Re: [Jack-Devel] jackd2 does not start with Terratec 6fire USB

Le 29 oct. 2011 à 16:22, richard lucassen a écrit :

> On Sat, 29 Oct 2011 10:07:39 -0400
> Paul Davis <[hidden]> wrote:
> 
>> On Sat, Oct 29, 2011 at 9:50 AM, richard lucassen
>> <[hidden]> wrote:
>> 
>>> period_size: 600
>>> buffer_size: 22050
>> 
>> this is pretty seriously braindead. that means that the overall buffer
>> in use is 36.75 periods long. every 37th period will be split across
>> the beginning and end of the buffer. ALSA can handle this kind of
>> nonsense, and thus JACK can too, except that its not going to ever ask
>> for an equivalent h/w configuration because it will never ask for a
>> buffer size that is anything other than the -n value multiplied by the
>> -p value, and both of them are integral.
>> 
>> its also fairly braindead in another way too: huge i/o latency (half a
>> second), yet with no actual decrease in CPU load since the device
>> keeps waking up the CPU every 600 samples. all the downsides of large
>> latency with none of the benefits ...
>> 
>> and in another way: 600 samples isn't a divisor of the USB transfer
>> frame size, which will cause additional issues with load etc.
>> 
>> you should definitely find somebody else who has used this with JACK
>> and/or talk to the author of the driver of this card (except that i
>> would have guessed that it was a generic USB class 1 audio driver ...
>> so ... ?)
> 
> So, I will forward your answer to the author of the driver. It's all
> here:
> 
> http://sourceforge.net/projects/sixfireusb/
> 
> But OTOH: cpu load, that's another story, but could this issue be the
> cause of jackd not starting?
> 
> R.
> 

Error message :

===========================
ALSA: cannot set period size to 1024 frames for capture
ALSA: cannot configure capture channel
===========================

That's pretty clear no?

Stéphane 

1319898527.10129_0.ltw:2,a <8E497CE9-5D59-465C-9022-6FDAA1F60730 at grame dot fr>