Re: [fluid-dev] Perfect, as opposed to Tempered tuning

[R.L. Horn]

On Wed, 29 Oct 2014, Fede Galland wrote:

> I've recently been asking the same questions.

There's been some recent discussion over ticket 103 
(http://sourceforge.net/p/fluidsynth/tickets/103/).

(Which you may be part of.)

One thing that causes problems is that fluidsynth doesn't default to using 
any particular tuning program.  Even bank 0/program 0 has to be set 
explicity.

It's probably not a bad idea always to create a "default" tuning program 
and tell fluidsynth to use it for every channel except, maybe, channel 10:

    # create a default tuning (fluidsynth will fill in the blanks)
    tuning "bank 0/prog 0" 0 0
    # assign it to all channels
    settuning 0 0 0
    settuning 1 0 0
    settuning 2 0 0
    ...

That *should* fix the problem of MIDI streams that assume tuning 0/0 is 
the default.

Another thing is that fluidsynth is extremely conservative about tuning — 
it only tweaks the samples that are already assigned to a given key. 
Many other synths, e.g. timidity, look for a best match for the requested 
frequency.

Both are valid approaches.  Fluidsynth's is better suited for making small 
changes, and might be the only way to deal with multi-instrument programs 
(you wouldn't want to press a kettledrum key and get a bongo instead, for 
example).

On the other hand, fluidsynth doesn't cope well with gross tuning changes. 
The sample file uploaded with ticket 103 is a good example.  It sort of 
tends not to do anything, and a tuning dump makes it clear why:

    ....
    key 116, pitch 11600.00
    key 117, pitch 3359.61
    key 118, pitch 5040.00
    key 119, pitch 4800.00
    key 120, pitch 5280.00
    key 121, pitch 6480.00
    key 122, pitch 4559.61
    key 123, pitch 5519.61
    key 124, pitch 6719.61
    key 125, pitch 6000.00
    key 126, pitch 6240.00
    key 127, pitch 6400.00

All of the action is happening on keys 117 and up, which are likely not to 
have any associated samples (they're well off the right side of an 88-key 
keyboard).  Even if they do, pitching the samples down several octaves 
won't sound very good.  It's enough of a problem that a good argument can 
be made for giving fluidsynth one or more alternate tuning heuristics.

All of which may, or may not, be helpful.  :)