[mythtv-users] alsa rate change on via8237 spdif

Michael T. Dean mtdean at thirdcontact.com
Fri Jun 22 08:31:19 UTC 2007


On 06/22/2007 03:54 AM, Robin Gilks wrote:
>> If the above description doesn't work, use the ALSA configuration from
>> the wiki and set digital-hw to:
>>
>> pcm.digital-hw {
>>   type hw
>>   card 0
>>   # The default value for device is 0, so no need to specify
>>   device 0
>>   subdevice 3
>> }
>>
>> and IEC958 unmuted, IEC958 Playback AC97-SPSA on 100 ("full" volume in
>> alsamixer), IEC958 Playback Source on IEC958 In.  Then set up Myth to
>> use ALSA:digital or ALSA:mixed-digital.
>>
>> amixer sset 'IEC958' unmute
>> amixer sset 'IEC958 Output' unmute
>> amixer sset 'IEC958 Playback AC97-SPSA' 3
>> amixer sset 'IEC958 Playback Source' 'IEC958 In'
>>
>> At least one of the two configurations will work.  I.e. device should be
>> 0 and subdevice should be either 0 (default) or 3 in digital-hw.  You
>> should use the configuration file from the wiki, where the only
>> modification is to the device (and possibly adding a subdevice) for
>> digital-hw.  Then specify either ALSA:digital or ALSA:mixed-digital as
>> your "Audio output device" in Myth.
>>
>> The IEC958 settings will differ depending on which approach you use, so
>> ensure they're as specified.
>>
>> If both approaches work, use the second as it may allow you to do nice
>> things like 32kHz or 44.1kHz AC-3 passthrough (but doing so would
>> require additional plumbing), which you probably couldn't do with the
>> first.
> Major problem Mike...
> media ~ # amixer sset 'IEC958 Playback Source' 'PCM'
> amixer: Unable to find simple control 'IEC958 Playback Source',0
...
> I've checked the options I have compiled into alsamixer in case its
> something obvious like no AC3 support (I'm using Gentoo) but no luck
> there.
>
>
> BTW - my nvidia system also complains in the same fashion:
> zeus # amixer sset 'IEC958 Playback Source' 'PCM'
> amixer: Unable to find simple control 'IEC958 Playback Source',0
>
> The list of controls I have on the 8237 is as follows (using a Via1617A
> codec according to alsamixer):
>   

OK, so that's the difference--it's not a Realtek CODEC.  Ignore the
IEC968 Playback Source (i.e. it's not relevant for your card).

I'd try the above approach (with subdevice 3 first).  If that doesn't
work, try the first approach I mentioned, but try both 0 and 3 for
AC97-SPSA.  (For all three tests, don't worry about IEC958 Playback Source).

Mike


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