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// Shim for Safari.
window.AudioContext = window.AudioContext || window.webkitAudioContext
function audioBufferToWav(buffer, opt) {
opt = opt || {}
var numChannels = buffer.numberOfChannels
var sampleRate = buffer.sampleRate
var format = opt.float32 ? 3 : 1
var bitDepth = format === 3 ? 32 : 16
var result
if (numChannels === 2) {
result = interleave(buffer.getChannelData(0), buffer.getChannelData(1))
} else {
result = buffer.getChannelData(0)
}
return encodeWAV(result, format, sampleRate, numChannels, bitDepth)
}
function encodeWAV(samples, format, sampleRate, numChannels, bitDepth) {
var bytesPerSample = bitDepth / 8
var blockAlign = numChannels * bytesPerSample
var buffer = new ArrayBuffer(44 + samples.length * bytesPerSample)
var view = new DataView(buffer)
/* RIFF identifier */
writeString(view, 0, 'RIFF')
/* RIFF chunk length */
view.setUint32(4, 36 + samples.length * bytesPerSample, true)
/* RIFF type */
writeString(view, 8, 'WAVE')
/* format chunk identifier */
writeString(view, 12, 'fmt ')
/* format chunk length */
view.setUint32(16, 16, true)
/* sample format (raw) */
view.setUint16(20, format, true)
/* channel count */
view.setUint16(22, numChannels, true)
/* sample rate */
view.setUint32(24, sampleRate, true)
/* byte rate (sample rate * block align) */
view.setUint32(28, sampleRate * blockAlign, true)
/* block align (channel count * bytes per sample) */
view.setUint16(32, blockAlign, true)
/* bits per sample */
view.setUint16(34, bitDepth, true)
/* data chunk identifier */
writeString(view, 36, 'data')
/* data chunk length */
view.setUint32(40, samples.length * bytesPerSample, true)
if (format === 1) { // Raw PCM
floatTo16BitPCM(view, 44, samples)
} else {
writeFloat32(view, 44, samples)
}
return buffer
}
function interleave(inputL, inputR) {
var length = inputL.length + inputR.length
var result = new Float32Array(length)
var index = 0
var inputIndex = 0
while (index < length) {
result[index++] = inputL[inputIndex]
result[index++] = inputR[inputIndex]
inputIndex++
}
return result
}
function writeFloat32(output, offset, input) {
for (var i = 0; i < input.length; i++, offset += 4) {
output.setFloat32(offset, input[i], true)
}
}
function floatTo16BitPCM(output, offset, input) {
for (var i = 0; i < input.length; i++, offset += 2) {
var s = Math.max(-1, Math.min(1, input[i]))
output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true)
}
}
function writeString(view, offset, string) {
for (var i = 0; i < string.length; i++) {
view.setUint8(offset + i, string.charCodeAt(i))
}
}
// Safari does not support promise-based decodeAudioData, need to use callback instead.
const decodeAudioData = buffer => new Promise((res, rej) => {
new AudioContext().decodeAudioData(buffer, res, rej)
})
const startRecording = async () => {
const data = []
// Ask for mic permissions.
const stream = await navigator.mediaDevices.getUserMedia({ video: false, audio: true })
window.stream = stream
// Use polyfill for older browsers.
if (!window.MediaRecorder) {
window.MediaRecorder = OpusMediaRecorder
window.recorder = new MediaRecorder(stream, {}, {
OggOpusEncoderWasmPath: 'https://cdn.jsdelivr.net/npm/opus-media-recorder@latest/OggOpusEncoder.wasm',
WebMOpusEncoderWasmPath: 'https://cdn.jsdelivr.net/npm/opus-media-recorder@latest/WebMOpusEncoder.wasm'
})
}
else window.recorder = new MediaRecorder(stream)
// Handle incoming data.
window.recorder.ondataavailable = e => data.push(e.data)
window.recorder.start()
window.recorder.onerror = e => { throw e.error || new Error(e.name) }
window.recorder.onstop = async (e) => {
const blob = new Blob(data)
const fetchedBlob = await fetch(URL.createObjectURL(blob))
const arrayBuffer = await fetchedBlob.arrayBuffer()
// Convert to wav format.
const wav = audioBufferToWav(await decodeAudioData(arrayBuffer))
const formData = new FormData()
formData.append('files', new Blob([wav], { type: 'audio/wave' }), 'sound.wav')
// Send the audio file to Wave server.
const res = await fetch(wave.uploadURL, { method: 'POST', body: formData })
const { files } = await res.json()
// Emit event (q.events.audio.captured) with a URL of the audio file at Wave server.
window.wave.emit('audio', 'captured', files[0])
}
}
const stopRecording = () => {
window.recorder.stop()
window.stream.getTracks().forEach(track => track.stop())
}
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