[linux-dvb] Re: The origin of the pts ?

[Johannes Stezenbach <js@convergence.de>]

Peter Maersk-Moller wrote:
> 
> >>The reason I'm asking is that every now and then I seem to get
> >>a PTS of a frame belonging in the past. See the log below, where I
> >>receive data with a TT Budget (NOVA-s), broadcast with dvbstream,
> >>receive and decode with libmpeg2 (in mp4live).
> >Frames are sent in decoding order, not in display order.
> >(which is different in the presence of B-frames).
> 
> The TS stream is demuxed and fed to libmpeg2 as it is received.
> Decoded frames are read in display order. As you can see
> on the log, the jump backward in pts happens with minutes
> in-between.

Hm, I haven't read you mail thouroughly :-(
Maybe they use statistical multiplexing and their encoder creates
a weird GOP structure every now and then, which libmpeg2 doesn't
handle. You could try to look at it with MPEGanalizzatore
(from http://www.offeryn.de/dv.htm#mpgaz [runs fine with wine]).

The DTS of incoming frames must be ordered, PTSs are out of order
in the presence of B-frames, but frames are displayed when the
PTS is due, compared to the STC (which is synced to the PCR).

Johannes