[vdr] Re: A/V sync problems with new drivers

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

"Dr. Werner Fink" wrote:
> 
> On Tue, Apr 08, 2003 at 12:08:29PM +0200, Klaus Schmidinger wrote:
> > "Dr. Werner Fink" wrote:
> > > > And there is indeed a problem, for example the dutch channels in the
> > > > Canal digital package on astra 19.2.  These channels are broadcast with
> > > > PCR pid which is different to the video and audio pids and suffer a lot
> > > > from A/V sync problems under VDR.
> > > >
> > > > BVN is FTA at 12574 H on 19.2 E and is an example, with VPID 164, APID
> > > > 96 and PCR 175
> > > >
> > > > All of the other channels I receive seem to have PCR == VPID and these
> > > > no longer suffer from A/V sync problems....
> > >
> > > Is there a simple way for VDR to check if PCR == VPID || PCR == APID is
> > > true and otherwise set/record the PCR?
> >
> > How would it record the PCR?
> 
> AFAIK the PSI tables carried by the TS include also the Program Map Table
> which should indicate the pid used for the PCR.
> Maybe it is naive, but could it be possible that the vpid PES has to be remuxed
> to include the Program Clock Reference?

As far as I understand this (and that may still be very little ;-) the PCR information
can be broadcast either as part of the video (or audio) packets, or as separate
PCR packets. So far VDR simply receives VPID and APID (and maybe DPID) packets and
repacks them into PES. Apparently the PCR information from the video packets
is enough to handle all this. Problems arise if the broadcaster sends the PCR info
in separate packets, so that it is completely missing in the video packets.

I wonder if it would be possible (for the driver?) to transfer the PCR information
from the PCR packets into the video packets, so that in the end it delivers a Transport
Stream where the video packets again contain the PCR info. So the application (VDR)
wouldn't have to worry about processing PCR data. It might have to explicitly
tell the driver the PCR-PID, but that would be acceptable. However, what if
VDR wants to record more than one programme on the same transponder, but VPID and
PCR-PID are not the same? Will each programme have its own PCR-PID, or is that
the same for all programmes on one transponder (which, AFAICS would be the only reason
to have a separate PCR-PID in the first place)? If I'm not mistaken only _one_ PCR-PID
can be set.

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


-- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe vdr" as subject.