On Sat, 20 Feb 2016 17:52:20 +0000, Rui Nuno Capela wrote: At least some professional, if not all professional sequencers allow to lock tracks at the current used BPM, then it's possible to give other tracks different BPM. This isn't just needed for freakish polyrhythms, it's a must to sync special effect sounds to film by SMPTE and still to be able to change the BPM for some ambient effect sounds/music. IIUC this is what's the OP produced and wishes to export and import. This might not be provided by a single file standard, but the OP wants to split a file into it's tracks and than import it to a sequencer that allows to use different tempi.

On Sat, 20 Feb 2016 19:08:03 +0000, Rui Nuno Capela wrote: Not the different tempi as a format information, but an exporting sequencer could render the note positions for the different tracks in relation to one BPM information. MIDI track 1 recorded a laser gun shot at 120 BPM at the beginning of bar 2, so the event is at 2 seconds. Without locking the track and changing the speed to 90 BPM the same bar position would be at 2.666 seconds. If you lock the track at 120 BPM, before you change the speed to 90 BPM, the event stays a 2 seconds, but the new position would be at bar 1.4. To lock a track at a special BPM setting doesn't mean it does use this BPM, it means that the sequencer keeps the absolut time position, but calculates new bar positions in relation to the used BPM, when changing the BPM. So if you sync a film, the sound effect of the laser gun always stays at 2 seconds, the time when the human shoots the Martian or vice versa, but you still can change the tempo of the background music. A smart sequencer might even be able to show tracks with different BPMs, but under the hood it's a calculation in relation to one BPM.

On Sat, 20 Feb 2016 22:01:45 +0000, Rui Nuno Capela wrote: Actually Qtractor does support it, you just need to use a reasonable recording technique :p. IIRC, while the Cubase sequencer for the Atari supported polyrhythm, it is dropped for the Windows sequencer. OTOH nowadays sequencers at least provide weak audio track support, so to have some sound effects at fixed times, it would be possible to record them as audio tracks and then to change the MIDI tempo. To edit real polyrhythm, when ever you want, the audio track workaround isn't good, but how often do we compose polyrhythm music? Who is able to name offhand a few known polyrythmic compositions? Assumed somebody is able to name some compositions, how many of those compositions are computer music, that was really composed with several parallel BPMs and not just experimental compositions more or less without countable beats? https://en.wikipedia.org/wiki/Sheik_Yerbouti#Writing_and_recording There are other known popular and even classic compositions and some folk music is based on it, but it's music played by humans and not by computers. However, this even could be done with Qtractor, by simply ignoring the sequencer's meter and recording with a high resolution, IOW by using the sequence in the same way as an anlog tape recorder, without quantisation, without a metronome given by the computer.

On Sat, 20 Feb 2016 14:50:43 -0800 (PST), Len Ovens wrote: FWIW a musician should always care about the audience. When I was young I made pop music, but was inspired by experimental music. For example, kick and bass were two independent instruments for me, each playing it's own line. An academic composer said, that I should play kick and bass unisono. He was mistaken regarding some of my compositions, especially since I composed mostly for myself, but he is right regarding averaged pop music, especially when composed for an audience. There's a vague boarder between well done and incompetence. An audience of people who aren't musicians maybe would notice a bass line independent of the kick in combination with a few other pitfalls, as "too many (rhythm) instruments", "ten good songs in one odd song", they don't notice the root, they just notice something unusual.

Le 20/02/2016 18:52, Rui Nuno Capela a écrit : Ah ! i didn't think of qtractor ! Thank you rncbc, i will try asap ! Indeed, tempo per channel is missing in the MIDI spec itself. I wanted to make a score to reproduce phase shifting like in Steve Reich's Violin Phase (the simplest generative music with 5 notes), but in a MIDI way. I will post something ogg if i can find a way to do this with qtractor. Thanks again, - Benoît P.S: i can't figure out why i didn't try qtractor today, i was focused on commandline midi converters... :-)