FM Lab

Added

• OVERSAMPLE (GLOBAL, last bank, ON to start). The operators run at 88.2 kHz and a half-band filter brings the sound back to 44.1 kHz, so the harmonics FM makes above 22 kHz no longer fold back into the audible range as tones that don't belong to the note: about 40 dB less of them on a bright patch played high. It roughly doubles the engine's CPU: ~72 % (82 % peak) with eight voices, the filter and every effect on. OFF gives that back.
• BIT DEPTH (GLOBAL, last bank): the voices cut to 16, 12 or 8 bits before the filter and the effects, for the sound of older hardware. It starts at 24 BIT, which is FM Lab as before.

Changed

• 24-bit output. The sound used to be cut to 16 bits right after the voices were mixed, and only then sent to the 24-bit DAC. The mix leaves room for an 8-voice chord, so a single soft note used only ~11 of those 16 bits, and its decay ran out of steps and turned gritty (the DC blocker's rounding added a distortion that followed the note). The mix, the filter, the effects and MASTER now carry 24 bits to the DAC. USB audio stays 16-bit and is dithered. The delay's echoes are still stored at 16 bits, which saves 128 KiB of RAM.

Install: download fmlab-1.1.0.fwsc and flash it as described in the README. Settings saved by 1.0.x carry over; OVERSAMPLE starts ON and BIT DEPTH at 24.