Record RTSP stream with FFmpeg libavformat
I'm trying to record RTSP stream from Axis camera with FFmpeg libavformat. I can grab video from files and then save it to another file, this is OK. But camera sends strange data, FPS is 100 and camera sends every 4th frame so result FPS is about 25. But libavformat set packets dts/pts for 90000 fps (default?) and new file stream has 100fps. Result is one hour video with only 100 frames.
Here is my code
#include <stdio.h>
#include <stdlib.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavformat/avio.h>
int main(int argc, char** argv) {
AVFormatContext* context = avformat_alloc_context();
int video_stream_index;
av_register_all();
avcodec_register_all();
avformat_network_init();
//open rtsp
if(avformat_open_input(&context, "rtsp://195.200.199.8/mpeg4/media.amp",NULL,NULL) != 0){
return EXIT_FAILURE;
}
if(avformat_find_stream_info(context,NULL) < 0){
return EXIT_FAILURE;
}
//search video stream
for(int i =0;i<context->nb_streams;i++){
if(context->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
video_stream_index = i;
}
AVPacket packet;
av_init_packet(&packet);
//open output file
AVOutputFormat* fmt = av_guess_format(NULL,"test2.avi",NULL);
AVFormatContext* oc = avformat_alloc_context();
oc->oformat = fmt;
avio_open2(&oc->pb, "test.avi", AVIO_FLAG_WRITE,NULL,NULL);
AVStream* stream=NULL;
int cnt = 0;
//start reading packets from stream and write them to file
av_read_play(context);//play RTSP
while(av_read_frame(context,&packet)>=0 && cnt <100){//read 100 frames
if(packet.stream_index == video_stream_index){//packet is video
if(stream == NULL){//create stream in file
stream = avformat_new_stream(oc,context->streams[video_stream_index]->codec->codec);
avcodec_copy_context(stream->codec,context->streams[video_stream_index]->codec);
stream->sample_aspect_ratio = context->streams[video_stream_index]->codec->sample_aspect_ratio;
avformat_write_header(oc,NULL);
}
packet.stream_index = stream->id;
av_write_frame(oc,&packet);
cnt++;
}
av_free_packet(&packet);
av_init_packet(&packet);
}
av_read_pause(context);
av_write_trailer(oc);
avio_close(oc->pb);
avformat_free_context(oc);
return (EXIT_SUCCESS);
}
Result file is here: http://dl.dropbox.com/u/1243577/test.avi
Thanks for any advice
Answer
Here's how I do it. What I found was when receiving H264 the framerate in the stream is not correct. It sends 1/90000 Timebase. I skip initializing the new stream from the incoming stream and just copy certain parameters. The incoming r_frame_rate should be accurate if max_analyze_frames works correctly.
#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;
AVCodec *icodec;
AVStream *ist;
int i_index;
time_t timenow, timestart;
int got_key_frame = 0;
AVFormatContext *ofcx;
AVOutputFormat *ofmt;
AVCodecContext *occx;
AVCodec *ocodec;
AVStream *ost;
int o_index;
AVPacket pkt;
int ix;
const char *sProg = argv[ 0 ];
const char *sFileInput;
const char *sFileOutput;
int bRunTime;
if ( argc != 4 ) {
printf( "Usage: %s url outfile runtime\n", sProg );
return EXIT_FAILURE;
}
sFileInput = argv[ 1 ];
sFileOutput = argv[ 2 ];
bRunTime = atoi( argv[ 3 ] );
// 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 = -1;
for ( ix = 0; ix < ifcx->nb_streams; ix++ ) {
iccx = ifcx->streams[ ix ]->codec;
if ( iccx->codec_type == AVMEDIA_TYPE_VIDEO ) {
ist = ifcx->streams[ ix ];
i_index = ix;
break;
}
}
if ( i_index < 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 );
ofcx = avformat_alloc_context();
ofcx->oformat = ofmt;
avio_open2( &ofcx->pb, sFileOutput, AVIO_FLAG_WRITE, NULL, NULL );
// Create output stream
//ost = avformat_new_stream( ofcx, (AVCodec *) iccx->codec );
ost = avformat_new_stream( ofcx, NULL );
avcodec_copy_context( ost->codec, iccx );
ost->sample_aspect_ratio.num = iccx->sample_aspect_ratio.num;
ost->sample_aspect_ratio.den = iccx->sample_aspect_ratio.den;
// Assume r_frame_rate is accurate
ost->r_frame_rate = ist->r_frame_rate;
ost->avg_frame_rate = ost->r_frame_rate;
ost->time_base = av_inv_q( ost->r_frame_rate );
ost->codec->time_base = ost->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 );
av_dump_format( ofcx, 0, ofcx->filename, 1 );
timestart = timenow = get_time();
ix = 0;
//av_read_play(context);//play RTSP (Shouldn't need this since it defaults to playing on connect)
av_init_packet( &pkt );
while ( av_read_frame( ifcx, &pkt ) >= 0 && timenow - timestart <= bRunTime ) {
if ( pkt.stream_index == i_index ) { //packet is video
// Make sure we start on a key frame
if ( timestart == timenow && ! ( pkt.flags & AV_PKT_FLAG_KEY ) ) {
timestart = timenow = get_time();
continue;
}
got_key_frame = 1;
pkt.stream_index = ost->id;
pkt.pts = ix++;
pkt.dts = pkt.pts;
av_interleaved_write_frame( ofcx, &pkt );
}
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;
}