34 lines
1.1 KiB
TypeScript
34 lines
1.1 KiB
TypeScript
// SPDX-License-Identifier: AGPL-3.0-or-later
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// Audio test helpers.
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import { spawnSync } from 'node:child_process';
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export const hasFfmpeg = spawnSync('ffmpeg', ['-version']).status === 0;
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/** 8 kHz mono 16-bit silence as a wav file. */
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export function silenceWav(seconds = 1) {
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const data = Buffer.alloc(8000 * 2 * seconds);
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const h = Buffer.alloc(44);
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h.write('RIFF', 0);
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h.writeUInt32LE(36 + data.length, 4);
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h.write('WAVEfmt ', 8);
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h.writeUInt32LE(16, 16);
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h.writeUInt16LE(1, 20);
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h.writeUInt16LE(1, 22);
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h.writeUInt32LE(8000, 24);
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h.writeUInt32LE(16000, 28);
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h.writeUInt16LE(2, 32);
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h.writeUInt16LE(16, 34);
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h.write('data', 36);
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h.writeUInt32LE(data.length, 40);
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return Buffer.concat([h, data]);
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}
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/** `silence` s of silence, then `seconds` s of a 440 Hz tone, as an 8 kHz mono 16-bit wav. */
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export function toneWav(seconds = 1, silence = 0) {
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const w = silenceWav(seconds + silence);
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const start = 44 + Math.round(silence * 8000) * 2;
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for (let i = 0; start + i * 2 < w.length; i++)
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w.writeInt16LE(Math.round(6000 * Math.sin((2 * Math.PI * 440 * i) / 8000)), start + i * 2);
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return w;
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}
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