WeiWeiXinNet/Games/game3/js/other/waveAudio.js

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function WAVEAudio(NumChannels, SampleRate, BitsPerSample) {
	this.NumChannels = NumChannels;				//Mono (1), Stereo (2), up to the 2-byte numerical limit.
	this.SampleRate = SampleRate;				//Updates per second for the amplitude.
	this.BitsPerSample = BitsPerSample;			//low quality - 8 bits, high quality - 16 bits.
	this.samples = [];							//Buffer for audio samples.
	this.buildable = false;						//Reserved for sanity checks.
	this.init = function () {
		//First Sanity Check
		if (this.NumChannels >= 0x1 && this.NumChannels <= 0xFFFF && (this.BitsPerSample == 0x8 || this.BitsPerSample == 0x10)) {
			this.buildable = true;
		}
		else {
			throw(new Error("Initial setup values for WAVEAudio were invalid."));
		}
	};
	this.compileWAVE = function () {
		//Convert the buffer data into a raw WAV PCM formated binary stream
		var sampleCount = this.samples.length / this.NumChannels;
		var samplePayloadSize = this.BitsPerSample * this.NumChannels / 0x8;
		var dataPayloadSize = sampleCount * samplePayloadSize;
		var output = "RIFF" + to_little_endian_dword(0x24 + dataPayloadSize) + "WAVE";
		output += "fmt " + to_little_endian_dword(0x10) + to_little_endian_word(0x1) + to_little_endian_word(this.NumChannels) + to_little_endian_dword(this.SampleRate) + to_little_endian_dword(this.SampleRate * samplePayloadSize) + to_little_endian_word(samplePayloadSize) + to_little_endian_word(this.BitsPerSample);
		output += "data" + to_little_endian_dword(dataPayloadSize);
		var index = 0;
		var length = this.samples.length;
		if (this.BitsPerSample == 8) {	//Put this outside the loop for TraceMonkey.
			while (index < length) {
				output += to_byte(this.samples[index++]);
			}
		}
		else {
			while (index < length) {
				output += to_little_endian_word(this.samples[index++]);
			}
		}
		return output;
	};
	this.checkSanity = function (sampleData, isRelative) {
		//WAV PCM Data Sanity Check
		if (this.buildable && sampleData.length == this.NumChannels) {
			for (channel in sampleData) {
				var dataUnit = (isRelative) ? this.convertRelativeUnits(sampleData[channel]) : sampleData[channel];
				switch (this.BitsPerSample) {
					case 0x8:
						if (dataUnit < 0 || dataUnit > 0xFF) {
							return false;
						}
						break;
					case 0x10:
						if (dataUnit < -0x8000 || dataUnit > 0x7FFF) {
							return false;
						}
				}
			}
			return true;
		}
		return false;
	};
	this.convertRelativeUnits = function (sampleData) {
		//Map relative audio values to WAV PCM values.