On Wed, 3 May 2006, Greg Troxel wrote:

> Joanne has written a proposal to modify ugen(4) to get good
> performance for the USRP.  We'd like feedback about the technical
> approach, both on its own and about including the results in NetBSD.
> (Once we have it working, I'd like to commit the changes to -current.)
>
> http://acert.ir.bbn.com/downloads/adroit/NetBSD-USB-continuous.pdf

With regards, to using isochronous transfers, one of your sticky points is
no support for writing from userland..  There is code in pr/25960 that
would enable this for ugen.

In your "Implementation Approaches", I see no mention of mmap() and
circular buffers, as used in audio(4)/audio(9). I dont know how well this
could fit with libusb, but did you consider that method?

iain