[linux-audio-dev] Re: MIDI over WiFi
lazzaro at eecs.berkeley.edu
Sat Mar 31 17:27:07 UTC 2007
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
> transmitter/recaiver dongle-thingie and fast forward to the wireless
> capabilities already built in to most of modern portable devices sold
> today? Hey, even the OLPC aimed at third world children have this
> capability ...
If you access to two OS X machines for a few minutes, run the
Network MIDI Driver over Airport (Network MIDI Driver described here:
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:
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lose packets -- although my info on the product might be out of date):
> 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:
make the point well of how limiting the battery life can be for
a MIDI wireless controller right now.
lazzaro [at] cs [dot] berkeley [dot] edu
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