Fluid Ignores transforms when No Controller is used

[spessasus]

FluidSynth version

FluidSynth runtime version 2.3.6
Copyright (C) 2000-2024 Peter Hanappe and others.
Distributed under the LGPL license.
SoundFont(R) is a registered trademark of Creative Technology Ltd.

Describe the bug

Sfspec24.pdf, section 8.2.1

0 No Controller
No controller is to be used. The output of this controller module should be treated as
if its value were set to ‘1’. It should not be a means to turn off a modulator.

No controller means essentially a CC of fixed value 127, mapping to 1. Passing 1 through a bipolar negative transform should result in -1, but fluid treats it as 1.

In the attached soundfont, I disable the default pitch modulator and create a custom one with a 12 semitone range. The secondary source is a No controller bipolar negative, effectively -1. It should invert the pitch wheel's pitch, but it doesn't in fluid.

Expected behavior

The attached soundfont's preset "syn" should have inverted pitch wheel with fixed range of 12 semitones. It doesn't.

Steps to reproduce

1. no_controller.zip
2. fluidsynth no_controller.sf2 -o synth.gain=1
3. play with the pitch wheel
4. it is not inverted like it should
5. compare results with other modulator compliant synths like polyphone or spessasynth

Additional context

Might be related to #1068

[derselbst]

I've created a PR for this problem. In my tests with your soundfont, the pitch wheel is now inverted.