ref: 44b9a240d4b2dd28737fa7aff37fb7d0582b25d6
parent: 8b0cd72a6095db7f1639dae81c3d8eefd5b814d8
author: dannye <33dannye@gmail.com>
date: Sun Aug 25 05:57:50 EDT 2019
Make pitch_sweep pitch change argument consistent with the other signed magnitude arguments