[LAD] A question for USB/MIDI experts

Fons Adriaensen fons at linuxaudio.org
Fri Apr 8 20:26:20 UTC 2016

On Fri, Apr 08, 2016 at 10:13:27PM +0200, Philippe Wicker wrote:
> What you see seems to be the MIDI encoding used by a USB device.
> Every “simple” MIDI event (that is less that 3 bytes) are encoded
> as a 4 bytes word. The 1st byte (MSB) is - if I remember correctly
> - the concatenation of the MIDI port and a USB specific code for the
> event. The 3 remaining bytes contains the MIDI event as it is encoded
> on a standard serial MIDI line.

That makes perfect sense. 

OTOH I also have some other devices for which the USB bytes are
exactly the same as the MIDI bytes - no extra ones. 

Is it the 

      bInterfaceClass         1 Audio
      bInterfaceSubClass      3 MIDI Streaming

that would imply the format you describe ?

I will also need to send some sysexes, and would prefer to use
this device directly as a USB one without going via any MIDI
layer - the application has nothing at all to do with audio
or music. Is there any documentation on what those extra bytes
are supposed to be ?

Many thanks !



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It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

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