Subject: [AVT] updated MIDI packetization I-D submitted

From: John Lazzaro <[email-masked]>
Date: Tue, 2 Oct 2001 12:26:19 -0700

Hi everyone,

	We've finished rewriting:

---

  MWPP: A resilient MIDI RTP packetization for network musical performance

                <draft-lazzaro-avt-mwpp-midi-nmp-00.txt>

                                Abstract

     This memo describes the MIDI Wire Protocol Packetization (MWPP).
     MWPP is a resilient RTP packetization for the MIDI wire protocol;
     it is specialized for low-latency applications such as network
     musical performance. MWPP defines a multicast-compatible recovery
     system for gracefully handling lost and late packets during the
     performance.

     In a network musical performance system, incoming MWPP streams
     control audio synthesis software running on each network host. This
     software might use the MPEG 4 Structured Audio standard as a
     normative framework for audio synthesis. To support MPEG 4
     Structured Audio in an interoperable fashion, this memo describes
     how to transport MWPP via the generic MPEG 4 RTP packetization.

---

and sent it off to [email-masked], hopefully an announcement
will happen in the next few days.  Until the official announcement,
you can pick up the new I-D using this URL:

http://www.cs.berkeley.edu/~lazzaro/files/ietf/draft-lazzaro-avt-mwpp-midi-nmp-00.txt

Note the I-D number is still -00 because the I-D name needed to be
changed. The memo has changed in several major ways, in response to WG
feedback:

[1] MWPP is now, explicitly, a MIDI RTP packetization for low-latency
applications such as network musical performance; it is no longer
defined to be an MPEG packetization. The change reflects the goal of
supporting all low-latency MIDI softsynth applications, not just MPEG
4 Structured Audio applications.

[2] The relationship between the memo and MPEG 4 is two-fold:

  -- The memo normatively includes the MPEG 4 Structured Audio document,
     because MWPP borrows the semantics of MIDI control of a software
     synthesizer from the document. Since these semantics are sound,
     and are simple to apply to other, non-MPEG-4 software applications,
     it is easier to include these semantics normatively from an MPEG
     document, than to regurgitate them in an IETF document.

  -- Because the memo normatively includes the MPEG 4 Structured Audio
     document, the recovery semantics of MWPP are a good match for 
     Structured Audio systems. However, for maximum interoperability,
     these Structured Audio applications should use "RFC-generic", not
     the RTP packetization MWPP uses. To solve this problem, we've added
     two sections to the I-D: Section 9, which describes how to use 
     MWPP with RFC-generic, and Section 12, which describes the SDP
     to configure RFC-generic for use with MWPP. These sections draw
     heavily from the recent draft-ietf-avt-mpeg4-simple-00.txt I-D.

WG members who read the earlier I-D only need to read the abstract,
Section 1 (Introduction), and Sections 9 and 12 ("RFC-generic"), the
other sections and appendices of the I-D are virtually unchanged from
the earlier version.

The plan from our end is to monitor the WG response, to see if the
issues from the first draft are satisfied; once that wave passes, we
plan to post pointers to the I-D to a few mailing lists where
mainstream MIDI applications folks hang out, and encourage them to
read the I-D, and join the AVT mailing list if they want to discuss
MWPP open issues. This seems to be a way to solicit feedback from
related communities, in a way that makes the WG aware of the open
issues ...

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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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Audio/Video Transport Working Group
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