freq_bin was converted to double after it was calculated, so there was
a much higher probability it could be 0 instead of some comma number,
which meant that the bars always stayed on top.
The freq_bin in bins_per_group was multiplied only to be divided later,
which could even result in a crash if you set higher buffer size
(like 1000ms) in PlaybackManager, due to rounding errors I presume.
1) The Sound Player visualizer couldn't deal with small sample buffers,
which occur on low sample rates. Now, it simply doesn't update its
buffer, meaning the display is broken on low sample rates. I'm not too
familiar with the visualizer to figure out a proper fix for now, but
this mitigates the issue (and "normal" sample rates still work).
2) Piano wouldn't buffer enough samples for small sample rates, so the
sample count per buffer is now increased to 2^12, introducing minor
amounts of (acceptable) lag.
AK's version should see better inlining behaviors, than the LibM one.
We avoid mixed usage for now though.
Also clean up some stale math includes and improper floatingpoint usage.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
