[LAU] Motu M64 Madi interface (not) class compliant?

Peter P. peterparker at fastmail.com
Fri Mar 12 22:25:48 CET 2021

* Anders Hellquist <lau at hellquist.net> [2021-03-12 21:40]:
> I have three Motu devices and Motu have changed their CC USB stance to only
> allow 24 + 24 streams over usb.
> This happened a long time ago with a firmware update for Ultralite AVB
> which did support 64+64 when running 44k1 or 48k.
> Newer models of Ultralite does not support downgrading to older firmware
> that supports more than 32 streams.
> The same seems be the case with my Motu 24ai and might be true even if
> running native driver for Windows or MacOS (have not tried) Motu 24ai
> supports 72 channels + avb streams so I'm total. Close to 170 channels so
> the limited USB support really cripple the usage.
> I have repeatedly been I contact with Motu support and the state they love
> Linux and promises things will improve but so far there has been no proof
> to back it up.

In my perception RME cards were the most decent cards under Linux until
they started their fireface series. Until then pci, pcie, cardbus and
expresscards allowed linux use of everything up to their madiface (yes,
with full 64 I/O). When it became clear that this happy situation is
fading away, especially on laptops without expresscards slots, Motu
seemed like a good alternative for a short time, until these
disadvantages were introduced that Anders and many others mentioned. For
now I feel that the best way is to go for USB class compliant interfaces
that have no on board mixer of FX. Speaking of Madi, this also means
being limited to 24 or 48 channels I/O depending on if it is an RME,
Digico, or Motu device).
I discovered that Adrian Knoth is working on an alsa driver for the
RME MADI FX at https://github.com/adiknoth/madifx

Now what is the current state of AVB interfaces for Linux. Does anyone know how
well this format and its devices are supported in 2021?

cheersz, P

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