43 lines
1.5 KiB
TypeScript
43 lines
1.5 KiB
TypeScript
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/*
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Copyright 2022 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import { WorkerPayload } from "./worker";
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import { arrayRescale, arraySmoothingResample } from "../utils/arrays";
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import { PLAYBACK_WAVEFORM_SAMPLES } from "../audio/consts";
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const ctx: Worker = self as any;
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export interface Request {
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data: number[];
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}
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export interface Response {
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waveform: number[];
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}
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ctx.addEventListener("message", async (event: MessageEvent<Request & WorkerPayload>): Promise<void> => {
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const { seq, data } = event.data;
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// First, convert negative amplitudes to positive so we don't detect zero as "noisy".
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const noiseWaveform = data.map((v) => Math.abs(v));
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// Then, we'll resample the waveform using a smoothing approach so we can keep the same rough shape.
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// We also rescale the waveform to be 0-1 so we end up with a clamped waveform to rely upon.
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const waveform = arrayRescale(arraySmoothingResample(noiseWaveform, PLAYBACK_WAVEFORM_SAMPLES), 0, 1);
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ctx.postMessage({ seq, waveform });
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});
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