[RFC] Support for different reverb engines

[derselbst]

Originally brought up on our mailing list 4 years ago, I have now implemented support for selecting different reverb engines in fluidsynth.

Check out the related PullRequest #1760 or the new reverb overview with audio samples in the API docs.

The different engines can be selected via the newly added string-setting synth.reverb.engine, values are "fdn", "free", "lex", "dat".

Feedback on the newly added engines, their response to the four reverb settings, audio rehearsals, etc., is highly welcome! Also pls. share your thoughts about whether any of those new engines should become the default reverb engine in fluidsynth.

For those who want to give it a try, precompiled binaries are available here:

• Windows 10 x64, x86
• Android
• iOS
• Linux - sry, pls. compile the multi-reverb-support branch yourself.

[spessasus]

Hi,
Sorry for the late reply.
Regarding the post, I firmly believe that FDN is unacceptable as a default reverb engine because of this bug: #1496

A default reverb engine shouldn't cause any distorion, ever.
While I'm not against keeping FDN as a choice, it should be up to the user to pick a reverb engine that has known flaws. By default fluidsynth should ship a reverb engine that's reliable in all cases, so the users don't have to change the defaults to fix bugs.

So my vote goes to either dattorro or Lexverb. Probably the latter given that it's faster.

[derselbst]

I understand your point. Now that I had a few weeks hiatus, I came back to this and did a new rehearsal test. Given the current default settings, lexverb sound much less "busy" than FDN. So people will recognize there's a difference when switching to lexverb. For Datorro I'm not sure if they would, it's quite rich by default. You can also make lexverb more busy, by tweaking the reverb.width param, yet, all the reverb engines respond differently to those four parameters.

@es20490446e You have shown interest in tweaking fluidsynth's reverb before. Would you be interested in trying the 2 new engines lexverb and datorro and provide feedback?