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From: David O. <da...@ol...> - 2003-11-04 00:38:45
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On Monday 03 November 2003 18.57, Mark Knecht wrote: [...] > If the conversion is not part of LS, then what's the additional > latency incurred when playing a keyboard live? How long are MIDI > event's delayed going through a completely separate app? Is it > deterministic, or will it vary from event to event? If you have an additional process that must be scheduled to process=20 every event, there is a significant risk of increased worst case=20 latency. I'm not sure how likely it is that an event is hit by two=20 "slow" reschedules (one in the MIDI processor and one in LS), but=20 it's most probably possible. RT-Dave, the control engineer, would assume this *will* happen=20 occasionally, effectively doubling the worst case latency, until=20 proven wrong. ;-) There most certainly will be an increase in minimum and average=20 latency, but as long as event processing is done "instantly" (by=20 blocking on input and sending the resulting events instantly; no=20 timers and stuff in the MIDI processor), that effect should be=20 insignificant. (Microseconds...) [...] > On the other hand, since almost all of my MIDI goes through the > Alsa stack somehow, and I view connections with kaconnect, could > that be a place to put these velocity modifiers? Well, that was my first though when I started following this thread -=20 but unfortunately, ALSA runs only on Linux. (And QNX, though I have=20 no idea what state that stuff is in nowadays.) It would be nicer IMHO, if things like the "MIDI corrector" could use=20 some portable plugin API - but OTOH, it can't be all that hard to=20 port it to various APIs. No big deal. What's important is that it=20 runs at the right place in the chain, and that it doesn't add=20 significant latency. [...] > Anyway, the best thought that I have right now is that these curves > Cristian asked me to look at are, at least partially, in existence > to handle stuff like this. I might be wrong, but that's all I've > got right now. Yeah, it sure looks like something like that... //David Olofson - Programmer, Composer, Open Source Advocate =2E- Audiality -----------------------------------------------. | Free/Open Source audio engine for games and multimedia. | | MIDI, modular synthesis, real time effects, scripting,... | `-----------------------------------> http://audiality.org -' --- http://olofson.net --- http://www.reologica.se --- |