@awayjs/core/lib/parsers/WaveAudioParser.ts

AwayJS core classes

import { WaveAudio, WaveAudioData } from '../audio/WaveAudio';
import { URLLoaderDataFormat } from '../net/URLLoaderDataFormat';
import { ParserBase } from '../parsers/ParserBase';
import { ByteArray } from '../utils/ByteArray';

export class WaveAudioParser extends ParserBase {
	constructor() {
		super(URLLoaderDataFormat.BLOB);
	}

	/**
	 * this static property can be set with a function that that will be called
	 * on each filename before adding it to the library
	 */
	public static processFilename=function(filename): string {
		return filename;
	};

	public static supportsType(extension: string): boolean {

		extension = extension.toLowerCase();
		return extension == 'wav' || extension == 'mp3' || extension == 'ogg';

	}

	public static supportsData(data: any): boolean {
		if (!(data instanceof ByteArray))
			return false;

		const ba: ByteArray = <ByteArray> data;
		const filetype: string = WaveAudioParser.parseFileType(ba);
		return filetype ? true : false;
	}

	protected startParsing(frameLimit: number): void {
		//clear content
		delete this._content;
		this._content = null;

		super.startParsing(frameLimit);
	}

	protected proceedParsing(): void {
		this._content = new WaveAudio(new WaveAudioData(this.data));
		this.finalizeAsset(this._content, this.fileName);

		this.finishParsing();
	}

	private static parseFileType(ba: ByteArray): string {

		//old mp3 detections
		// This does not seem to work for all my mp3 files (i tested different mp3 encoders)
		// I leave it in, because it might work for mp3 data that i do not have here to test
		ba.position = 0;
		if ((ba.readUnsignedShort() & 0xFFE0) == 0xFFE0) {
			return 'mp3'; // test for MP3 syncword
		}

		// new mp3 detection
		// this from is-mp3 npm module,
		// but still i have mp3 files that are not detected by this
		// i added the hack: (byte_1 === 255 && byte_2 === 243 && byte_3 === 130) 	to catch those mp3s
		// todo: find a more foolproof way to detect al mp3 (my hack might collide with detection for other filetypes)
		ba.position = 0;
		const byte_1: number = ba.readUnsignedByte();
		const byte_2: number = ba.readUnsignedByte();
		const byte_3: number = ba.readUnsignedByte();
		if ((byte_1 === 73 && byte_2 === 68 && byte_3 === 51)
			|| (byte_1 === 255 && byte_2 === 251) || (byte_1 === 255 && byte_2 === 243 && byte_3 === 130)) {
			return 'mp3';
		}

		ba.position = 0;
		if (ba.readUTFBytes(4) == 'RIFF')
			return 'wav';

		ba.position = 0;
		if (ba.readUTFBytes(4) == 'OggS')
			return 'ogg';

		ba.position = 0;

		return null;
	}
}