Re: [Alsa-user] MIDI events of custom USB device not appearing in aseqdump

[Clemens L. <cla...@go...>]

Kevin Cuzner wrote:
> My device presents a USB Midistreaming interface with the following
> characteristics:
> - A single embedded MIDI IN jack with ID 1
> - A single embedded MIDI OUT jack with ID 2
> - A single element with ID 3
>   - The embedded MIDI IN jack is attached to the single input pin.
>   - The embeeded MIDI OUT jack is attached to the single output pin.

Please show the output of "lsusb -v" for your device.

> My device is the "Midi-Fader". When I run "aseqdump -p 28:0" I see
> nothing appear.

Try amidi, which will show even invalid bytes.

> However, Wireshark shows that my device is sending USB-MIDI Event
> Packets (just Bulk IN packets with a length of 4) with the following
> binary content:
>
> 2b 07 31 00

07 is not a valid MIDI status byte.  The first byte of the USB-MIDI
Event Packet is not MIDI; the remaining bytes must be valid MIDI.  See
the second example in table 4-2.

> - Cable 2

Section 4 of the USB MIDI specification says:
| The Cable Number (CN) is a value ranging from 0x0 to 0xF indicating
| the number assignment of the Embedded MIDI Jack associated with the
| endpoint that is transferring the data.

That "number assignment" refers to the following algorithm (which
everybody pretends is obvious): the cable numbers of an endpoint are
from zero to one less than bNumEmbMIDIJack.

> I have a Yamaha MOXF8, but it appears to enumerate as a custom device
> and does not use the standard USB-MIDI interface.

Yamaha devices use the standard protocol, and even have a list of
standard-looking jack descriptors; they just claim to be vendor-specific
devices in order to prevent being used by the built-in Windows driver.


Regards,
Clemens