There's an ongoing pull request on the sfizz .sfz player, to support MIDI Polyphonic Expression. One feature of MPE is that you can convert fractional values into an integer note value plus pitch bend. Since each note plays on its own channel, pitch-bend applies per note rather than globally. (sfizz also supports Scala files, but this is different -- it lets you go full Jacob Collier on your sub-sub-sub-semitones. MPE's default settings allow for 1/170th of a semitone pitch resolution.) sfizz works a treat with spacechild1's fantastic vstplugin~ external.

So, if you're comfortable compiling software yourself, you can have fractional notes on a sample player. sfizz was a relatively painless build in Linux. "git clone --recursive" from https://github.com/rullopat/sfizz-ui .

Here's what might have happened if Ligeti had an eighth-tone piano:

Initially, I had tried to use [poly] for voice/channel assignment. It got confused about so many notes so close together, so I ended up making my own version that binds the note number to the channel and duration.

hjh

else/sfz~ has support for mictrotones

What I'm describing here is a way to do microtuning without setting a scale on the player.

Or perhaps I'm just misled by the tuning page's prominent comment about using scales, where transp might be the droid I'm looking for.

This seems to work (didn't try sfont~ this way though).

(It sounds like a transposition message doesn't affect the pitch of previously played notes -- unlike MIDI pitch bend, which is why MPE needs to split up notes among channels. If so, then transp is more convenient than what I did.)

hjh

I thought you wanted particular scales, like 8th tones

My real interest in this is (cheap[1]) just intonation, where both the Pythagorean and the harmonic-series major third enter into it (separated by a syntonic comma). If you'll need to use the pure third in one context and the Pythagorean third in another, then you don't want to reconfigure the instrument's overall tuning midstream; you just want to apply a fractional offset to a note, and be done with it.

There is one other problem, though: with fractional MIDI notes, you may need two or more voices playing different C naturals. Then, which voice should a note-off target? I predict confusion, for instruments like the else samplers, which truncate or round the note number. MPE disambiguates it by addressing channel numbers. So I'd guess that else/sfz~ would have trouble with the microtonal clusters in the little video (as, for that matter, did vanilla's [poly]). So the MPE way is more robust in this aspect.

Come to think of it... why does else/sfz~ truncate note numbers? You're not bound by the limits of the MIDI protocol; why not fully support fractional note numbers? (I guess it's because of a dependency on a sfz library that is stuck in the 80s/90s.)

hjh

[1] There's a neat little paper in Music Theory Online (can't find the reference now) that gives one approach to generating 5-limit JI scales: starting on, say, F, go up by pure 5ths, except every fourth step, adjust the 5th downward by a syntonic comma. Assuming C as the root and applying octave corrections, you'd get F = 2/3 (4/3), C = 1, G = 3/2, D = 9/8, A = 27/16 * 80/81 = 5/3 (pure m6 vs C), E = 5/4, etc with the next comma correction at C#. Doing this on C gives you another variant, as do G and D, completing the set of distinct scales. (The 5th one would start on A and comma-correct on C# and F, which IIRC would replicate the F scale a comma higher, so the author didn't consider that to be distinct.) The right one of these 4 scales can be chosen for different harmony contexts.

Thinking of microtones in terms of applying a single scale to the whole instrument excludes this type of approach. That is, I wasn't ignoring support for scales, but rather, I was deliberately not interested in that.

Come to think of it... why does else/sfz~ truncate note numbers? You're not bound by the limits of the MIDI protocol; why not fully support fractional note numbers?

that is a good request. Open an issue?