[linux-dvb] Re: VDR suggestion - record to TS?

[Dr. Werner Fink <werner@suse.de>]

On Thu, May 03, 2001 at 12:52:32PM +0200, Jörg-Oliver Todamm wrote:
> Hi,
>  
> > I understand that this thread is about using the DVB hardware 
> > to *output*
> > the AC3 signal in a form useful for, e.g., an AC3 decoder.
> 
> You are right. I just found this:
> "IEC60958 (The S/PDIF) can carry normal audio and IEC61937 datastreams.
> IEC61937 datastreams can contain multichannel sound like MPEG2, AC3 or
> DTS. When IEC61937 datastrams are transferred, the bits which normally
> carry audio samples are replaced with the databits from the datastream
> and the headers of the S/PDIF signal. Channel-status information
> contains one bit (but 1) which tells if the data in S/PDIF frame is
> digital audio or some other data (DTS, AC3, MPEG audio etc.). This bit
> will tell normal digital audio equipments that they don't try to play
> back this data as they were audio samples. (would sound really horrible
> if this happens for some reason). 
> The equipments which can handle both normal audio and IEC61937 just look
> at those header bits to determine what to do with the received data. 
> (Source: http://www.epanorama.net/documents/audio/spdif.html)"
> 
> So if it is possible to send uncompressed audio to a DVB device and than
> to the SPDIF, it should also be possible to accept AC3 from an other
> device that is used for such data streams. The implementation sounds
> really simple and I would try it if I knew how to tweak the DVB driver
> code to test this one.

IMHO the question is: is the AV711X (or the firmeware) able to determine
this Channel-status information bit and send the raw data stream to the
S/PDIF?   If the firmeware is not able to do this, is there a way to do
this with the DVB driver? How this works for normal audio data (XXX -> PCM)?
What format does the XXX have (MPEG audio, MPEG-2 Layer I or II or III)?

Hmmm ... btw ... what does the jumber block J8 provide besides J2?


         Werner


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