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export function audioBufferToWav(audioBuffer: AudioBuffer): Uint8Array {
const numOfChan = audioBuffer.numberOfChannels;
const length = audioBuffer.length * numOfChan * 2 + 44;
const buffer = new ArrayBuffer(length);
const view = new DataView(buffer);
let offset = 0;
// Write WAV header
const writeString = function (
view: DataView,
offset: number,
string: string
): void {
for (let i = 0; i < string.length; i++) {
view.setUint8(offset + i, string.charCodeAt(i));
}
};
writeString(view, offset, "RIFF");
offset += 4;
view.setUint32(offset, length - 8, true);
offset += 4;
writeString(view, offset, "WAVE");
offset += 4;
writeString(view, offset, "fmt ");
offset += 4;
view.setUint32(offset, 16, true);
offset += 4; // Sub-chunk size, 16 for PCM
view.setUint16(offset, 1, true);
offset += 2; // PCM format
view.setUint16(offset, numOfChan, true);
offset += 2;
view.setUint32(offset, audioBuffer.sampleRate, true);
offset += 4;
view.setUint32(offset, audioBuffer.sampleRate * 2 * numOfChan, true);
offset += 4;
view.setUint16(offset, numOfChan * 2, true);
offset += 2;
view.setUint16(offset, 16, true);
offset += 2;
writeString(view, offset, "data");
offset += 4;
view.setUint32(offset, audioBuffer.length * numOfChan * 2, true);
offset += 4;
// Write PCM audio data
for (let i = 0; i < audioBuffer.length; i++) {
for (let channel = 0; channel < numOfChan; channel++) {
const sample = Math.max(
-1,
Math.min(1, audioBuffer.getChannelData(channel)[i])
);
view.setInt16(offset, sample * 0x7fff, true);
offset += 2;
}
}
return new Uint8Array(buffer);
}
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