[mythtv-users] Still no AC3 passthrough...

[Greg Arena]

Tried it just now. I renamed .asoundrc so MythTV wouldn't use it,
set the main audio output to "ALSA:default", and set the
passthrough device to "ALSA:spdif". Worked OK for SD channels,
but didn't work when I tried to watch something with AC3 data (HD
broadcast/DVD) - I got silence.

I see this message printed by mythfrontend every time I try this
with "ALSA:spdif" or "ALSA:iec958":

2007-10-12 18:41:38.056 Opening ALSA audio device 'spdif'.
ALSA lib confmisc.c:1105:(snd_func_refer) Unable to find
definition
'cards.CMI8738-MC6.pcm.iec958.3:CARD=0,AES0=4,AES1=130,AES2=0,AES
3=2'
ALSA lib conf.c:3479:(_snd_config_evaluate) function
snd_func_refer returned error: No such file or directory
ALSA lib conf.c:3947:(snd_config_expand) Evaluate error: No such
file or directory
ALSA lib pcm.c:2143:(snd_pcm_open_noupdate) Unknown PCM spdif
2007-10-12 18:41:38.058 AudioOutput Error: snd_pcm_open(spdif):
No such file or directory
2007-10-12 18:41:38.058 NVP: Disabling Audio, reason is:
snd_pcm_open(spdif): No such file or directory

Can anybody explain what this "Unable to find definition ..."
message means? 

________________________________

From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Eric Smith
Sent: Friday, October 12, 2007 4:57 PM
To: Discussion about mythtv
Subject: Re: [mythtv-users] Still no AC3 passthrough...


On 10/12/07, Greg Arena <gma at gmadigitaldesign.com> wrote: 

	Darren,
	
	        I un-muted the IEC958 Output in alsamixer. Until
I did
	that, I was getting no audio at all. So that part appears
to be
	correct - once I did that, I was able to get 2-channel
audio
	working before I tried getting the pass-through to work
again. 
	        I'd appreciate it if you could tell me what
settings are
	working for you. I have a feeling I may have tried them
already.
	I'm beginning to think the problem may be somewhere else
because,
	as I said in another post, running "aplay -L" results in
a 
	segmentation fault and I did a lot of experimenting,
upgrading
	ALSA, etc.


This is not a fix all solution, but if you haven't you might want
to try ignoring the .asoundrc for now and just entering
ALSA:iec958 (or ALSA:spdif depending on your card) in myth as
your passthrough device.  If things need to be resampled this
will not work, but in my case and at least for a few other folks,
this works for most things.