133 lines
3.1 KiB
JavaScript
133 lines
3.1 KiB
JavaScript
var recLength = 0,
|
|
recBuffersL = [],
|
|
recBuffersR = [],
|
|
sampleRate;
|
|
|
|
|
|
self.onmessage = function(e) {
|
|
switch(e.data.command){
|
|
case 'init':
|
|
init(e.data.config);
|
|
break;
|
|
case 'record':
|
|
record(e.data.buffer);
|
|
break;
|
|
case 'exportWAV':
|
|
exportWAV(e.data.type);
|
|
break;
|
|
case 'getBuffer':
|
|
getBuffer();
|
|
break;
|
|
case 'clear':
|
|
clear();
|
|
break;
|
|
}
|
|
};
|
|
|
|
function init(config){
|
|
sampleRate = config.sampleRate;
|
|
}
|
|
|
|
function record(inputBuffer){
|
|
recBuffersL.push(inputBuffer[0]);
|
|
recBuffersR.push(inputBuffer[1]);
|
|
recLength += inputBuffer[0].length;
|
|
}
|
|
|
|
function exportWAV(type){
|
|
var bufferL = mergeBuffers(recBuffersL, recLength);
|
|
var bufferR = mergeBuffers(recBuffersR, recLength);
|
|
var interleaved = interleave(bufferL, bufferR);
|
|
var dataview = encodeWAV(interleaved);
|
|
var audioBlob = new Blob([dataview], { type: type });
|
|
|
|
self.postMessage(audioBlob);
|
|
}
|
|
|
|
function getBuffer() {
|
|
var buffers = [];
|
|
buffers.push( mergeBuffers(recBuffersL, recLength) );
|
|
buffers.push( mergeBuffers(recBuffersR, recLength) );
|
|
self.postMessage(buffers);
|
|
}
|
|
|
|
function clear(){
|
|
recLength = 0;
|
|
recBuffersL = [];
|
|
recBuffersR = [];
|
|
}
|
|
|
|
function mergeBuffers(recBuffers, recLength){
|
|
var result = new Float32Array(recLength);
|
|
var offset = 0;
|
|
for (var i = 0; i < recBuffers.length; i++){
|
|
result.set(recBuffers[i], offset);
|
|
offset += recBuffers[i].length;
|
|
}
|
|
return result;
|
|
}
|
|
|
|
function interleave(inputL, inputR){
|
|
var length = inputL.length + inputR.length;
|
|
var result = new Float32Array(length);
|
|
|
|
var index = 0,
|
|
inputIndex = 0;
|
|
|
|
while (index < length){
|
|
result[index++] = inputL[inputIndex];
|
|
result[index++] = inputR[inputIndex];
|
|
inputIndex++;
|
|
}
|
|
return result;
|
|
}
|
|
|
|
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));
|
|
}
|
|
}
|
|
|
|
function encodeWAV(samples){
|
|
var buffer = new ArrayBuffer(44 + samples.length * 2);
|
|
var view = new DataView(buffer);
|
|
|
|
/* RIFF identifier */
|
|
writeString(view, 0, 'RIFF');
|
|
/* RIFF chunk length */
|
|
view.setUint32(4, 36 + samples.length * 2, 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, 1, true);
|
|
/* channel count */
|
|
view.setUint16(22, 2, true);
|
|
/* sample rate */
|
|
view.setUint32(24, sampleRate, true);
|
|
/* byte rate (sample rate * block align) */
|
|
view.setUint32(28, sampleRate * 4, true);
|
|
/* block align (channel count * bytes per sample) */
|
|
view.setUint16(32, 4, true);
|
|
/* bits per sample */
|
|
view.setUint16(34, 16, true);
|
|
/* data chunk identifier */
|
|
writeString(view, 36, 'data');
|
|
/* data chunk length */
|
|
view.setUint32(40, samples.length * 2, true);
|
|
|
|
floatTo16BitPCM(view, 44, samples);
|
|
|
|
return view;
|
|
}
|