[PD] smooth random numbers

[Roman Haefeli]

On Mon, 2014-02-24 at 15:27 +0100, Ingo wrote:
> Roman, 
> 
> are you using MIDI in theory or "real life"?

Frankly, I use (physical) MIDI quiet rarely and  I'm far from hitting
any of its limits as I mostly use some kind of MIDI controller.

> "Jitter" is MIDI's "alias name".

Yeah, I guess that is true.

> In practice MIDI data is being reduced as much as possible to avoid
> overloading the MIDI bus and in return causing serious timing problems or
> even missing data. Since I would not expect this signal to be the only one
> through the MIDI interface I would actually reduce the data on fast changes
> even drastically more.
> 
> All (decent) MIDI receiving devices interpolate between the values in order
> to avoid zipper noise.

Being even more nit-picking, I say interpolation doesn't address jitter,
though I totally see what you mean. Being that precise doesn't actually
matter that much.

> I see your point - in fact I had the same thought that you had at first!
> I dropped it right away.
> 
> Working on a daily basis with MIDI I know that this is a waste of time.

Waste of programming time or waste of CPU time? The latter doesn't
really make a difference.

> Actually: I would add a [speedlim 5] to reduce data further and you still
> wouldn't hear anything unusual.

I agree that those subtleties are hardly noticable. However, I felt the
need to point out the differences between our approaches, as you removed
what I considered crucial parts of the example.

> That reminds me a little of people asking for 14-bit pitchbend. It would
> take about 11 seconds to move the pitchbend wheel on a keyboard from the
> bottom to the top. Even a 7-bit pitchbend takes more that 80 ms sending all
> values.
> It's impossible to play music with a precise timing like this!
> 
> In practice a very fast volume change going from 0 - 127 usually gets
> reduced to 3-5 numbers in order to allow additional controllers like
> pitchbend and aftertouch to be sent at the same time and still keep the note
> on jitter within a range of maybe 3-8 ms (plus the jitter of the interface
> itself).

Sure, can't argue with that. You are assuming a scenario where this MIDI
fader emulator is used to control real MIDI receivers. I was more
thinking of a scenario where the emulator is used to substitute a real
MIDI controller/sender. There is no precision loss within Pd, so why not
use the "precise" implementation? 

> And BTW - why would "random" need extra precision?
> Doesn't the word random say it all?

No, the endpoints are supposed to be random, not the ramps in between.

> Another neglected thing is the curve that the data change should have. That
> would obviously require some extra calculation. I don't remember reading
> anything about that in the original posting, though.

Me, neither, though in real that is certainly an issue. 

I don't know why I'm so pig-headed with precision. I guess the mere fact
that Pd allows for such implementations makes me want to use them
everywhere. I personally see beauty in this ability of Pd.

Roman