[mythtv-users] Sound problem - suspect alsa issue

[Bob Sully]

Hi all -

This is a problem I've been having for a while; it's been an annoyance but
happened infrequently enough before that I just dealt with it by rebooting
the Myth box.  However, it's happening more often now and seems to be
somewhat random.  Before, it would happen most often when switching back
from Mythmusic to playing recordings or video files; now it seems to
happen even if I don't play music.

I am feeding my AV receiver (Sony DG-STR1200) from the Myth box via S/PDIF
(coaxial).  Mobo is an ASUS P5K Deluxe; the sound chipset uses the
hda-intel driver.  OS is currently updated Ubuntu 10.04, running latest
JYA binaries.

The problem is that occasionally the S/PDIF output gets "locked" in analog
mode.  Using the "input mode" on the receiver's remote (which switches
from "analog only" mode to autodetect) doesn't fix it, for in autodetect
mode all it seems to be seeing is an analog signal.

If I view a video file with, say, VLC, pulseaudio's volume control shows
that there is activity on the IEC958 output - but there's no sound.  So, I
assume it's an ALSA problem.


I can't fix it with alsamixer.

Trying to run "iecset audio 0" gives me:

[mythtv at vader: ~]$ iecset audio 0
snd_ctl_elem_write: Operation not permitted

(I get this whether or not I do it as root)

iecset -X gives me:
AES0=0x04,AES1=0x82,AES2=0x00,AES3=0x02

I tried this too:
[mythtv at vader: ~]$ sudo iecset pro off audio off
snd_ctl_elem_write: Operation not permitted

The only way to fix this appears to be to reboot the box.  PITA!
Turning the receiver on and off doesn't fix it, as it's only seeing an
analog-mode feed from the computer.

Anyone else seeing this?
Is there an easier way to deal with it?


Also, I've had to go back to NOT upmixing Mythmusic to 5.1; I only get
sound from the surround speakers occasionally, and when it does come on,
it's distorted and annoying (and only comes on for a second).  It sounds
OK in 2.0.


Thanks for any help!
-- 
________________________________________
Bob Sully - Simi Valley, California, USA
http://www.malibyte.net
http://www.malibyte.com