[mythtv-users] Can't get S/PDIF sound working

Michael T. Dean mtdean at thirdcontact.com
Sat Jul 23 12:19:06 EDT 2005

Phill Edwards wrote:

>I've just bought a S/PDIF header for my Gigabyte mobo and am having
>trouble getting any sound out of it.
>I've taken the Jarod's .asoundrc which in turn was taken from the
>DigitalSoundHowTo at
>http://www.mythtv.info/moin.cgi/DigitalSoundHowTo. Jarod said that he
>only had to change 4 lines to get his working. The main thing seemed
>to be getting the device number right. The output of "aplay -l" gives
>[elm|~]$ aplay -l
>**** List of PLAYBACK Hardware Devices ****
>card 0: I82801DBICH4 [Intel 82801DB-ICH4], device 0: Intel ICH [Intel
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
>card 0: I82801DBICH4 [Intel 82801DB-ICH4], device 4: Intel ICH -
>IEC958 [Intel 82801DB-ICH4 - IEC958]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
>So I assume my S/PDIF device is number 4 - is that correct?

Your .asoundrc is correct.

>My problem is that none of the lines below produce any sound output
>when I connect the S/PDIF TOSLINK to my receiver:
>[elm|~]$ aplay -D digital pronounce_linux.au
>[elm|~]$ aplay pronounce_linux.au
>If I put the old analogue connection back in from the sound card to
>the receiver then I can get sound again, but I want to get this
>working so I can get Dolby from MythDVD.
>Does anyone know where I'm going wrong here?
Take Michael Carland's advice...  It's probably a setting in your 
receiver that is preventing you from using the signal (the receiver gets 
it, but it's not in the expected format, so the receiver cuts output to 
prevent destroying your speakers/making bad sounds).  The file you're 
playing will be sent as 48KHz PCM audio (digital), but your receiver may 
be expecting AC-3 or something.  You should be able to set it to 
auto-detect the sound format, which will allow you to use PCM and AC-3 
and ...

Good luck,

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