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From: tjr@cbnewsc.att.com (thomas.j.roberts)
Newsgroups: rec.music.synth,comp.music
Subject: Re: MIDI protocol and ISDN network
Message-ID: <1990Oct5.144334.1196@cbnewsc.att.com>
Date: 5 Oct 90 14:43:34 GMT
References: <2637@ttardis.UUCP>
Organization: AT&T Bell Laboratories
Lines: 42

From article <2637@ttardis.UUCP>, by rlw@ttardis.UUCP (Ron Wilson):
> In article <2707b24b.3dd1@petunia.CalPoly.EDU>, sseidman@polyslo.CalPoly.EDU (The MIDIman) writes:
>> [...]   Sooooo, does anyone have any info on how
>>MIDI and ISDN may someday work together?  How does ISDN accomodate MIDI?
> [...]
> The MIDI standard is a 2 layer specifation: The physical transmission, and the
> data protocol itself.
> 
> As far as ISDN, OSI, TCP/IP, SNA, and other communication protocols suites are
> concerned, the MIDI data protocol is "just another application protocol" - ie,
> ISDN et al will treat the MIDI messages as data. [...]

BUT, and that is a very BIG BUT, MIDI is inherently a real-time
protocol - the time between messages is preserved to very high accuracy.
ISDN is not a real-time protocol, and will not preserve the time
between messages (buffering can occur at any node - I am assuming
packet-switched data on ISDN). ISDN can also introduce excessively
large delays (compared to typical MIDI implementations). If you consider
ISDN circuit-switched data, then ISDN is essentially acting only as a
physical layer, which could preserve the real-time nature of MIDI data,
except for overall delay (which is inherent in the typically wide-area
implementation of ISDN - a typical ISDN connection between two phones in
the same room is routed to a telephone office several miles away).
Typical delays for packet-switched ISDN data are 100 milliseconds
(one way, both terminals in the same room), much too large for an
integrated MIDI performance.

Also, ISDN is a NETWORK ACCESS protocol only, MIDI is essentially
a network protocol. What this means in practice is that the performance
of MIDI systems is pretty much the same (from a network standpoint).
The performance of different ISDN systems varies a lot.

ISDN is intended for wide-area networking; its typical use is from
building to building, to across the country. MIDI is intended for
localized performance. I have trouble imagining a nationwide MIDI
performance.

As a user of both ISDN and MIDI, I seriously doubt that anyone will
ever implement a network interface product to connect them.

Tom Roberts
att!ihlpl!tjrob