These #defines are located in desktop_settings.h and allow you to edit
how many samples are discarded per packet. The idea was to use this to
test the MCU-side code and ensure that it doesn't corrupt a packet per
frame, but this seems to have magically disappeared (???).
I remember queueing USB transfers a long time ago, but can't remember
this having any success. It's more likely to just be a random clock
skew issue that only appears on some boards - and it's only "fixed" on
the one particular test board I have in hand now. I think.
EspoTek