[linux-audio-user] USB, what's the story? (was: Firewire, what's the story?)

Jack O'Quin joq at io.com
Tue Dec 9 14:02:49 EST 2003

Patrick Shirkey <pshirkey at boosthardware.com> writes:

> Ryan wrote:

> > Is this fixed-time vs. fixed-size usb issue addressed in the 2.6
> > kernel (or is it alsa or is it something else)?  Just curious
> > where the "heart" of the issue is and what kind of time line we
> > are looking at.

There are probably several levels of problems.  The USB bus
architecture is misdesigned for serious audio use.  ALSA seems to have
trouble with some of these devices.  In may cases, the hardware may be
at fault.  I am not aware of kernel issues, but there probably are
some, perhaps when hot-plugging these devices.  

Plus, JACK is designed to work with fixed-sized buffers, which
interacts badly with USB's isochronous behavior.

> Our best hope is someone wise and knowledgable writing a patch for
> JACK at this stage. Unfortunately noone can access the mantis database
> to add a feature request so it's probably being put off.

Mantis is working for me ATM.

While it's not being ignored, this *is* a hard problem.  We want to
develop a workaround in JACK.  Bug:000017 is already open and seems to
address this issue...


No promises have been made about how soon this will happen.

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