On 4/18/21 12:09 AM, Peter P. wrote:
* Paul Davis <paul@xxxxxxxxxxxxxxxxxxxxx> [2021-04-18 03:43]:
On Sat, Apr 17, 2021 at 4:22 PM Peter P. <peterparker@xxxxxxxxxxxx> wrote:
* Peter P. <peterparker@xxxxxxxxxxxx> [2021-03-12 18:43]:
Hi list,
can report that the Motu M64 Madi interface does work with a limited
channel count of 24 for input and another 24 for output (instead of 64
each). So if you are coming across a venue or employer that already has
one, you are good to go. Sample rate needs to be set on the device
before starting jack. Of course, buying the card for oneself for so much
money getting only one third of the channels seems useless linux users
IMHO.
I can add now that the card does not work reliably in class compliant
mode with external sync clocks. It will randomly switch back and forth
output channels in banks of eight, cause clicks and distortion and
aliasing artifacts.
The bank switching is a known problem with other MOTU USB devices, and has
been "solved" by using specific firmware releases (e.g. for the MOTU
Ultralite AVB) which may not be available anymore or for your specific
device.
>
Thanks Paul, that is good to know! Does anyone have more info on this
back switching and associated firmware updates?
(the old firmware versions are very old - they used to allow up to 64
channels in class compliant mode - and do not run in the newest hardware
that you can buy today)
There is a VERY long thread about this here:
https://linuxmusicians.com/viewtopic.php?f=6&t=18046&sid=3586a531a296e4134cd4c7418f429395
A lot of information - I was just looking at new pages at the end since
last time I looked, and there is a way to get a telnet root login into
the boxes, ha ha - running linux internally of course (I expect this
will be gone in the next firmware release :-)
Anyway - not really a resolution to the issue in the thread, but lots of
ideas to try.
I am running a couple of motu interfaces using a patched kernel that
enables the use of the alternate usb (proprietary) endpoints and that
works mostly fine (64 channels over usb with current firmware, 16A & 8M
tested with this). But the patch does not patch over current kernels and
a LOT has changed in the audio usb driver, I still have to figure out
where to do things now. Sigh.
-- Fernando
I do not believe that the aliasing is caused by bank switching, but by
(possibly) an ALSA driver bug. It generally goes away within a few minutes
or on device restart.
But wouldn't that driver bug affect all class compliant interfaces then?
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