[FFmpeg-devel] [BUG] PCR, PTS drift for mpegts streams. Black screen on set-top box.

Olof Astrand olof_astrand
Thu Jun 4 20:11:04 CEST 2009

> > PCR is related to DTS, and yes this is a known problem. It should work
> > better in CBR mode, ie with rc_max_rate set and respected.
> Baptiste, can you please give the explicit command-line switches and 
> values to use for the CBR mode ?
> Also, an IP box is not likely to expect the stuffing used to reach the 
> constant bitrate, so it might not fully work, right ?
> FWIW, here in my company, this very problem makes us dependent on vlc 
> for TS muxing, which induces extra latency and instability (vlc has bugs 
> too, though fewer in the TS muxer :-P ). So it is THE dark spot about 
> ffmpeg which is absolutely perfect otherwise.

This works for us, however It is not CBR at all. Some set top boxes does not like it.

/usr/local/bin/ffmpeg -v 0 -f jack -ac 2 -i ffmpeg -ab 128000 -ac 2

-ar 44100 -acodec mp2 -f x11grab -r 25 -s pal -i :1.0 -vcodec

mpeg2video -b 8000000 -maxrate 12000000 -minrate 0 -bf 2 -i_qoffset 1

-bufsize 1835008 -packetsize 2048 -qscale 1 -threads 4 -f vob - | cvlc

--quiet --rc-fake-tty stream:///dev/stdin --sout 

#std{access=udp,mux=ts,dst=} :ttl=8 2>&1 >

/dev/null &

Maybe the problem is that vlc works for TS muxing.  
If it did not work then maybe someone would have more incentive to fix the it.


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