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

[Takashi Iwai]

At Tue, 30 Jun 2009 22:51:03 +0200,
Stephane BERTHELOT wrote:
> 
> Takashi Iwai a écrit :
> 
>     At Tue, 30 Jun 2009 15:04:05 +0200,
>     Stéphane BERTHELOT wrote:
> 
>         Hi Takashi,
>         
>         Thanks for you answer.
>         I have the exact same problem and configuration than reported here 
>         https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4406
>         apart :
>         - I'm using a ION platform (Acer Revo R3600 but still MCP7A : 0x10de0007)
>         - I never get the Dolby Digital or DTS indicator illuminated on my Amp.
>         - My TV is a Sharp LC-52X20E
>         
>         I thought this was a known problem and than someone at Nvidia could 
>         provide the missing HDA Verbs, if you prefer I can post to the 
>         alsa-devel mailing list to investigate further.
>         I can get a alsa-info output tonight, though it's very very similar to 
>         the one in the bug report. (and Raymond was saying that we should get 
>         "PCM AC3" on digital outputs)
> 
>     Try ac3dec for a primary testing instead of mplayer.  It's included in
>     alsa-tools.
>     
>             % ac3dec -C -H foo.ac3
>     
>     Use the latest one so that it accespt -H option.
> 
>     Takashi
> 
> Thank you Takashi for taking time to review my problem. I cc'ed alsa-devel
> since I have more info now and maybe some other people have the same problem
> or already a workaround.
> 
> I'm attaching the output of alsa-info.sh with my mixer settings and after
> having run ac3dec -H -C file.ac3
> 
> It works with -R instead of -C but does not work with -C or with -P (consumer
> or pro)
> I also tried modifying settings using iecset (audio off / audio on and
> consumer/pro) and no combination seems to work.
> 
> When I play stereo LPCM my TV set plays sound and so does my Amp in PCM mode.
> When I try to play in AC3 mode (-C) my TV set says "incompatible format
> received" and both the TV and Amp stay silent.

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 may try again on XP/Vista tomorrow to be really sure it works on them.
> 
> When changing play mode AES0 changes from 0x00 to 0x02 and AES1 to AES3 stay
> the same (0x82,0x00,0x02 if I remember well)

Note that the setup you made before ac3dec will be overridden anyway.
And during ac3dec playback, the status bits are locked and can't be
changed by others.


Takashi