[vdr] Re: mpeg1 layer 2 (mp2) -> iec958 ?

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

On Tue, Oct 14, 2003 at 12:49:16PM +0200, Sven Goethel wrote:
> On Tuesday 14 October 2003 11:45, Dr. Werner Fink wrote:
> 
> >
> > Nevertheless it should be possible to embed mp2 audio
> > frames within an PCM frames each representing the length
> > the duration of the included mp2 frame.  
> > This for all
> > DVB cards which do not have a S/P-DIF out ... or sound cards
> > which lost the S/P-DIF in pin due to the vendors `kindness'.
> 
> yep .. a victim of the "kindness" of the vendors of a msi 845gl ..

Does this box really have only one S/P-DIF connector even
one the external side?  And is the CDROM only connected
analog to the onboard sound chip?

> 
> btw: if you use "loop through" iec958,
> how does the decoded mp2 signal reaches you SPDIF out ?
> is it plain PCM ? 

The data out of the S/P-DIF of the DVB card is linear PCM
stereo with 16bit@48kHz.  Beside this the PCM to S/P-DIF
encoder of the AV7110 or AV7111 is not able to set the
the status bit of the second 32bit transport word ... in
other words, it is not possible to mark the 16 bit data
therein as none audio.

> > And the question is: Are all A/V receivers and amplifiers
> > out there able to detect mp2 and switch on _automatically_
> > the mp2 decoder.
> 
> das true
> 
> but if your loop through solution works for decoded mp2,
> therefor plain PCM .. we may can pass software decoded mp2
> as plain PCM as well ?!?!

Should be possible ... in that case a fully software decoder
lib for mp2 is required.  Then the question about the license
and/or patents rises :-((

       Werner


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