From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Mack <zonque@gmail.com>
Subject: Re: How to add a new MIDI device to the usbaudio driver
Date: Thu, 25 Aug 2011 14:38:27 +0200
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To: Kristian Amlie <kristian@amlie.name>
Cc: alsa-devel@alsa-project.org, Clemens Ladisch <clemens@ladisch.de>
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On Thu, Aug 25, 2011 at 1:28 PM, Kristian Amlie <kristian@amlie.name> wrote:
> One caveat I have discovered with the patch: If you keep the instrument
> plugged in, but reload the driver, then the driver gets out of sync with
> the MIDI messages and won't report any. This seems to be because, in the
> stream, the message type is cached and subsequent messages do not report
> what type of message they are unless they are switching to a new type
> (going from control message to note message, for example). You can reset
> the stream by manually generating MIDI messages of different types (turn
> the volume knob while pressing a few notes), or eventually the
> instrument will reset itself and send the type anyway. So it's not
> critical, but would be nice to fix. I'm not sure how to solve it though...

What you're seeing here is a general problem of the MIDI protocol that
cannot be fixed. If a receiver misses the running state update, it
can't do anything but wait for the next one.


Daniel