Raise `audio.period-size` to `512` for Linux

[fabiangreffrath]

It has been reported against the Debian package that the fluidsynth daemon [1] sucks up a lot of CPU time and [2] causes distortion of pipewire audio. Increasing the period size to the same value as used on Windows was reportedly fixed both of these issues:

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1075976#10
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1105956#25

fluidsynth/src/drivers/fluid_adriver.c

Line 236 in 0949617

fluid_settings_register_int(settings, "audio.period-size", 64, 64, 8192, 0);

[derselbst]

You're suggesting to increase the default latency from 1.4 ms to 11.6ms. I'm not sure if this is musically acceptable for a realtime synthesizer. 64 samples were chosen because it is the smallest unit between which fluidsynth can make state changes. While this provides the most reactive synth feedback, it's also the most expensive one in terms of CPU usage.

If people want to optimize CPU usage, they should take according measure (increasing periods, lowering polyphone, etc. I'm happy to help out if they contribute a documented guide to do so).

If people hear garbage audio when using pipewire, they should consider using another audio driver, a more powerful PC, or increase the period size accordingly.

I'm not convinced that it's worth to change default settings that have existed for so many years now, just because 3 users ran into some issues. Package maintainers are free to override the default values in the systemd config file.

If you're serious about this, please bring up this topic on our mailing list (or here in Github discussion), I would like to hear others' opinions about this.

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PS: The decision to make it 512 on Windows was made before my time in this project. I could ask the other way around: Why not change it back to 64 samples? But I remain conservative about changing default values, sry.