[mythtv-users] Digital Audio Passthrough not working Mythtv 0.24-fixes

[James Courtier-Dutton]

On 11 November 2010 23:49, Jean-Yves Avenard <jyavenard at gmail.com> wrote:
> Hi
>
> On 11 November 2010 23:05, David Knight <dlknight at sdf.lonestar.org> wrote:
>> With "ALSA:default" = Device support up to 5.1 (AC3,DTS,)
>>
>> With "ALSA:default:CARD=NVidia" = HDA NVidia, ALC1200 Analog, Default
>> Audio Device, Device supports up to 2.0.
>
> They are one and the same...
> ALSA:default reports 5.1 because you've overridden the auto-detection
> so it shows what you've configured
>
>>
>> With "ALSA:iec958:CARD=NVidia,DEV=0" = HDA NVidia, ALC1200 Digital, IEC958
>> (S/PDIF) Digital Audio Output, Device supports up to 5.1 (digital output,
>> AC3,DTS,)
>
> So this is what your ALSA:default really supports: stereo only and is
> marked as an analog device
>
> That's why AC3 and DTS are disabled.
>
>>
>> I have other configurations available for HDMI and analog outputs (2.0 up
>> to 7.1).
>>>
>>
>> Well I've set the Audio output device to S/PDIF now and audio output is
>> working fine. I guess I need to enable the software mixer if I want to
>> regain volume control from within Myth?
>
> that's right
>
>>
>> Only time I use Analog is if I just want to output audio to the TV
>> speakers rather than the surround sound speakers. But I really should sort
>> out the HDMI output for that. Is there a possibility of enabling both
>> S/PDIF and HDMI output simultaneously for Myth?
>
> no at this stage. You can only select one output device.
>
> What I'm thinking of doing is if you have checked the override digital
> device; then the AC3 and DTS checkbox will always be available,
> despite what the main device report : this will provide support for
> what you are trying to achieve.
>
> Unfortunately, this will break the nice architecture we have in place
> right now for the sound framework as it will be a bit of a hack.. Not
> a fan of it.

Also, some hardware does not support it.
E.g. Output to spdif mutes the analogue output.
If you can run two instances of speaker-test, one for SPDIF and one
for HDMI and sound comes out of both, it might be worth trying.
There are other problems with outputting to two different devices at
the same time, they might be out of sync with each other.