GitLab

Raised cosine add less audible artifacts when used as volume slew
curve, compared to linear one.

Recurrent calculation of slew cosine is based on:
https://basesandframes.files.wordpress.com/2016/05/rgreenfastermath_gdc02.pdf

Bug: internal b/167251783
Change-Id: Ia9262700ecc0b9f4ee5e3895cc9864480eabab73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2391894Reviewed-by: Kenneth MacKay <kmackay@chromium.org>
Commit-Queue: Kenneth MacKay <kmackay@chromium.org>
Auto-Submit: Michael Montvelishsky <mont@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804478}