gcc/libjava/classpath/javax/sound/sampled/AudioInputStream.java

/*
   Copyright (C) 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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02110-1301 USA.

Linking this library statically or dynamically with other modules is
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.sound.sampled;

import java.io.IOException;
import java.io.InputStream;

/**
 * This is an InputStream which is specialized for reading audio files.
 * In particular it only allows operations to act on a multiple of
 * the audio stream's frame size.
 * @since 1.3
 */
public class AudioInputStream extends InputStream
{
  /** The format of the audio stream.  */
  protected AudioFormat format;

  /** The length of the audio stream in frames.  */
  protected long frameLength;

  /** The current frame position, starting from frame zero.  */
  protected long framePos;

  /** The size of a frame in bytes.  */
  protected int frameSize;

  // I wonder why this class doesn't inherit from FilterInputStream.
  private InputStream input;

  // The saved frame position, used for mark/reset.
  private long markedFramePos;

  /**
   * Create a new AudioInputStream given an underlying InputStream,
   * the audio format, and the length of the data in frames.  The
   * frame size is taken from the format.
   * @param is the underlying input stream
   * @param fmt the format of the data
   * @param length the length of the data in frames
   */
  public AudioInputStream(InputStream is, AudioFormat fmt, long length)
  {
    this.format = fmt;
    this.frameLength = length;
    this.framePos = 0;
    this.frameSize = fmt.getFrameSize();
    this.input = is;
  }

  /**
   * Create a new AudioInputStream given a TargetDataLine.  The audio
   * format and the frame size are taken from the line.
   * @param line the TargetDataLine
   */
  public AudioInputStream(TargetDataLine line)
  {
    this(new TargetInputStream(line), line.getFormat(),
         AudioSystem.NOT_SPECIFIED);
  }

  /**
   * Return the number of bytes available to be read from the
   * underlying stream.  This wrapper method ensures that the result
   * is always a multiple of the frame size.
   */
  public int available() throws IOException
  {
    int result = input.available();
    // Ensure result is a multiple of the frame size.
    if (frameSize != AudioSystem.NOT_SPECIFIED)
      result -= result % frameSize;
    return result;
  }

  /**
   * Close the stream.
   */
  public void close() throws IOException
  {
    input.close();
  }

  /**
   * Get the format associated with this stream.
   * @return the AudioFormat
   */
  public AudioFormat getFormat()
  {
    return format;
  }

  /**
   * Get the length of this stream in frames.  Note that this
   * may be AudioSystem#NOT_SPECIFIED.
   * @return the length of the stream in frames
   */
  public long getFrameLength()
  {
    return frameLength;
  }

  public void mark(int limit)
  {
    input.mark(limit);
    markedFramePos = framePos;
  }

  /**
   * Return true if the underlying stream supports mark and reset,
   * false otherwise.
   */
  public boolean markSupported()
  {
    return input.markSupported();
  }

  /**
   * Read a single byte from the underlying stream.  If the frame
   * size is set, and is not one byte, an IOException will be thrown.
   */
  public int read() throws IOException
  {
    if (frameSize != 1)
      throw new IOException("frame size must be 1 for read()");
    int result;
    if (framePos == frameLength)
      result = -1;
    else
      result = input.read();
    if (result != -1)
      ++framePos;
    return result;
  }

  public int read(byte[] buf) throws IOException
  {
    return read(buf, 0, buf.length);
  }

  public int read(byte[] buf, int offset, int length) throws IOException
  {
    int result;
    if (framePos == frameLength)
      result = -1;
    else
      {
        int myFrameSize = (frameSize == AudioSystem.NOT_SPECIFIED
                           ? 1 : frameSize);
        // Ensure length is a multiple of frame size.
        length -= length % myFrameSize;

        result = 0;
        while (result == 0 || result % myFrameSize != 0)
          {
            int val = input.read(buf, offset, length);
            if (val < 0)
              {
                // This is a weird situation as we might have read a
                // frame already.  It isn't clear at all what to do if
                // we only found a partial frame.  For now we just
                // return whatever we did find.
                if (result == 0)
                  return -1;
                result -= result % myFrameSize;
                break;
              }
            result += val;
          }
        // assert result % myFrameSize == 0;
        framePos += result / myFrameSize;
      }
    return result;
  }

  public void reset() throws IOException
  {
    input.reset();
    framePos = markedFramePos;
  }

  public long skip(long n) throws IOException
  {
    if (frameSize != AudioSystem.NOT_SPECIFIED)
      n -= n % frameSize;
    long actual = input.skip(n);
    if (frameSize != AudioSystem.NOT_SPECIFIED)
      framePos += actual / frameSize;
    return actual;
  }

  private static class TargetInputStream extends InputStream
  {
    private TargetDataLine line;
    private byte[] buf;

    /**
     * Create a new TargetInputStream.
     * @param line the line to wrap
     */
    public TargetInputStream(TargetDataLine line)
    {
      this.line = line;
      // FIXME: do we have to call line.open()?
    }

    public synchronized int read() throws IOException
    {
      if (buf == null)
        buf = new byte[1];
      int count = read(buf, 0, 1);
      if (count < 0)
        return -1;
      return buf[0];
    }

    public int read(byte[] buf, int offset, int length) throws IOException
    {
      return line.read(buf, offset, length);
    }
  }
}