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resourcestreamer.js
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resourcestreamer.js
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/*
* Copyright (c) 2022 Shinya Ishikawa.
*
* This file is part of the Moddable SDK Runtime.
*
* The Moddable SDK Runtime is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* The Moddable SDK Runtime is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the Moddable SDK Runtime. If not, see <http://www.gnu.org/licenses/>.
*
*/
/*
Streaming from resource
*/
import Resource from "Resource";
class ResourceStreamer {
#audio;
#stream;
#playing = [];
#bytesQueued = 0;
#targetBytesQueued;
#bytesPerSample = 2;
#bytesPerBlock;
#callbacks = [];
#resource;
constructor(options) {
this.#resource = new Resource(options.path);
this.#resource.position = 12; // skip maud header
const sampleRate = options.audio.sampleRate;
this.#targetBytesQueued = sampleRate * this.#bytesPerSample;
this.#bytesPerBlock = Math.idiv(this.#targetBytesQueued, 8);
if (this.#bytesPerBlock % this.#bytesPerSample)
throw new Error("invalid bytesPerBlock")
if (options.onPlayed)
this.#callbacks.onPlayed = options.onPlayed;
if (options.onError)
this.#callbacks.onError = options.onError;
if (options.onDone)
this.#callbacks.onDone = options.onDone;
const audio = options.audio.out;
this.#audio = audio;
this.#stream = options.audio.stream ?? 0;
audio.callbacks ??= [];
audio.callbacks[this.#stream] = bytes => {
if (!bytes) {
this.#callbacks.onDone?.();
return;
}
this.#bytesQueued -= bytes;
let played = this.#playing.shift();
this.#callbacks.onPlayed?.(played);
played = undefined;
this.#fillQueue();
};
this.#fillQueue();
this.#audio.start();
}
close() {
this.#audio.enqueue(this.#stream, this.#audio.constructor.Flush);
this.#audio.callbacks[this.#stream] = null;
this.#audio = this.#playing = undefined;
}
#fillQueue() {
while ((this.#bytesQueued < this.#targetBytesQueued) &&
(this.#resource.position < this.#resource.byteLength) &&
(this.#audio.length(this.#stream) >= 2)) {
const use = Math.min(this.#targetBytesQueued - this.#bytesQueued, this.#bytesPerBlock)
const slice = this.#resource.slice(this.#resource.position, this.#resource.position + use, false);
this.#resource.position += slice.byteLength;
this.#audio.enqueue(this.#stream, this.#audio.constructor.RawSamples, slice, 1, 0, slice.byteLength / this.#bytesPerSample);
this.#audio.enqueue(this.#stream, this.#audio.constructor.Callback, slice.byteLength);
this.#bytesQueued += slice.byteLength;
this.#playing.push(slice);
if (this.#resource.position === this.#resource.byteLength)
this.#audio.enqueue(0, this.#audio.constructor.Callback, 0);
}
}
}
export default ResourceStreamer;