Subject: Re: [linux-audio-dev] Linux-friendly MIDI interface boxes?
From: Eli Brandt (eli_AT_v.gp.cs.cmu.edu)
Date: ke loka 13 1999 - 21:03:17 EDT
Paul Barton-Davis wrote:
> The USB stuff should work at some point, but the last i heard, the
> kernel/driver USB group were still trying to get hold of some Opcode
> USB devices to test.
Not Linux-related yet, but has anybody done timing tests on USB MIDI
interfaces? The Roland/Microsoft proposal for MIDI on USB (dunno if
Opcode uses it; I know MOTU doesn't) worries me. It sends MIDI as
`bulk transport'.
Each ~1500-byte USB frame has slots allocated for isochronous
(guaranteed-bandwidth) connections, plus some room for control data.
What's left over is handed out with no particular arbitration to
people wanting bulk transport. Sending MIDI this way seems risky if
there's other activity on the bus. I'm curious whether people
actually see the interference I expect.
--
Eli Brandt | eli+@cs.cmu.edu | http://www.cs.cmu.edu/~eli/
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