[mythtv] Fw: [mythtv-users] Myth is locking soundcard and preventing fullduplex operation

James Knight foom at fuhm.net
Tue Apr 15 23:38:13 EDT 2003


On Tuesday, April 15, 2003, at 05:43  PM, Edward Wildgoose wrote:
> Nope, killed all that junk to be sure.  Literally when mythbackend is
> running, but not recording, then I can use arecord and aplay 
> simultaneously
> (gives a kind of delayed tv sound when xawtv is running).
>
> However, while arecord is running, trying to fire up xmms gives error
> messages about the device being locked.  A similar but slightly 
> different
> message appears if I try and run up xmms while mythtv is recording.
>
> I *can* then play back the recorded tv show with sound once myth has
> finished recording, but there is no sound if I try and play while myth 
> is
> still recording, so something is definitely happening during record 
> which is
> locking the sound device.

I believe myth uses OSS to record/playback, so it would be going 
through the ALSA OSS emulation layer. aplay and arecord do *not* use 
the OSS emulation layer of ALSA, they use the ALSA interface directly. 
What it sounds like you're seeing is that the ALSA OSS emulation layer 
thinks your sound card is not capable of full-duplex for some reason, 
but the direct ALSA interfaces think it is. I would try this to test my 
theory:
cat /dev/dsp > /dev/dsp

(replace /dev/dsp with the other appropriate dsp# device if necessary)
If that doesn't work (if it gives an error) then the ALSA OSS emulation 
is broken and it has nothing to do with myth. You'll either need to 
write a patch to myth to use ALSA directly (since apparently that 
works), or else somehow fix ALSA.

Also out of interest what does ls /dev/sound have in it?

James



More information about the mythtv-dev mailing list