decoder.java

java实现的多媒体播放器,可以在手机上运行

/**
 *-----------------------------------------------------------------------
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as published
 *   by the Free Software Foundation; either version 2 of the License,or
 *   (at your option) any later version.
 *
 *   This program 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not,write to the Free Software
 *   Foundation,Inc.,675 Mass Ave,Cambridge,MA 02139,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;
  private boolean initialized;
  protected Header hd;

  /**
   *  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 !
    System.gc();
    hd=header;
    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 layer = header.layer();
      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.out.println("only supports mp3 files");
      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;
  }
}