fspecii
109 lines
2.8 KiB
JavaScript
109 lines
2.8 KiB
JavaScript
function interleave(inputL, inputR) {
|
|
var length = inputL.length + inputR.length;
|
|
var result = new Int16Array(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) {
|
|
output.setInt16(offset, input[i], true);
|
|
}
|
|
}
|
|
|
|
function writeString(view, offset, string) {
|
|
for (var i = 0; i < string.length; i++) {
|
|
view.setUint8(offset + i, string.charCodeAt(i));
|
|
}
|
|
}
|
|
|
|
function encodeWAV(samples, numChannels, sampleRate) {
|
|
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, numChannels, true);
|
|
/* sample rate */
|
|
view.setUint32(24, sampleRate, true);
|
|
/* byte rate (sample rate * block align) */
|
|
view.setUint32(28, sampleRate * numChannels * 2, true);
|
|
/* block align (channel count * bytes per sample) */
|
|
view.setUint16(32, numChannels * 2, 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;
|
|
}
|
|
|
|
|
|
|
|
var sample_rate = 44100;
|
|
var kbps = 128;
|
|
var channels = 1;
|
|
var mp3encoder = null;
|
|
|
|
var samples_left = null;
|
|
var samples_right = null;
|
|
var first_buffer = true;
|
|
|
|
onmessage = function( ev ) {
|
|
if (!ev.data) return ;
|
|
|
|
if (ev.data.sample_rate) {
|
|
sample_rate = ev.data.sample_rate / 1;
|
|
kbps = ev.data.kbps / 1;
|
|
channels = ev.data.channels / 1;
|
|
|
|
return ;
|
|
}
|
|
|
|
if (first_buffer) {
|
|
samples_left = new Int16Array (ev.data, 0);
|
|
first_buffer = false;
|
|
|
|
if (channels > 1) return ;
|
|
}
|
|
|
|
if (ev.data && channels > 1) {
|
|
samples_right = new Int16Array (ev.data, 0);
|
|
}
|
|
|
|
///
|
|
var interleaved = undefined;
|
|
if (channels > 1) {
|
|
interleaved = interleave(samples_left, samples_right);
|
|
} else {
|
|
interleaved = samples_left;
|
|
}
|
|
|
|
var dataview = encodeWAV(interleaved, channels, sample_rate);
|
|
var audioBlob = new Blob([dataview], { type: 'audio/wav' });
|
|
|
|
postMessage( audioBlob );
|
|
} |