Seeking CoreMIDI-users input on an IETF effort ...
Seeking CoreMIDI-users input on an IETF effort ...
- Subject: Seeking CoreMIDI-users input on an IETF effort ...
- From: John Lazzaro <email@hidden>
- Date: Sat, 29 Jun 2002 19:28:37 -0700
Hi everyone,
A mildly off-topic post here, I'm part of an
IETF effort (called MWPP) to add MIDI support to the
Real Time Protocol (a standard for real-time media
over Internet Protocol), and we want to check that our
proposal will work both for people writing CoreMIDI
drivers to display MWPP MIDI data as CoreMIDI sources/sinks,
and for people interfacing MWPP streams to MIDI hardware
accessed via the CoreMIDI API.
Coreaudio-api seemed to be the place to ask for
input ... I've read over the CoreMIDI docs, but I haven't
written any CoreMIDI code yet, and so I thought I should
check with people who have.
Basically, in MWPP, timestamped MIDI commands are
placed into RTP packets and sent over a network. However,
a single method for timestamping isn't mandated by MWPP.
Instead, as part of session setup, the RTP sender lets
the receivers know the method of timestamping, using a
flexible set of configuration parameters.
This way, if the OS API to a MIDI In jack forces
a particular timestamp method, the sender doesn't need
to "convert to IETF timestamps". Instead, the receiver
adapts to the timestamps -- good, because the receiver
knows what its going to do with the MIDI.
The method for describing the timestamp semantics
is described in Appendix C.2 (pages 57-60) of this memo:
http://www.cs.berkeley.edu/~lazzaro/sa/pubs/txt/current-mwpp.txt
It will probably be necessary to read Sections
1, 2, and 3 of the document before skipping to Appendix C.2
to get oriented, but it won't be necessary to read the whole
70 page draft to understand what is going on (I hope :-).
Comments may be sent directly to me, or posted on
the IETF AVT Working Group list -- you need to join the list
to post, send mail to email@hidden to join. It's probably
not a good idea to send comments to coreaudio-api, since its
an off-topic discussion ... thanks in advance!
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John Lazzaro -- Research Specialist -- CS Division -- EECS -- UC Berkeley
lazzaro [at] cs [dot] berkeley [dot] edu www.cs.berkeley.edu/~lazzaro
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