[alsa-devel] MCP7A HDMI passthrough audio Linux/ALSA

[Takashi Iwai]

At Fri, 03 Jul 2009 20:07:09 +0200,
Stéphane BERTHELOT wrote:
> 
> Takashi Iwai a écrit :
> > At Wed, 01 Jul 2009 11:18:15 +0200,
> > Stéphane BERTHELOT wrote:
> >   
> >> Takashi Iwai a écrit :
> >>
> >>     At Tue, 30 Jun 2009 22:51:03 +0200,
> >>     Stephane BERTHELOT wrote:
> >>
> >>     Hm, so apparently your TV doesn't accept non-audio format?
> >>     But TV accepted the ac3dec output with -R option, right?
> >>     (Make sure this -- otherwise ac3dec might have decoded by itself.)
> >>     
> >>     Basically, -R means to send the encoded an AC3 stream (packed in the
> >>     SPDIF format) without setting non-audio bit.  Whether non-audio bit is
> >>     1 or 0 is the only difference between -C and -R.  So, if -R really
> >>     works but not -C, it means that the non-audio bit must be off no
> >>     matter what you send.  Weird.
> >>
> >> I'm sure the TV only accepted -R and not -C (or -P) with the same ac3 file.
> >> But I'm confused since I was quite sure -R would *decode* ac3 to PCM and then
> >> send it in LPCM format.
> >>     
> >
> > Ah, yes, of course.  That's logical, then, that -R works.
> >
> > Hm, then it's an issue of receiver side?
> > Can Windows send the raw AC3 and TV decodes it properly?
> >
> >
> > Takashi
> >
> >
> >   
> Thanks you Takashi,
> 
> After investigating on the Windows side (damn!) I finally found that 
> with the latest Nvidia official HDMI audio out drivers I was also 
> receiving only stereo PCM.
> I'm very angry against Sharp since their TV set outputs AC3 when 
> switched on DVB tuner mode, it even offer "digital audio out settings" 
> on analog inputs (scart / component /...) but strangely this menu is no 
> more available when on an HDMI channel.
> I'm very upset about this, since this TV set is about 6 months old seems 
> already deprecated.
> I'm trying to get someone at Sharp service to make an upgrade to get 
> digital audio through HDMI to the optical output but I have little hope 
> about this. I still can't figure why they do that, is it a digital 
> entertainment system or not ? My old frist-gen dvd player does better ...
> 
> Thanks anyway for your help and if you can give me some hints about how 
> to convince Sharp to make an upgrade for this I will be welcome. I'm 
> pretty sure some other users have had the same kind of problems...
> 
> I now need either to buy an USB audio card with SPDIF out (or in/out) or 
> an HDMI switch (some have spdif out) or even a real new HD Audio Amp, 
> but this is getting more and more expensive ...

Hm, but you can basically decode on PC and send multi-channel LPCM
over HDMI.  Isn't it enough?  Or, maybe not, depending on the setup...


Takashi