[Jack-Devel] Why can I only select 512 samples?

[Chris Caudle]

On Wed, February 21, 2018 10:53 pm, lowkeyoutlaw wrote:
> Thanks for the reply. I have the Behringer USB Guitar Link.

OK, your first message was really confusing.  You mentioned MPC software,
the only MPC I am familiar with is the Akai MPC samplers.  I don't see how
an Akai sampler could be related to setting up a USB interface, so how an
MPC device relates to settings of your USB driver is not clear.

> Without Jack, in any audio app, I can choose any setting I want, i.e.
> 128, 256, 512, 1024 samples, etc..

OK, so that establishes that the hardware supports those settings.

First, is this on Windows, Mac OS, or Linux?

I see on the Behringer page that they offer an ASIO driver for that
interface.  Are you using native USB or ASIO on Windows?

> It's only when using Jack that I can't change it in the MPC software.

How does the MPC software relate to the USB interface?

Are you talking about this software that I found described on the Akai web
page:
"Featuring 128-track sequencing capability and up to eight pad banks--more
than any other MPC ever—the included MPC Software delivers a massive 7GB+
sound library, including all the sounds of the classic MPC3000 and
including 2 MPC Expansions."

So this is basically another audio production software package, kind of
like Ableton Live or something like that?  It lets you arrange loops,
beats, etc. for song composition?

So basically the MPC USB controller works together with the MPC software
running on your computer to provide a variation of  the things the old all
in one box MPC devices used to do.  Is that close to correct?

> I can change it in Mixbus, but it garbles the audio.

All applications must run with the same buffer settings when using jackd. 
There is a way that the jack server can inform software that the settings
have changed, but only software which uses jack natively, without any kind
of translation software, will work properly when that happens.  For
practical purposes unless you are running Linux that means Mixbus, Ardour,
QTractor, and...that's all I can think of actually. Maybe Reaper, but I'm
not sure about that.

Anyway, the point being that for nearly anything else, you can't change
the settings once you start up the software, so first start jackd with the
settings you want to use, then start all the other applications.  Once the
applications are running don't change the settings.


-- 
Chris  Caudle