clockbridge.mjsclockbridge.mjs Copyright (C) 2022 Strudel contributors - see https://codeberg.org/uzu/strudel/src/branch/main/packages/superdough/index.mjs This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses/.
thanks freya https://youtu.be/LSNQuFEDOyQ?si=ukZI2IGgWV_NDZzP&t=2979
translates between audio and performance clock
13export class ClockBridge { 14 p; // smoothed clock offset 15 lastTime; 16 audioContext; 17 constructor(audioContext) { 18 this.audioContext = audioContext; 19 } 20 // delta between audio and performance time in ms 21 getOffset() { 22 const { contextTime, performanceTime } = this.audioContext.getOutputTimestamp(); 23 if (!contextTime || !performanceTime) { 24 return; 25 } 26 const offset = performanceTime - contextTime * 1000; // clock offset in ms 27 const dt = performanceTime - (this.lastTime ?? performanceTime); // delta time since last hap 28 const decay = 1 / 10000; // how fast offset changes have an effect 29 this.p = expDecay(this.p ?? offset, offset, decay, dt); // smooth clock offset 30 this.lastTime = performanceTime; 31 return this.p; 32 } 33 getPerformanceTime(audioContextTime) { 34 const offset = this.getOffset(); 35 return audioContextTime * 1000 + offset; // this is now correct in performance time (ms) 36 } 37 getAudioContextTime(performanceTime) { 38 const offset = this.getOffset(); 39 return (performanceTime - offset) / 1000; // this is now correct in audio context time (seconds) 40 } 41}