The problems we had with glitching audio and possibly also channel hopping
seems to affect Apple and windows users too to a degree according to
thrrads at motunation.
That means there are likely bugs in the firmware that are causing
this issue and the Linux problem might not even be a Linux issue.
Since there is now a better way to debug this using the newly discovered
root access, there might be workarounds or other nice things in the pipe.
On Mon, Apr 19, 2021, 20:00 Fernando Lopez-Lezcano <nando(a)ccrma.stanford.edu>
On 4/18/21 12:09 AM, Peter P. wrote:
* Paul Davis <paul(a)linuxaudiosystems.com>
> On Sat, Apr 17, 2021 at 4:22 PM Peter P. <peterparker(a)fastmail.com>
>> * Peter P. <peterparker(a)fastmail.com> [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
>>> 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
>>> money getting only one third of the
channels seems useless linux users
>> 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
"solved" by using specific firmware releases (e.g. for the MOTU
Ultralite AVB) which may not be available anymore or for your specific
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:
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.
> 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
But wouldn't that driver bug affect all class compliant
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