csulliva@gandalf.UUCP (Chris Sullivan) (10/24/90)
rlw@ttardis.UUCP (Ron Wilson @ Gallifrey) wrote: > In article <2707b24b.3dd1@petunia.CalPoly.EDU>, sseidman@polyslo.CalPoly.EDU > (The MIDIman) writes: > >I am writing a paper about communications this quarter, and I have chosen > >to talk about the MIDI protocol. My teacher has refined it a bit to cover > >new topics he hasn't received before. Sooooo, does anyone have any info on > >how MIDI and ISDN may someday work together? How does ISDN accomodate MIDI? > >How closely does MIDI fit into ISDN? What needs to be done to change MIDI > >to fit ISDN? Any articles, magazines, people, or even speculation will be > >welcome. Thanks. > > Please excuse the technical language - I will try to explain as cleary as I > can. > > 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. As such, MIDI messages can > be presented as data to ANY communication protocol at the sending end, and > will be delivered to the receiver as MIDI data. > > Examples: > > 1. Two programs could send MIDI data to each other via ISDN or other data com > protocol and not even be "aware" that they are using this other protocol. > > 2. Two MIDI devices could talk to each other other an ISDN or other network > by means of MIDI<->Network servers. > > 3. A program could talk to a MIDI device in a like manner. > > In short, a communications server program (which could be running in a > computer > or in a dedicated "box" (similar to dedicated sequencers like the MC-500)) > would provide a "front end" that acts like a MIDI interface - ie: it accepts > data bytes from the program or "real" MIDI interface, and delivers data bytes > to the program or "real" MIDI interface. The communications servers are > responsible for the details of the network protocols - nothing need be done > to the MIDI data protocol. Actually, it's a bit more complicated than that. MIDI uses 30-some-odd Kbps async (or start-stop for you X.25ers) frames, which don't go naturally into the 64Kbps synchronous clear B channels provided by ISDN. The channels have synchronization information for byte-alignment associated with them. So the trick is to get the bits from the async frames into the ISDN bytes. There are various ways of doing this: - sampled async, which will not work with MIDI due to the sampling rate being too low (64k) with respect to the MIDI bit rate (30+k). Works with existing equipment at the physical layer (up to 19.2K or so). - software-based rate adaption, where the async bits are placed in specific locations in the 64k stream. See V.110. Works with existing equipment at the physical layer. - taking your MIDI data and ignoring the async aspects of the spec, and as described by Mr. Wilson, above, just using the ISDN as a clear pipe. That way you get the full advantage of 8K bytes/sec. Must be done above the physical layer. The problem is you have to have the same special equipment and software at both ends, and can't just plug existing MIDI equipment into ISDN direct. Existing ISDN physical layer terminal adapters don't work at MIDI rates, so the upshot is you will need a new kind of device, to work with existing MIDI equipment at the physical layer (or, if you have access to the MIDI data, above the physical layer). The other interesting part of ISDN is the signalling. You need to have some way of doing call set-up and tear-down, as this system is really a telephone network. So you have to pick up, dial, get talking, finish, and hang up. All this is done using the Q.931 protocol over the ISDN D channel. MIDI doesn't have any equivalent. You have to do the wiring by hand with MIDI, just like the old patch telephone boards. You will need some mapping between the different devices on a MIDI bus and their ISDN addresses (phone numbers). Your new device could do that for you too. Sounds like a kind of a MIDI bridge or router. Once you've done Q.931 and LAPD, it is easy enough to do V.120 rate adaption. This gives you some addressing capability over a single call. But the real question, Mr. MIDIman, is why? You going to hold ISDN tele- conference jam sessions or something? It's a pretty dumb way to go for MIDI unless you need long-distance, since there isn't much ISDN gear available to the consumer yet. And you will need better than 64k to carry HI-FI voice... You must not play fast and loose with standards, if you want to interwork with everybody, everywhere. You can't just bang anything you like on top of OSI transport. You can, but you can only talk to yourself that way. If you get your MIDI widget through ISO and/or CCITT, then you can interwork with others who adopt your standard. This involves international approval. It would likely also involve a rewrite of the MIDI spec. Then there's the intellectual property issue, too. Who owns MIDI? The same is true to some extent with TCP/IP, but the process is different, and very US-centric. What the TCP/IP folks would like you to do is submit MIDI to them for scrutiny, with a spec for running it on TCP or UDP. Only after the Internet moguls approve it is it recognized as a legitimate application. ISDN is a CCITT standard, and SNA is IBM's baby. See also comp.protocols, for interesting discussions. You might even start a comp.protocols.MIDI, or .ISDN, if there isn't one already. ...regards, Chris Chris Sullivan Tel: 613.723.6500 Systems Architecture Group Ext: 8253 Gandalf Data Limited Fax: 613.226.1717 130 Colonnade Rd. S. Telex: 053.4728 Nepean, Ontario chris@cannibal.gandalf.ca (134.22.80.33) Canada K2E 7M4 (Chris Sullivan @ the Hinternet)
Alvin@cup.portal.com (Alvin Henry White) (11/08/90)
I have been trying to collect all necessary data to be able to play a duet using the organ at the Morman Tabernacle and the organ at St. Peter's in Rome. I don't know if there is one at St. Peter's. I figure if both instruments have intelligent controllers, midi or some artificial intelligence, or robotics stuff, I could dial in with my yamaha portable keyboard from home, here in Silicon Valley, California, and by using local feedback to keep me on time, and by having the proper delays to sync the international circuits I should be able to get simultaneous output at my recording studios in Hollywood. Any help on technical suggestions or procedural application requirements are welcome. When I was on my was to the White House Conference on Libraries and Information Services in Washington, D.C. in 1979, my Greyhound Ameripass had a 1 hour layover in Salt Lake City. I found that the Organ was only a block away from Greyhound, and although I was just minutes late for the last tour of the day, some kind soul in the tourist shop personally took me up to the Tabernacle to at least see the organ. She also gave me a little pamphlet that told the history of that organ and how it had been upgraded and tuned up every so many years. Sooner or later, it would seem that synthesized speech and computer control will be added. If it comes in my lifetime, and St. Peter's does also I may be able to do it. If anyone sees the pope, ask him if he would like to hear St. Peter's Organ speak in tongues and talk on the telephone throughout the world while it composes and accompanies itself with background music. I have been thinking about trying to put together a project team to modernizes some of the organs of the world. Any volunteers, financiers, technicians, etc. Alvin H. White, Gen. Sect. G.O.D.S.B.R.A.I.N. Government Online Database Systems Bureau for Resource Allocations to Information Networks [ alvin@cup.portal.com (OR) ..!sun!portal!cup.portal.com!alvin ]
sseidman@polyslo.CalPoly.EDU (The MIDIman) (11/09/90)
csulliva@gandalf.UUCP (Chris Sullivan) writes: > >But the real question, Mr. MIDIman, is why? You going to hold ISDN tele- >conference jam sessions or something? It's a pretty dumb way to go for MIDI No, because my teacher wanted me to talk about possibilities of MIDI and ISDN working together. Whether it can be done or not is exactly what I am supposed to find out. Either way is fine. The topic I chose was a discussion of the sample dump standard, which I am describing a bit anyway. As my paper isn't due for another week, this post came just in time. I would like to thank everyone who sent me or posted info. THANKS. -- /\ PYRAMIDI | sseidman@polyslo.calpoly.edu /--\ RECORDING | Steven R. Seidman /----\ | Tangerine Dream, Level 42, Vangelis, Jarre, Where Analog and Digital Meet | Mannheim Steamroller, Yes, Genesis, ...