Re: [linux-audio-dev] Synchronizing sound to MIDI events?

Denis de Leeuw Duarte wrote: Hi, Denis, a while ago you posted a question concerning rendering audio in response to midi events. I've been thinking about that problem, too (I'm using PortAudio instead of Jack, but the fundamental problem of rendering the audio with the goal of keeping latency low while avoiding jitter is the same). I don't know whether you got any replies through lad, but I was curious what solution you would eventually come up with, so I filed your mail for later consideration. My background is that I'm developing a functional programming language with MIDI and audio interfaces (based on MidiShare and PortAudio). I've recently started thinking about adding some softsynth functionality to that, so I'm facing exactly the same problem. Probably this is folk knowledge for audio programmers, but it's difficult to find anything on the web about that. I must admit, though, that I haven't taken a look at sources of other softsynth projects like fluidsynth or one of the modular synths out there yet. Well, that being said, I would imagine that you'll have to record the exact offset (from the beginning of the block) at which the midi events came in, and then start rendering at exactly the same offset one or two blocks later, to avoid jitter. (Translating the midi offsets in, say, milliseconds, to sample numbers is trivial, just multiply the time with the samplerate and truncate or round to an integer.) At least that's how I would go about this, but I haven't actually implemented it. So what solution did you come up with, and does it work reasonably well? If you don't mind sharing. :) Cheers, Albert -- Dr. Albert Gr"af Email: Dr.Graef(a)t-online.de, ag(a)muwiinfa.geschichte.uni-mainz.de WWW: http://www.musikwissenschaft.uni-mainz.de/~ag