95 lines
3.1 KiB
JavaScript
95 lines
3.1 KiB
JavaScript
"use strict";
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/**
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* Inlined from https://github.com/Jam3/audiobuffer-to-wav/commit/2272eb09bd46a05e50a6d684d908aa6f13c58f63#diff-e727e4bdf3657fd1d798edcd6b099d6e092f8573cba266154583a746bba0f346
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*/
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.audioBufferToWav = audioBufferToWav;
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function interleave(inputL, inputR) {
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const length = inputL.length + inputR.length;
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const result = new Float32Array(length);
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let index = 0;
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let inputIndex = 0;
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while (index < length) {
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result[index++] = inputL[inputIndex];
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result[index++] = inputR[inputIndex];
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inputIndex++;
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}
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return result;
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}
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function writeFloat32(output, offset, input) {
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for (let i = 0; i < input.length; i++, offset += 4) {
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output.setFloat32(offset, input[i], true);
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}
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}
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function floatTo16BitPCM(output, offset, input) {
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for (let i = 0; i < input.length; i++, offset += 2) {
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const s = Math.max(-1, Math.min(1, input[i]));
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output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true);
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}
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}
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function writeString(view, offset, string) {
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for (let i = 0; i < string.length; i++) {
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view.setUint8(offset + i, string.charCodeAt(i));
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}
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}
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function encodeWAV({ samples, format, sampleRate, numChannels, bitDepth, }) {
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const bytesPerSample = bitDepth / 8;
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const blockAlign = numChannels * bytesPerSample;
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const buffer = new ArrayBuffer(44 + samples.length * bytesPerSample);
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const view = new DataView(buffer);
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/* RIFF identifier */
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writeString(view, 0, 'RIFF');
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/* RIFF chunk length */
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view.setUint32(4, 36 + samples.length * bytesPerSample, true);
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/* RIFF type */
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writeString(view, 8, 'WAVE');
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/* format chunk identifier */
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writeString(view, 12, 'fmt ');
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/* format chunk length */
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view.setUint32(16, 16, true);
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/* sample format (raw) */
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view.setUint16(20, format, true);
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/* channel count */
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view.setUint16(22, numChannels, true);
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/* sample rate */
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view.setUint32(24, sampleRate, true);
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/* byte rate (sample rate * block align) */
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view.setUint32(28, sampleRate * blockAlign, true);
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/* block align (channel count * bytes per sample) */
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view.setUint16(32, blockAlign, true);
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/* bits per sample */
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view.setUint16(34, bitDepth, true);
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/* data chunk identifier */
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writeString(view, 36, 'data');
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/* data chunk length */
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view.setUint32(40, samples.length * bytesPerSample, true);
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if (format === 1) {
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// Raw PCM
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floatTo16BitPCM(view, 44, samples);
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}
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else {
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writeFloat32(view, 44, samples);
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}
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return buffer;
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}
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function audioBufferToWav(buffer, opt) {
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const numChannels = buffer.numberOfChannels;
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const { sampleRate } = buffer;
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const format = opt.float32 ? 3 : 1;
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const bitDepth = format === 3 ? 32 : 16;
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let result;
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if (numChannels === 2) {
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result = interleave(buffer.getChannelData(0), buffer.getChannelData(1));
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}
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else {
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result = buffer.getChannelData(0);
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}
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return encodeWAV({
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samples: result,
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format,
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sampleRate,
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numChannels,
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bitDepth,
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});
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}
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