Decoder.java

/***************************************************************************
 *  JLayerME is a JAVA library that decodes/plays/converts MPEG 1/2 Layer 3.
 *  Project Homepage: http://www.javazoom.net/javalayer/javalayerme.html.
 *  Copyright (C) JavaZOOM 1999-2005.
 *
 *  This library 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 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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 this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *---------------------------------------------------------------------------
 */
package javazoom.jlme.decoder;

public class Decoder {
	private SampleBuffer output;

	private SynthesisFilter filter1;

	private SynthesisFilter filter2;

	private LayerIIIDecoder decoder;

	private int outputFrequency;

	private int outputChannels;

	/**
	 * Constructor for the Decoder object
	 * 
	 * @param header
	 *            Description of Parameter
	 * @param stream
	 *            Description of Parameter
	 */
	public Decoder(Header header, BitStream stream) {
		// E.B Fix - Damned unloaded static fields !
		BitReserve.totbit = 0;
		BitReserve.buf_bit_idx = 0;
		BitReserve.buf_byte_idx = 0;
		BitReserve.offset = 0;
		// End of fix.
		if (header.layer() == 3) {
			// float scalefactor = 48000.0f;
			float scalefactor = 32700.0f;
			int mode = header.mode();

			int channels = mode == Header.SINGLE_CHANNEL ? 1 : 2;
			output = new SampleBuffer(header.frequency(), channels);
			filter1 = new SynthesisFilter(0, scalefactor);
			if (channels == 2) {
				filter2 = new SynthesisFilter(1, scalefactor);
			}
			outputChannels = channels;
			outputFrequency = header.frequency();
			decoder = new LayerIIIDecoder(stream, header, filter1, filter2,
					output, OutputChannels.BOTH_CHANNELS);
		} else {
			System.exit(1);
		}
	}

	/**
	 * Sets the outputBuffer attribute of the Decoder object
	 * 
	 * @param out
	 *            The new outputBuffer value
	 */
	public final void setOutputBuffer(SampleBuffer out) {
		output = out;
	}

	/**
	 * Gets the outputFrequency attribute of the Decoder object
	 * 
	 * @return The outputFrequency value
	 */
	public final int getOutputFrequency() {
		return outputFrequency;
	}

	/**
	 * Gets the outputChannels attribute of the Decoder object
	 * 
	 * @return The outputChannels value
	 */
	public final int getOutputChannels() {
		return outputChannels;
	}

	/**
	 * Gets the outputBlockSize attribute of the Decoder object
	 * 
	 * @return The outputBlockSize value
	 */
	public final int getOutputBlockSize() {
		return SampleBuffer.OBUFFERSIZE;
	}

	/**
	 * Description of the Method
	 * 
	 * @return Description of the Returned Value
	 */
	public final SampleBuffer decodeFrame() {
		output.clear();
		decoder.decodeFrame();
		return output;
	}
}