WAVWriter.hx

/**
 * @author Bernard Visscher [bernard at debit dot nl]
 * ported to haxe
 * http://ralcr.googlecode.com/svn-history/r42/trunk/IOKit/WAVWriter.hx
 */

import flash.utils.Endian;
import flash.utils.ByteArray;

class WAVWriter {
	private var samples:ByteArray;
	
	public function new() {
		 samples = new ByteArray();
		 samples.endian = Endian.LITTLE_ENDIAN;
	}

	/**
	 * The samples given are of the type float, which is the type extracted from the Sound object.
	 */
	public function writeSamples(ba:ByteArray) {
		ba.position = 0;
		while (ba.bytesAvailable > 0) {
			var l:Int = Math.round(ba.readFloat() * 0x7FFF); // * 0x7FFF, because wav samples when 16bits have a value of -2^15 till 2^15
			var r:Int = Math.round(ba.readFloat() * 0x7FFF);
			samples.writeShort(l);
			samples.writeShort(r);
		}
	}
	
	public function getWAV():ByteArray {
		samples.position = 0;
		
		var wav:ByteArray = new ByteArray();
		wav.endian = Endian.BIG_ENDIAN;
		wav.writeUTFBytes("RIFF");
		
		wav.endian = Endian.LITTLE_ENDIAN;
		wav.writeUnsignedInt(samples.bytesAvailable + 36);
		
		wav.endian = Endian.BIG_ENDIAN;
		wav.writeUTFBytes("WAVE");
		
		//subchunk 1
		wav.writeUTFBytes("fmt ");
		
		wav.endian = Endian.LITTLE_ENDIAN;
		wav.writeInt(16); //Subchunk1Size    16 for PCM.  This is the size of the rest of the Subchunk which follows this number.
		wav.writeShort(1); // AudioFormat      PCM = 1
		wav.writeShort(1); // NumChannels      Mono = 1, Stereo = 2, etc.
		wav.writeUnsignedInt(44100); //  SampleRate       8000, 44100, etc.
		wav.writeUnsignedInt(Math.round(44100 * 1 * 16/8)); //ByteRate         == SampleRate * NumChannels * BitsPerSample/8
		wav.writeShort(Math.round(1 * 16/8)); // BlockAlign       == NumChannels * BitsPerSample/8
		wav.writeShort(16); //Bits per sample
		
		//data chunk
		wav.endian = Endian.BIG_ENDIAN;
		wav.writeUTFBytes("data");
		
		wav.endian = Endian.LITTLE_ENDIAN;
		wav.writeUnsignedInt(samples.bytesAvailable);
		wav.writeBytes(samples);
		
		wav.position = 0;
		return wav;
	}
}