scratchfoundation/scratch-audio
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More refactoring/code-cleanup addressing PR comments.

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This commit is contained in:
Karishma Chadha 2018-04-13 17:46:09 -04:00
parent 158adb0868
commit a3ecd2ddc2
1 changed files with 33 additions and 27 deletions
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60
src/index.js
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@ -15,6 +15,27 @@ const ADPCMSoundDecoder = require('./ADPCMSoundDecoder');
* that handles global functionality, and AudioPlayers, belonging to individual sprites and clones.
*/
/**
* Wrapper to ensure that audioContext.decodeAudioData is a promise
* @param {object} audioContext The current AudioContext
* @param {ArrayBuffer} buffer Audio data buffer to decode
* @return {Promise} A promise that resolves to the decoded audio
*/
const decodeAudioData = function (audioContext, buffer) {
// Check for newer promise-based API
if (audioContext.decodeAudioData.length === 1) {
return audioContext.decodeAudioData(buffer);
}
// Fall back to callback API
return new Promise((resolve, reject) => {
audioContext.decodeAudioData(buffer,
decodedAudio => resolve(decodedAudio),
error => reject(error)
);
});
};
class AudioPlayer {
/**
* Each sprite or clone has an audio player
@ -192,32 +213,18 @@ class AudioEngine {
* @returns {?Promise} - a promise which will resolve to the soundId if decoded and stored.
*/
decodeSound (sound) {
const soundId = uid();
let loaderPromise = null;
// Make a copy of the buffer because decoding detaches the original buffer
const bufferCopy1 = sound.data.buffer.slice(0);
// Attempt to decode the sound using the browser's native audio data decoder
// Check for newer promise-based API
if (this.audioContext.decodeAudioData.length === 1) {
loaderPromise = this.audioContext.decodeAudioData(bufferCopy1);
} else {
// Fall back to callback API
loaderPromise = new Promise((resolve, reject) => {
this.audioContext.decodeAudioData(bufferCopy1,
decodedAudio => resolve(decodedAudio),
error => reject(error)
);
});
}
const soundId = uid();
// Partially apply updateSoundBuffer function with the current
// soundId so that it's ready to be used on successfully decoded audio
const addDecodedAudio = this.updateSoundBuffer.bind(this, soundId);
const storedContext = this;
return loaderPromise.then(
decodedAudio => {
storedContext.updateSoundBuffer(soundId, decodedAudio);
return soundId;
},
// Attempt to decode the sound using the browser's native audio data decoder
// If that fails, attempt to decode as ADPCM
return decodeAudioData(this.audioContext, bufferCopy1).then(
addDecodedAudio,
() => {
// The audio context failed to parse the sound data
// we gave it, so try to decode as 'adpcm'
@ -227,10 +234,7 @@ class AudioEngine {
// Try decoding as adpcm
return (new ADPCMSoundDecoder(this.audioContext)).decode(bufferCopy2)
.then(
decodedAudio => {
storedContext.updateSoundBuffer(soundId, decodedAudio);
return soundId;
},
addDecodedAudio,
sndError => {
log.warn('audio data could not be decoded', sndError);
}
@ -249,12 +253,14 @@ class AudioEngine {
}
/**
* Update the in-memory audio buffer to a new one by soundId.
* Add or update the in-memory audio buffer to a new one by soundId.
* @param {!string} soundId - the id of the sound buffer to update.
* @param {AudioBuffer} newBuffer - the new buffer to swap in.
* @return {string} The uid of the sound that was updated or added
*/
updateSoundBuffer (soundId, newBuffer) {
this.audioBuffers[soundId] = newBuffer;
return soundId;
}
/**