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

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 ... ?)

--p

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