[mythtv] HOWTO: audio missing after SuSE 9.0 -> 9.1 update.

[Martin Moeller]

This is rather puzzling for me.

I think I've tried all the troubleshooting tips in the documentation and
on the list, so here goes:

After I had updated the system the audio was initially (before even
using mythtv) full of static and underneath I could hear some audio.
If I shut down alsasound this went away. Apparently the OSS driver
worked okay, only shortly after, logging out of root and in as myself
the static returned and the ALSA modules were loaded again. I tried
instructing the kernel to prefer the OSS module by setting this as the
alias in /etc/modprobe.d/sound and disabling alsasound from running. On
the next reboot sound was okay, but apparently it is still the ALSA
modules that are running?! Fine with me so far -- didn't really wan't to
be stuck with the OSS drivers. 

Sound output from tvtime and xawtv is fine.

If i mute 'video' on my soundcard, audio stops. So far so good.
This is a SAA7134 card, BTW.

Running mythbackend/frontend and watching live TV or recording a show
gives me nice moving pictures but no sound. Tried both 32000, 44100 and
48000 Hz. The only thing that thus far have given me sound is having
xawtv running in the background and then going to live TV. If I change
channels I get a lot of static in stead of audio for the new channel. If
I exit xawtv the sound disappears. As I was unaware at first that I had
xawtv running I initially thought the change came from increasing the
capture rate from 32000 to 44100 but alas, no such luck....

I can capture audio when running tvtime or xawtv with the aplay /dev/dsp
trick and record it with e.g. arecord -f cd -d 30 /tmp/audio.wav

I have tried a couple of time to capture sound from the extra DSP device
the SAA7134 can provide but that has always given me no audio, even
before the update so....

The 'no audio' thing happen(ed/s) with both the version I used in SuSE
9.0 and CVS from today/yesterday. I probably should note that I am now
on a 2.6.4 kernel where before it was a 2.4.x kernel so both
sounddrivers and grabber modules are new compared to before...

Still to try:
v4lctl volume mute off

Hmm. That actually worked! Have something changed lately that broke the
fix that was previously made for this exact situation, I wonder...?

Output from v4lctl list (while running tvtime):
martin at monsterpc:~> v4lctl list
attribute  | type   | current | default | comment
-----------+--------+---------+---------+-------------------------------------
norm       | choice | PAL     | PAL     | PAL NTSC SECAM PAL-M PAL-Nc
input      | choice | Televis | Televis | Television Composite1 S-Video
audio mode | choice | stereo  | mono    | mono stereo lang1 lang2
bright     | int    |     128 |     128 | range is 0 => 255
contrast   | int    |      64 |      68 | range is 0 => 127
color      | int    |      64 |      64 | range is 0 => 127
hue        | int    |       0 |       0 | range is -128 => 127
volume     | int    |      12 |       0 | range is -15 => 15
mute       | bool   | off     | off     |
vertical f | bool   | off     | off     |
Invert     | bool   | off     | off     |
y offset o | int    |       0 |       0 | range is 0 => 128
y offset e | int    |       0 |       0 | range is 0 => 128

mythtv, before v4lctl volume mute off:

martin at monsterpc:/tmp> v4lctl list
attribute  | type   | current | default | comment
-----------+--------+---------+---------+-------------------------------------
norm       | choice | PAL     | PAL     | PAL NTSC SECAM PAL-M PAL-Nc
input      | choice | Televis | Televis | Television Composite1 S-Video
audio mode | choice | stereo  | mono    | mono stereo lang1 lang2
bright     | int    |     127 |     128 | range is 0 => 255
contrast   | int    |      63 |      68 | range is 0 => 127
color      | int    |      63 |      64 | range is 0 => 127
hue        | int    |       0 |       0 | range is -128 => 127
volume     | int    |      12 |       0 | range is -15 => 15
mute       | bool   | on      | off     |
vertical f | bool   | off     | off     |
Invert     | bool   | off     | off     |
y offset o | int    |       0 |       0 | range is 0 => 128
y offset e | int    |       0 |       0 | range is 0 => 128

On the up side it *looks* like I now have stereo sound. Yippie!
Just need to find a decent recording level. It seems I get distorted
sound even at less than 50% on capture?!

Well, this message turned out to be more informational than asking for
help after all. Who'da thunk it? Hope someone else can troubleshoot
similar problems with this as a guide.