This program is based on https://uglyduck.vajn.icu/ep/archive/2018/01/MIDI_Note_Velocity_for_Korg_Volca_FM.html by Emil.
The original code itself is here: https://uglyduck.vajn.icu/Korg_Volca_FM/fw/volca_fw.zip.
This version implements proper QAM demodulator that fixes problems with decoding some firmwares (notably volcasample_sys_BETA7.wav).