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

["Robert Schlabbach" <robert_s@gmx.net>]

From: "Peter Maersk-Moller" <peter@maersk-moller.net>
> Every now and then I seem to encounter PTS-values which seems to
> be less than their predecessor. As far as I remember, then the
> MPEG-2 TS is recreated by TT budget/Full card thus creating
> some of the header data on the-fly instead of just relaying data
> exact as it was recived. Is this correct ? If yes, is the PTS
> then recreated by the DVB card or is it just relayed as-is ?

TT *budget* cards deliver the stream unaltered. Only TT "premium" cards
need to re-create parts of the TS.

> 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).

Since you have a budget card, there must be a bug somewhere in the chain -
either the broadcaster is already delivering erroneous PTS, or maybe
libmpeg2 is buggy.

> Assuming libmpeg2 is decoding correct (and that I use libmpeg2
> correct, could the *PTS fro mthe past* be caused by loosing data
> every now and then on tha satellite down-link ?

Packet loss should lead to continuity count errors. What are you using as
the demultiplexer? Make sure it reports continuity count errors...

Regards,
--
Robert Schlabbach
e-mail: robert_s@gmx.net
Berlin, Germany