[linux-audio-dev] Re: MIDI over WiFi

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To: <linux-audio-dev@...>
Cc: lazzaro <lazzaro@...>
Date: Saturday, March 31, 2007 - 5:34 pm

On Mar 31, 2007, at 5:26 AM, Jens M Andreasen wrote:

> What I wonder is; wouldn't it be possible to bypass this USB radio

If you access to two OS X machines for a few minutes, run the
Network MIDI Driver over Airport (Network MIDI Driver described here:

http://www.soundonsound.com/sos/jul05/articles/tiger.htm#3

You'll see it works OK, even with the 1-2% packet loss that the IP
layer sees on a typical WiFi network. Apple's implementation uses
IETF RFC 4695 (a.k.a. RTP MIDI) as the transport layer, which
includes a resiliency system (the recovery journal) for handling
an arbitrary number of lost packets with only transient artifacts.

More on RTP MIDI here:

http://www.cs.berkeley.edu/~lazzaro/rtpmidi/index.html

Note that there are actually third-party products now compatible
with Apple's protocol, although these products are for wired networks.
And, last time I checked didn't implement the recovery journal
part of the RTP MIDI (and so can't be trusted over switches that
lose packets -- although my info on the product might be out of date):

http://www.kiss-box.com/products.pdf

> It kind of puzzles me that this is not happening already ...

I haven't looked into the issue in detail, but for my own use wireless
only makes sense if I don't have to be constantly worrying about
the battery life of the device. At the moment, what I see in
the state of the art in portable WiFi chips -- the chip in the Sony
PSP and the chip in the Microsoft Zune -- is not too encouraging
in this regard. But hopefully in a few generations of chip designs
this will get better. This review:

http://emusician.com/midi/emusic_maudio_midair/

make the point well of how limiting the battery life can be for
a MIDI wireless controller right now.

---
John Lazzaro
http://www.cs.berkeley.edu/~lazzaro
lazzaro [at] cs [dot] berkeley [dot] edu
---

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Messages in current thread:
[linux-audio-dev] Re: MIDI over WiFi, lazzaro, (Sat Mar 31, 5:34 pm)
Re: [linux-audio-dev] Re: MIDI over WiFi, carmen, (Sat Mar 31, 6:01 pm)