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

Baptiste Coudurier baptiste.coudurier
Wed Jun 3 20:51:48 CEST 2009


On 6/3/2009 8:17 AM, Olof Astrand wrote:
> Hello,
> I have been trying to get ffmpeg to stream a screen capture (x11grab)
> to a set top box. Unfortunately ffmpeg has not been so successful so 
> far. It seems like mpegtsenc.c does not set or calculate PCR
> correctly.
> I have not gone into the details yet but would really like some help
> or pointers  if someone is working on this problem, or know anything
> about it.
> When I set ts->cur_pcr to the current pts for the audio stream like
> this:
> +                if (pts != AV_NOPTS_VALUE) {
> +                 ts->cur_pcr = pts-90000;
> +               }
> Then at I get an image for a while, otherwise the image on the set
> top box is black.

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.

A fully working buffering model for the TS muxer is needed, patch very


Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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