What is the current State of MIDI I/O?Daniel V. Oppenheim music at watson.ibm.comWed Dec 1 16:21:31 UTC 1999
--=====================_14947071==_.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed Following are some initial observations on MIDI I/O. I would appreciate a pointer to more detailed information, future plans, etc. before I plunge in... I have been looking at the MIDI I/O primitives in Squeak 2.5, on Windows NT. It seems that there are two classes: SimpleMidiPort and MidiPrimTester. Seems that SimpleMidiPort is intended for public use. However, it lacks some of the primitives found in the MidiPrimTester. For example, I copied the primMidiGetClock primitive from the MidiPrimTester, hoping to be able to schedule events into the future. However, the time argument in primMIDIWritePort:from:at: is relative to the time the call is made. So at: 0 plays now, at: 500 in half a second. This means that scheduling has to be handled entirely by Squeak (whereas I was hoping I could get currentTime and then schedule events into the future relative to it using a much more relaxed algorithm). What is the buffer size for the MidiOut? Will the output buffer sort MIDI events if they are given out of time -sequence? If so, will sorting be smart, so say schedule controls and note-off events before note-on events with the same onset? From what I could tell, Midi input seems to lack in several respects: 1. no time stamps on incoming events. This can really hinder serious real-time interaction with Squeak. I'm not sure if one could make a MIDI recording that maintains correct expressive timing, especially if squeak is simultaneously working on other tasks and/or MIDI playback. 2. data comes in a byte stream, rather than already parsed into events. Extra work on the Squeak side. 3. no notification of midi input from system into squeak (using a semaphore for example). One must therefore implement a pooling loop when expecting input. 4. it would be nice to be able to flush the buffer. (this is picky, it can easily be done from squeak). Synchronized MIDI and Audio output. I'm pretty sure you can schedule wave audio from Squeak. Can MIDI and Audio play simultaneously? Can they be synchronized -- say if one has a score comprising both MIDI and SoundFiles events? If so, is this ability platform specific or does it work cross platform? Has anyone given any thought to adopting something like MidiShare (http://www.grame.fr/)? It is in the public domain, supported on most platforms, and quite rich in nifty and useful features. Thanks! Danny Oppenheim --- Dr. Daniel V. Oppenheim Computer Music Center IBM T.J. Watson Research Center phone: (914) 945-1989 P. O. Box 218 (or Route 134) fax: (914) 945-3434 Yorktown Heights, NY 10598 www.research.ibm.com/music --=====================_14947071==_.ALT Content-Type: text/html; charset="us-ascii" <html> Following are some initial observations on MIDI I/O. I would appreciate a pointer to more detailed information, future plans, etc. before I plunge in...<br> <br> I have been looking at the MIDI I/O primitives in Squeak 2.5, on Windows NT. It seems that there are two classes: SimpleMidiPort and MidiPrimTester. Seems that SimpleMidiPort is intended for public use. However, it lacks some of the primitives found in the MidiPrimTester.<br> <br> For example, I copied the primMidiGetClock primitive from the MidiPrimTester, hoping to be able to schedule events into the future. However, the time argument in primMIDIWritePort:from:at: is relative to the time the call is made. So at: 0 plays now, at: 500 in half a second. This means that scheduling has to be handled entirely by Squeak (whereas I was hoping I could get currentTime and then schedule events into the future relative to it using a much more relaxed algorithm). <br> <br> What is the buffer size for the MidiOut?<br> <br> Will the output buffer sort MIDI events if they are given out of time -sequence?<br> <br> If so, will sorting be smart, so say schedule controls and note-off events before note-on events with the same onset?<br> <br> From what I could tell, Midi input seems to lack in several respects:<br> <br> 1. no time stamps on incoming events. This can really hinder serious real-time interaction with Squeak. I'm not sure if one could make a MIDI recording that maintains correct expressive timing, especially if squeak is simultaneously working on other tasks and/or MIDI playback.<br> 2. data comes in a byte stream, rather than already parsed into events. Extra work on the Squeak side.<br> 3. no notification of midi input from system into squeak (using a semaphore for example). One must therefore implement a pooling loop when expecting input.<br> 4. it would be nice to be able to flush the buffer. (this is picky, it can easily be done from squeak).<br> <br> Synchronized MIDI and Audio output. I'm pretty sure you can schedule wave audio from Squeak. Can MIDI and Audio play simultaneously? Can they be synchronized -- say if one has a score comprising both MIDI and SoundFiles events? If so, is this ability platform specific or does it work cross platform?<br> <br> Has anyone given any thought to adopting something like MidiShare (<a href="http://www.grame.fr/" eudora="autourl"><font color="#0000FF"><u>http://www.grame.fr/</a></u>)</font>? It is in the public domain, supported on most platforms, and quite rich in nifty and useful features.<br> <br> Thanks!<br> <br> <x-tab> </x-tab>Danny Oppenheim<br> <br> <br> <br> <div>---</div> <br> <div>Dr. Daniel V. Oppenheim </div> <div><x-tab> </x-tab>Computer Music Center</div> <div><x-tab> </x-tab>IBM T.J. Watson Research Center<x-tab> </x-tab> phone: (914) 945-1989</div> <div><x-tab> </x-tab>P. O. Box 218 (or Route 134)<x-tab> </x-tab> fax: (914) 945-3434 </div> <div><x-tab> </x-tab>Yorktown Heights, NY 10598<x-tab> </x-tab> <a href="http://www.research.ibm.com/music" EUDORA=AUTOURL>www.research.ibm.com/music</a> </div> <br> </html> --=====================_14947071==_.ALT--
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