Re: [xwax-devel] jack and alsa audio plus dicer.

[Mark H. <ma...@xw...>]

On Mon, 22 Apr 2013, Ewan Colsell wrote:

> my soundcard is a mixvibes umix44 which needs a .asoundrc to work with 
> xwax using alsa.
> 
> the only problem is that the .asoundrc has a massive buffer
> 
> pcm.umix44_playback {
> 	type dmix
> 	ipc_key 1646
> 	slave {
> 		pcm "hw:Device"
> 		period_size 0
> 		buffer_size 65536
> 		rate 44100
> 		channels 4
> 	}
> 
> i have tried using a smaller buffer size but it won't work.
> 
> 
> since jack does not have this problem (i get 2.9ms latency in jack)
> i would prefer to use jack.

Interesting, it cound be a particular combination of parameters that's not 
working.

Look at files in /proc/asound when JACK is running (or even the JACK 
config) may tell you an appropriate combination of period_size, 
buffer_size + rate that you can use.

If JACK works it's definitlely going to be possible to get it working.
 
> unfortunatly xwax's dicer support only works when alsa is enabled
> i have tried adding a 3rd deck using the alsa 'Dummy' driver but i get the
> following error on startup:
[...]
> Initialising deck 0 (deck1)...
> JACK: 44100Hz
> Initialising deck 1 (deck2)...
> Initialising deck 2 (hw:Dummy)...
[...]
> Launching realtime thread to handle devices...
> xwax: device.c:106: device_handle: Assertion `dv->ops->handle != ((void
> *)0)' failed.

This is really interesting. I've never seen this before. This should never 
happen (hence it's an assert)

You could help me by reproducing the problem using only the 'dummy' deck, 
then sending over the asoundrc and command-line args?

Possibly this indicates a wider bug, I'm not sure.

Nevertheless, a dummy device is going to be hard to get right in a 
realtime environment. Instead I suggest...

[...]
> i there was a patch to enable the dicer working with jack a while back but
> it never worked for me.

I forgot to incorporate this patch, silly me. I've put it into the Git 
master now, so if you're able to test that? Then you should be able to use 
JACK audio with the ALSA midi.

When you say the patch didn't work, I don't know if you mean you couldn't 
apply it, or it didn't do what I said it did.

> any way i can help?

If you are able, send more info on the crash above, and try the Git 
master. Thank you!

-- 
Mark