Hello,
I am using FFMpeg to decode RTP streams specified by a SDP file.
Specifically I have the following SDP file:
v=0
o=- 15079605070653109974 15079605070653109974 IN IP4 lap-mair
s=Unnamed
i=N/A
c=IN IP4 10.153.199.134
t=0 0
a=tool:vlc 1.1.4
a=recvonly
a=type:broadcast
a=charset:UTF-8
m=audio 1234 RTP/AVP 96
b=AS:16
b=RR:0
a=rtpmap:96 mpeg4-generic/48000/2
a=fmtp:96 streamtype=5; profile-level-id=15; mode=AAC-hbr; config=1190;
SizeLength=13; IndexLength=3; IndexDeltaLength=3; Profile=1;
m=video 1236 RTP/AVP 97
b=AS:32
b=RR:0
a=rtpmap:97 H264/90000
a=fmtp:97
packetization-mode=1;profile-level-id=64000c;sprop-parameter-sets=Z2QADKwkpAeCP6wEQAAAAwBAAAAFI8UKkg==,aMvMsiw=;
FFMpeg first probes the streams and then starts playing them. However
after a few seconds of playback it stops getting video packets and only
gets audio packets. I have tried to figure out where the video packets
are lost, but I could not find it. The funny thing is, when i do not
decode audio packets i will get the video packets just fine. I am
wondering if avcodec_decode_audio3 sets some strange options that breaks
the receiving of the video packets. The code I am using is the following:
// Open video file
int ert = av_open_input_file(&format_ctx, file, NULL, 0, NULL);
if(ert!=0){
return; // Couldn't open file
}
// Retrieve stream information
ert = av_find_stream_info(ctx->format_ctx);
if(ert<0){
return; // Couldn't find stream information
}
// PREPARE VIDEO
// Find the first video stream
video_stream=-1;
int i;
for(i=0; i<ctx->format_ctx->nb_streams; i++)
if(&format_ctx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO) {
video_stream=i;
break;
}
ctx->audio_stream=-1;
for(i=0; i<ctx->format_ctx->nb_streams; i++)
if(&format_ctx->streams[i]->codec->codec_type==CODEC_TYPE_AUDIO) {
audio_stream=i;
break;
}
.......
while(1){
av_init_packet(&packet);
// Read frames and put them into the queue
if(av_read_frame(ctx->format_ctx, &packet)<0) {
continue;
}
// Is this a packet from the video stream?
if(packet.stream_index==video_stream) {
queue_put(ctx->video_queue, &packet);
}else if(packet.stream_index == audio_stream){
decoded_buf = (uint16_t *)audio_buf;
int read = 0;
// get packet from queue
while(packet.size > 0){
audio_buf_size = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2 - read;
len1 = avcodec_decode_audio3(ctx->audio_codec_ctx,
decoded_buf, &audio_buf_size, &packet);
if(len1 < 0) {
// if error, skip frame
break;
}
packet.data += len1;
packet.size -= len1;
decoded_buf += audio_buf_size;
read += audio_buf_size;
}
}
}
I have tried to solve the problem for several days now but I could not
come up with a solution. When i use the same code to play a local video
file the video playback works just fine.
Any hints on a solution for the problem are appreciated.
Thanks
Thomas
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