FluidSynth ignores LSB in Pitch Bend Range

[spessasus]

FluidSynth version

Execute fluidsynth --version and provide the output.

FluidSynth runtime version 2.3.5
Copyright (C) 2000-2024 Peter Hanappe and others.
Distributed under the LGPL license.
SoundFont(R) is a registered trademark of Creative Technology Ltd.

FluidSynth executable version 2.3.5
Sample type=double

Describe the bug

Provide a clear and concise description of the current situation, e.g. how the bug manifests.

Fluidsynth only allows to specify the pitch bend range in semitones, ignoring the cent tuning via data entry.
Test MIDI file The second note in this file doesn't change its pitch as the bend range is set to 50 cents.

Expected behavior

Provide a clear and concise description of what you expected to happen.

The second note should have a noticeable pitch change when the range is set to 50 cents.

Steps to reproduce

Please explain the steps required to duplicate the issue, esp. if you are able to provide a sample application. E.g. how to start fluidsynth, what shell commands to enter, what midi events to send, etc.

1. Get the file
2. fluidsynth microsoft_gm.sf2 test-rpn-00-00-pitch-bend-range.mid
3. No audible pitch change on the second note

Additional context

Soundfont spec doesn't say anything about the way pitch bend range should be stored so simply doing

float pitchBendRange = semitones + (cents / 100);

should easily fix the problem without further modifications.

[derselbst]

You're welcome to file a PR:

fluidsynth/src/synth/fluid_synth.c

Line 1848 in ad24c8b

/* FIXME - Handle LSB? (Fine bend range in cents) */

[spessasus]

Alright, I created a pull request, I hope it looks good!