );
>
> //search video stream
> i_index_video = -1;
> for ( ix = 0; ix < ifcx->nb_streams; ix++ ) {
> iccx_video = ifcx->streams[ ix ]->codec;
> if ( iccx_video->codec_type == AVMEDIA_TYPE_VIDEO ) {
> ist_video = ifcx->streams[ ix ];
> i_index_video = ix;
> break;
> }
> }
> if ( i_index_video < 0 ) {
> printf( "ERROR: Cannot find input video stream\n" );
> avformat_close_input( &ifcx );
> return EXIT_FAILURE;
> }
>
>
> //search audio stream
> i_index_audio = -1;
> for ( ix = 0; ix < ifcx->nb_streams; ix++ ) {
> iccx_audio = ifcx->streams[ ix ]->codec;
> if ( iccx_audio->codec_type == AVMEDIA_TYPE_AUDIO ) {
> ist_audio = ifcx->streams[ ix ];
> i_index_audio = ix;
> break;
> }
> }
> if ( i_index_audio < 0 ) {
> printf( "ERROR: Cannot find input video stream\n" );
> avformat_close_input( &ifcx );
> return EXIT_FAILURE;
> }
>
> //
> // Output
> //
>
> //open output file
> ofmt = av_guess_format( NULL, sFileOutput, NULL ); //Return the output
> format
> ofcx = avformat_alloc_context();
> ofcx->oformat = ofmt;
> avio_open2( &ofcx->pb, sFileOutput, AVIO_FLAG_WRITE, NULL, NULL );
>
> // Create Video output stream
> ost_video = avformat_new_stream( ofcx, NULL );
> ost_audio = avformat_new_stream( ofcx, NULL );
>
> avcodec_copy_context( ost_video->codec, iccx_video ); //Copia il codec
> dello stream di input
> avcodec_copy_context( ost_audio->codec, iccx_audio );
>
>
> ost_video->sample_aspect_ratio.num = iccx_video->sample_aspect_ratio.num;
> ost_video->sample_aspect_ratio.den = iccx_video->sample_aspect_ratio.den;
>
> // Assume r_frame_rate is accurate
> ost_video->r_frame_rate = ist_video->r_frame_rate;
> ost_video->avg_frame_rate = ost_video->r_frame_rate;
> ost_video->time_base = (AVRational){ost_video->r_frame_rate.den,
> ost_video->r_frame_rate.num}; //ost->time_base = av_inv_q(
> ost->r_frame_rate ); //error
> ost_video->codec->time_base = ost_video->time_base;
>
> // Create Audio output stream
> ost_audio->sample_aspect_ratio.num = iccx_audio->sample_aspect_ratio.num;
> ost_audio->sample_aspect_ratio.den = iccx_audio->sample_aspect_ratio.den;
>
>
> ost_audio->r_frame_rate = ist_audio->r_frame_rate;
> ost_audio->avg_frame_rate = ost_audio->r_frame_rate;
> ost_audio->time_base = (AVRational){ost_audio->r_frame_rate.den,
> ost_audio->r_frame_rate.num}; //ost->time_base = av_inv_q(
> ost->r_frame_rate ); //error
> ost_audio->codec->time_base = ost_audio->time_base;
>
> avformat_write_header( ofcx, NULL );
>
> snprintf( ofcx->filename, sizeof( ofcx->filename ), "%s", sFileOutput );
>
> //start reading packets from stream and write them to file
>
> av_dump_format( ifcx, 0, ifcx->filename, 0 ); //INFO INPUT
> av_dump_format( ofcx, 0, ofcx->filename, 1 ); //INFO OUTPUT
>
> timestart = timenow = get_time();
>
> ix_video = 0;
> ix_audio = 0;
>
> double video_pts, audio_pts;
>
> av_init_packet( &pkt );
>
> double audio_time, video_time;
>
> while ( av_read_frame( ifcx, &pkt ) >= 0 && timenow - timestart <=
> bRunTime ) { //&& (getchar() != 'q')){
> av_packet_rescale_ts(&pkt,
> ofcx->streams[i_index_video]->codec->time_base,
> ifcx->streams[i_index_video]->time_base);
> if ( pkt.stream_index == i_index_video ) { //packet is video
> //Make sure we start on a key frame - UN I-FRAME
> if ( timestart == timenow && ! ( pkt.flags & AV_PKT_FLAG_KEY ) ) {
> timestart = timenow = get_time();
> continue;
> }
> got_key_frame = 1;
>
> // video_pts = (double)ost_video->pts.val * ost_video->time_base.num /
> ost_video->time_base.den;
> // audio_pts = (double)ost_audio->pts.val * ost_audio->time_base.num /
> ost_audio->time_base.den;
>
> pkt.stream_index = ost_video->id;
> // /* prepare packet for muxing */
> // pkt.dts = av_rescale_q_rnd(pkt.dts,
> ofcx->streams[i_index_video]->codec->time_base,
> ofcx->streams[i_index_video]->time_base,
> AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
> // pkt.pts = av_rescale_q_rnd(pkt.pts,
> ofcx->streams[i_index_video]->codec->time_base,
> ofcx->streams[i_index_video]->time_base,
> AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
> // pkt.duration = av_rescale_q(pkt.duration,
> ofcx->streams[i_index_video]->codec->time_base,
> ofcx->streams[i_index_video]->time_base);
>
>
> pkt.pts = ix_video++;
> pkt.dts = pkt.pts;
>
> // /*Also, some streams have multiple ticks-per-frame, so if the video
> runs at double speed you might need to this right below the above line:
>
> // pkt.pts *= ifcx->streams[0]->codec->ticks_per_frame;
> // pkt.dts *= ifcx->streams[0]->codec->ticks_per_frame;
>
> //av_write_frame( ofcx, &pkt );
> av_interleaved_write_frame( ofcx, &pkt );
> }
> else{ //packet is audio
>
> pkt.pts = ix_video++;
> pkt.dts = pkt.pts;
>
> //av_write_frame( ofcx, &pkt );
> av_interleaved_write_frame( ofcx, &pkt );
>
> }
>
> //CICLO PER SINCRONIZZARE E SCRIVERE SU DISCO
>
> // printf("vpcopy[%d].pts = %d", i, vpcopy[i].pts);
> // printf("\n");
>
> // if(i == 30) {
> // for(j=0; j<30-1; j++)
> // {
> // min = j;
>
> // for(k=j+1; k<30; k++)
> // if(vpcopy[j].pts < vpcopy[min].pts) //cambiare questa
> condizione per invertire l'ordine
> // min = k;
>
> // temp=vpcopy[min];
> // vpcopy[min]=vpcopy[j];
> // vpcopy[j]=temp;
>
> // printf("vpcopy[%d].pts = %d", i, vpcopy[i].pts);
> // printf("\n");
>
> // av_interleaved_write_frame( ofcx, &vpcopy[j] );
> // }
> // i = 0;
> // }
>
>
> av_free_packet( &pkt );
> av_init_packet( &pkt );
>
> timenow = get_time();
> }
> av_read_pause( ifcx );
> av_write_trailer( ofcx );
> avio_close( ofcx->pb );
> avformat_free_context( ofcx );
>
> avformat_network_deinit();
>
> return EXIT_SUCCESS;
> }
>
> -------------------------------------------------------------
>
> I would like to synchronize the video and audio.
>
> How should I use the pts and dts?
It looks like you just want to receive the data and display it. This
should be helpful: http://dranger.com/ffmpeg/ (it starts with the
basics, but also touches A/V sync).
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