scratchfoundation/scratch-audio
1
0
Fork 0
mirror of https://github.com/scratchfoundation/scratch-audio.git synced 2024-12-22 14:02:29 -05:00
Code Issues Projects Releases Packages Wiki Activity Actions

cleanup and return a promise

Browse source
This commit is contained in:
Eric Rosenbaum 2016-11-19 14:17:43 -05:00
parent 5fa9bdf1c9
commit d2eb771eea
1 changed files with 75 additions and 63 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

138
src/ADPCMSoundLoader.js
View file

@ -5,77 +5,89 @@ ADPCMSoundLoader loads wav files that have been compressed with the ADPCM format
based on code from Scratch-Flash:
https://github.com/LLK/scratch-flash/blob/master/src/sound/WAVFile.as
to do: I think this will ultimately need to run in a web worker
*/
var ArrayBufferStream = require('./ArrayBufferStream');
var Tone = require('tone');
var log = require('./log');
function ADPCMSoundLoader (url) {
var request = new XMLHttpRequest();
request.open('GET', url, true);
request.responseType = 'arraybuffer';
request.onload = function () {
var audioData = request.response;
var stream = new ArrayBufferStream(audioData);
var riffStr = stream.readUint8String(4);
if (riffStr != 'RIFF') {
log.warn('incorrect adpcm wav header');
}
var lengthInHeader = stream.readInt32();
if ((lengthInHeader + 8) != audioData.byteLength) {
log.warn('adpcm wav length in header: ' + length + 'is incorrect');
}
var wavStr = stream.readUint8String(4);
if (wavStr != 'WAVE') {
log.warn('incorrect adpcm wav header');
}
var formatChunk = this.extractChunk('fmt ', stream);
this.encoding = formatChunk.readUint16();
this.channels = formatChunk.readUint16();
this.samplesPerSecond = formatChunk.readUint32();
this.bytesPerSecond = formatChunk.readUint32();
this.blockAlignment = formatChunk.readUint16();
this.bitsPerSample = formatChunk.readUint16();
formatChunk.position += 2; // skip extra header byte count
this.samplesPerBlock = formatChunk.readUint16();
this.adpcmBlockSize = ((this.samplesPerBlock - 1) / 2) + 4; // block size in bytes
var samples = this.imaDecompress(this.extractChunk('data', stream), this.adpcmBlockSize);
var buffer = Tone.context.createBuffer(1, samples.length, this.samplesPerSecond);
// todo: optimize this?
for (var i=0; i<samples.length; i++) {
buffer.getChannelData(0)[i] = samples[i] / 32768;
}
var source = Tone.context.createBufferSource();
source.buffer = buffer;
source.connect(Tone.Master);
source.start();
}.bind(this);
request.send();
this.stepTable = [
7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230,
253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963,
1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327,
3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487,
12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767];
this.indexTable = [
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8];
function ADPCMSoundLoader () {
}
ADPCMSoundLoader.prototype.load = function (url) {
return new Promise(function (resolve, reject) {
var request = new XMLHttpRequest();
request.open('GET', url, true);
request.responseType = 'arraybuffer';
request.onload = function () {
var audioData = request.response;
var stream = new ArrayBufferStream(audioData);
var riffStr = stream.readUint8String(4);
if (riffStr != 'RIFF') {
log.warn('incorrect adpcm wav header');
reject();
}
var lengthInHeader = stream.readInt32();
if ((lengthInHeader + 8) != audioData.byteLength) {
log.warn('adpcm wav length in header: ' + lengthInHeader + ' is incorrect');
}
var wavStr = stream.readUint8String(4);
if (wavStr != 'WAVE') {
log.warn('incorrect adpcm wav header');
reject();
}
var formatChunk = this.extractChunk('fmt ', stream);
this.encoding = formatChunk.readUint16();
this.channels = formatChunk.readUint16();
this.samplesPerSecond = formatChunk.readUint32();
this.bytesPerSecond = formatChunk.readUint32();
this.blockAlignment = formatChunk.readUint16();
this.bitsPerSample = formatChunk.readUint16();
formatChunk.position += 2; // skip extra header byte count
this.samplesPerBlock = formatChunk.readUint16();
this.adpcmBlockSize = ((this.samplesPerBlock - 1) / 2) + 4; // block size in bytes
var samples = this.imaDecompress(this.extractChunk('data', stream), this.adpcmBlockSize);
// this line is the only place Tone is used here, should be possible to remove
var buffer = Tone.context.createBuffer(1, samples.length, this.samplesPerSecond);
// todo: optimize this? e.g. replace the divide by storing 1/32768 and multiply?
for (var i=0; i<samples.length; i++) {
buffer.getChannelData(0)[i] = samples[i] / 32768;
}
resolve(buffer);
}.bind(this);
request.send();
}.bind(this));
};
ADPCMSoundLoader.prototype.stepTable = [
7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230,
253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963,
1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327,
3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487,
12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767];
ADPCMSoundLoader.prototype.indexTable = [
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8];
ADPCMSoundLoader.prototype.extractChunk = function (chunkType, stream) {
stream.position = 12;
while (stream.position < (stream.getLength() - 8)) {