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:
http://www.soundonsound.com/sos/jul05/articles/tiger.h
tm#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lose packets -- although my info on the product might be out
of date):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.ber
keley.edu/~lazzaro
lazzaro [at] cs [dot] berkeley [dot] edu
---
|
