Hi all gurus
I am struggling to get sound correct in MythTv, I am using
a P7131 Asus Tv card with analogue rf input. The video is
great and the v4l driver works very well. When it comes to
sound it is another story. Currently I am running Suse
10.1, my sound system works well when playing audio s
through the bus. So I know that my audio sub system is
working.
In Mythtv I could only get the sound to work when I use a
short audio jumper cable from the TV card to the onboard
sound card CD input, could only get sound by using the
"v4lctl -c /dev/video0 volume mute off" command, but the
sound and video is not synchronized
I decided to try and get it to work without the jumper
cable and this is how I proceeded.
Using Xawtv the only way I could get it to work is to issue
the following commands. 1. modprobe ?
this creates a /dev/dsp1 device. Using aplay /dev/dsp1 I
managed to get sound out of xawtv but still not
synchronized.
When I now run MythTV and select /dev/dsp1 as audio device
it tells me it t find /dev/dsp1 device although it is
there, I suspect that something else is locking it. When I
run aplay /dev/dsp1 I can noise coming through and as soon
as I start MythTV the channel sound comes through but not
synchronized. This is where I am really stuck now and any
inputs from you will be much appreciated. Thanks, Marcus
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*em*&cid=113&u=8&tid=1138

Am Dienstag, den 12.09.2006, 13:51 +0200 schrieb Marcus Human:
Hi all gurus

I am struggling to get sound correct in MythTv, I am using
a P7131 Asus Tv card with analogue rf input. The video is
great and the v4l driver works very well. When it comes to
sound it is another story. Currently I am running Suse
10.1, my sound system works well when playing audio s
through the bus. So I know that my audio sub system is
working.
In Mythtv I could only get the sound to work when I use a
short audio jumper cable from the TV card to the onboard
sound card CD input, could only get sound by using the
"v4lctl -c /dev/video0 volume mute off" command, but the
sound and video is not synchronized
I decided to try and get it to work without the jumper
cable and this is how I proceeded.
Using Xawtv the only way I could get it to work is to issue
the following commands. 1. modprobe ?
this creates a /dev/dsp1 device. Using aplay /dev/dsp1 I
managed to get sound out of xawtv but still not
synchronized.
When I now run MythTV and select /dev/dsp1 as audio device
it tells me it t find /dev/dsp1 device although it is
there, I suspect that something else is locking it. When I
run aplay /dev/dsp1 I can noise coming through and as soon
as I start MythTV the channel sound comes through but not
synchronized. This is where I am really stuck now and any
inputs from you will be much appreciated. Thanks, Marcus

Hi Marcus,

no guru here, but Ricardo's saa7134-alsa mute switch works a treat on
mythtv. It is in the master repo meanwhile and that should compile on
SuSE currently, IIRC.

If no app uses the tuner it goes standby and audio should be muted, but
I confirm sometimes it emitts noise instead. The card seems not to play
such nice with all kind of stuff walking lots of ioctls including v4l1
ones.
You could experiment with using v4l2ucp.sf.net to keep it unmuted.

Most important to get no sound drift is to have a sample rate of 32000Hz
with saa7134-alsa. Enable debug for saa7134-alsa to see if you still get
buffer over/under-runs. If it is not a software or performance problem,
there are also means to compensate for a audio crystal on the card which
could be slightly off. (modinfo saa7134)
We don't have an internal sample-rate converter and also not all audio
drivers play well if they do conversion or simply don't support 32kHz.

Cheers,
Hermann