[mythtv-users] MythTV 0.24 HDMI audio problem

Jarod Wilson jarod at wilsonet.com
Sun Dec 26 04:17:31 UTC 2010

On Dec 25, 2010, at 10:17 PM, Jean-Yves Avenard wrote:

> On 26 December 2010 13:48, Jarod Wilson <jarod at wilsonet.com> wrote:
>> actually does the right thing. Still with the "Channels count non available"
>> when trying the same -D option to aplay, which sounds like either an aplay
>> or alsa driver bug to me.
> alsa bug in kernel >= 2.6.36

Well, this was with a kernel... And I've have to go back and
check to see how things behave with a 2.6.32-based kernel, but things
may well work the same there...

> the edid can now report how many lpcm channels are reported, for some
> amp however, like my SP32, it only reports the maximum number of
> channels available.
> alsa tried to be too smart and always assumed the minimum channels
> were also reported.

Not seeing any eld file here, unfortunately. I'll experiment with some
newer kernels and the alsa git trees this week though.

> Note that if you're using ALSA drivers from git, including alsa-lib,
> it's much easier to specify the hdmi device which also works for
> passthrough (passthrough won't work if you're using hw:x:y as you
> can't set the iecbit)
> hdmi:CARD=NVidia,DEV=x

The above works perfectly on my ion hardware (and happy days, I've
managed to resuscitate my asrock ion330 ht-bd box...), and yeah, that
is what I'm ultimately going for with the discrete card as well.

I'm actually thinking I might go ahead and pick up a GT430 though. The
GT220 I've got has a massive heatsink that blocks the adjacent slot,
but I see a number of GT430 cards w/much smaller ones. They run about
the same cost as a GT220 and support more and better audio options...

> DEV=x will automatically use device = 3, device =7 etc...  not that
> the x isn't the same number as what's reported by aplay -L
> e.g.
> DEV=0 = hw:0,3
> DEV=1 = hw=0,7
> etc..

Discovered that tonight. Ugh.

> you know the kernel better than I do, but the instructions there on
> how to compile alsa.

Yeah, that part's no problem. :)

> http://www.mythtv.org/wiki/User_Manual:HDAudioPassthrough
> Apply the patch I provided earlier to alsa-kmirror

I think I saw that go by, but I'll have to dig it out of the archive.
Will see how much free time the wife and kids let me have this week to
poke at this... Also have a ton of lirc stuff to work on, and will
undoubtedly be roped into some multiplayer Halo: Reach with my son
(with dual consoles, the way its meant to be done). :D

Jarod Wilson
jarod at wilsonet.com

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