[linux-dvb] Re: AC3 output through soundcard (S-PDIF)

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

Matthias Weingart wrote:
> 
> On Tue, 19 Jun 2001, Klaus Schmidinger wrote:
> 
> > Ralf Bauer wrote:
> > >
> > > Now that VDR can record an AC3 stream, as far as I have understood Klaus,
> > > the next step for VDR would be to output the recorded AC3 data somehow on
> > > the soundcard. I wanted to help a little bit and did some research on this
> > > topic.
> >
> > Well, currently VDR can record two audio streams. You can, of course, set
> > the second audio PID to the AC3 PID, but I intend to introduce two additional
> > PIDs for that purpose. That way VDR can record two "normal" audio streams
> > plus two digital audio streams, in case all this is broadcast. The reason why
> > I need to have separate DPIDs ("Digital audio PID") is that I need to use
> > specific packet ids in the recorded PES file in order to filter out the
> > digital audio data when replaying.
> 
> Hi Klaus,
> 
> why not supporting "unlimited" number of audio tracks? You have still a
> comma separated list of audio-pids; that are handeld as apid1 and apid2 in
> the code. Why not accessing it as apid[0] and apid[1], and a loop
> for(i=0; i<apidcount; i++) every time you access it?
> It make sense - you can not imagine how your vdr is used in the future;
> and saves much work - you do not need to patch it if you want to store 5
> pids. Anyway there have to be specified what pid is used for ac3; and what
> is played...

VDR currently uses the audio IDs 0xC0 and 0xC1 for the "primary" and
"secondary" audio track. I'm planing on using 0xD0 and 0xD1 for the
primary and secondary digital audio tracks and introducing a new field
in the channels.conf file that holds the DPIDs ("Digital audio PIDs").
This can be expanded to a maximum of 16 analog and 16 digital audio
PIDs later, should this appear necessary. But first I want to get the
basic AC3 support running.

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
_______________________________________________________________


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