Subject: Re: [AVT] MWPP: The Atlanta Status Report

From: John Lazzaro <[email-masked]>
Date: Tue, 19 Nov 2002 13:56:24 -0800

> Colin Perkins <[email-masked]> writes:
>
> I'm not aware of any work on using the Internet multimedia protocols
> without IP, and it seems likely that they would need significant work
> to adapt to that environment. 

Thanks, I wanted to make sure I wasn't overlooking previous work. There
were two possible ways to position MWPP for low-cost LAN applications:

  [1] Get rid of the IP layer, so that MWPP+RTP could be compared
      directly against alternatives that run directly to Ethernet
      (such as http://www.dmidi.org, Phil Kerr's effort ...).

  [2] Accept IP as a prerequisite, but highlight the low overhead
      of adding IP to even inexpensive devices, and the advantages
      of running IP (better go read that "Internet is for everybody"
      RFC again :-).

It sounds like your general advice would be to forget about [1] and
focus on [2] -- and if it turns out that the MIDI over LAN space is
one where the incremental cost of the IP layer isn't justified by
the advantages of running IP, then so be it. After all, MWPP began
for WAN interactive applications (where running over Ethernet is
not an option), and then the feature-set expanded for both content
streaming and LAN-oriented uses ...

-------------------------------------------------------------------------
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
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: Ross Finlayson <[email-masked]>
Date: Tue, 19 Nov 2002 18:16:40 -0800

At 01:56 PM 11/19/02, John Lazzaro wrote:
>the advantages of running IP, then so be it.

Definitely.  An UDP/IP implementation (TCP could be omitted) is likely to 
be insignificant compared to an implementation of MWPP/RTP/RTCP, which is 
needed in any case.

In the mid-80s, I wrote a basic  implementation of TFTP/UDP/IP (for a Sun 
workstation boot PROM) that took up less than 4 kBytes.  (This ended up 
inspiring RFC 906.)

         Ross.

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From: Phil Kerr <[email-masked]>
Date: 20 Nov 2002 11:22:42 +0000

Independent of the efforts of John Lazzaro and I there are a growing
number of applications being developed to serve the domain of networked
MIDI.

A lot of this development activity is focusing on closed LAN topologies
where low latency and very low packet loss are favoring raw UDP
datagrams over RTP principally due to the implementation overheads.

DMIDI provides a clear packetisation and addressing schema which is
optimised for use within this domain.  It is very lightweight in it's
design and has a closer mapping to that of the original MIDI standard.

The cut-off point between DMIDI and MWPP is when MIDI events need to be
transmitted over the internet or unreliable networks.  This is where the
robustness of MWPP far outways any perceived implementation overheads. 
 
As the domain of internet based collaborative musical performances
matures there will be a need to bridge from the LAN to the internet and
DMIDI can support the efforts of MWPP by reducing the number of
different protocol implementations which have sprung up recently and
provide a clear path for those looking to extend their performance
reach.

John and I have discussed in the past the benefits of a transcoding
application which can act as a bridge between the two protocols.

Efforts are ongoing with other interested parties to minimise the number
of different LAN based protocols and where people are seeking to develop
applications for long-distance collaborative performances they are
directed towards MWPP.

Regards

Phil