On Thu, Jan 27, 2022 at 5:27 PM Tim <termtech@rogers.com> wrote:

On 1/27/22 1:08 PM, Paul Davis wrote:

Hiya Paul. Could you explain that a bit more?

Human exponential vs. linear, I don't quite understand.

Let's suppose you are playing the simplest of beats, let's say you just play a note/tone at 120bpm. There's 0.5 seconds between your playing.

To do a linear speedup, you would gradually reduce the time between notes, maybe like this: 0.5, 0.45, 0.40, 0.35, 0.30 and so on

Problem is, it turns out that humans (even the musical among us) are not very good at all at measuring absolute time. What we are good at is measuring relative time, and so what actually happens is that we decrease (or increase) the "time per note" by a constant *factor*. Let's say the factor is 0.1. So now, the first note of our nominal accelarando is 0.45 long, but the next one is 0.405 then 0.3645 then 0.3285 and so forth. This forms a natural exponential progression.

Put a different way, human performers do not speed up or slow down by a constant amount per beat of an accelerando or decelerando, they speed up or slow down by a constant ratio.

This behavior has been noted in several research papers on human musical performance, and it is very, very difficult for most humans to do anything else.

And can you remember which types of, or specific, plugins would fail, and why? I'd like to investigate.

Alas, I have no specific info on this. x42/robin gareus might know more. Not many plugins care about the tempo map. The ones that do have a lot of potential for screwing up if they come with some baked in idea of "this is what accelerando sounds like".

OK cool thanks. Yeah I thought it might be something like that, a natural tempo factor per unit time.

I'm sure there must be specific written or recorded exceptions though.

Ironic: Right now I'm helping with a user's problem with a midi file song, "Hallelujah", which actually

 has a _linear_ tempo ramp-down at song end.

I'm not so concerned with plugins, just basic time-line tempo and signature mirroring between apps.

Although, you once warned me that different apps or plugins will have different ideas about it.

From both our perspectives we enjoy the monolithic way, with our DAWs. I read you say a few years ago

 that you now tend to prefer that. Well of course, given Ardour has had midi for a while now ;-)

So it may be a moot feature these days, for any serious musical work. Unless one prefers modular projects?

But before Ardour had midi, I longed for the day when our two apps could sit side-by-side and share a time-line.

T.