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org.xiph.speex.spi

Class FilteredAudioInputStream

Known Direct Subclasses:
Pcm2SpeexAudioInputStream, Speex2PcmAudioInputStream
public abstract class FilteredAudioInputStream
extends AudioInputStream
A FilteredAudioInputStream is an AudioInputStream with buffers to facilitate transcoding the audio. A first byte array can buffer the data from the underlying inputstream until sufficient data for transcoding is present. A second byte array can hold the transcoded audio data, ready to be read out by the stream user.
Version:
$Revision: 1.2 $
Author:
Marc Gimpel, Wimba S.A. (mgimpel@horizonwimba.com)

Field Summary

static int
DEFAULT_BUFFER_SIZE
The default size of the buffer.
protected byte[]
buf
The internal buffer array where the data is stored.
protected int
count
The index one greater than the index of the last valid byte in the buffer.
protected InputStream
in
The underlying inputStream.
protected int
marklimit
The maximum read ahead allowed after a call to the mark method before subsequent calls to the reset method fail.
protected int
markpos
The value of the pos field at the time the last mark method was called.
protected int
pos
The current position in the buffer.
protected byte[]
prebuf
The internal buffer array where the unfiltered data is temporarily stored.
protected int
precount
The index one greater than the index of the last valid byte in the unfiltered data buffer.
protected int
prepos
The current position in the unfiltered data buffer.
private byte[]
single
Array of size 1, used by the read method to read just 1 byte.

Constructor Summary

FilteredAudioInputStream(InputStream in, AudioFormat format, long length)
Creates a FilteredAudioInputStream and saves its argument, the input stream in, for later use.
FilteredAudioInputStream(InputStream in, AudioFormat format, long length, int size)
Creates a FilteredAudioInputStream with the specified buffer size, and saves its argument, the inputstream in for later use.
FilteredAudioInputStream(InputStream in, AudioFormat format, long length, int size, int presize)
Creates a FilteredAudioInputStream with the specified buffer size, and saves its argument, the inputstream in for later use.

Method Summary

int
available()
Returns the number of bytes that can be read from this inputstream without blocking.
protected void
checkIfStillOpen()
Check to make sure that this stream has not been closed
void
close()
Closes this input stream and releases any system resources associated with the stream.
protected void
fill()
Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks.
protected void
makeSpace()
Free up some space in the buffers.
void
mark(int readlimit)
See the general contract of the mark method of InputStream.
boolean
markSupported()
Tests if this input stream supports the mark and reset methods.
int
read()
See the general contract of the read method of InputStream.
int
read(byte[] b, int off, int len)
Reads bytes from this byte-input stream into the specified byte array, starting at the given offset.
void
reset()
See the general contract of the reset method of InputStream.
long
skip(long n)
See the general contract of the skip method of InputStream.

Field Details

DEFAULT_BUFFER_SIZE

public static final int DEFAULT_BUFFER_SIZE
The default size of the buffer.
Field Value:
2048

buf

protected byte[] buf
The internal buffer array where the data is stored. When necessary, it may be replaced by another array of a different size.

count

protected int count
The index one greater than the index of the last valid byte in the buffer. This value is always in the range 0 through buf.length; elements buf[0] through buf[count-1] contain buffered input data obtained and filtered from the underlying inputstream.

in

protected InputStream in
The underlying inputStream.

marklimit

protected int marklimit
The maximum read ahead allowed after a call to the mark method before subsequent calls to the reset method fail. Whenever the difference between pos and markpos exceeds marklimit, then the mark may be dropped by setting markpos to -1.
See Also:
mark(int), reset()

markpos

protected int markpos
The value of the pos field at the time the last mark method was called.

This value is always in the range -1 through pos. If there is no marked position in the inputstream, this field is -1. If there is a marked position in the inputstream, then buf[markpos] is the first byte to be supplied as input after a reset operation. If markpos is not -1, then all bytes from positions buf[markpos] through buf[pos-1] must remain in the buffer array (though they may be moved to another place in the buffer array, with suitable adjustments to the values of count, pos, and markpos); they may not be discarded unless and until the difference between pos and markpos exceeds marklimit.

See Also:
mark(int), pos

pos

protected int pos
The current position in the buffer. This is the index of the next character to be read from the buf array.

This value is always in the range 0 through count. If it is less than count, then buf[pos] is the next byte to be supplied as input. If it is equal to count, then the next read or skip operation will require more bytes to be read and filtered from the underlying inputstream.

See Also:
buf

prebuf

protected byte[] prebuf
The internal buffer array where the unfiltered data is temporarily stored.

precount

protected int precount
The index one greater than the index of the last valid byte in the unfiltered data buffer. This value is always in the range 0 through prebuf.length; elements prebuf[0] through prebuf[count-1] contain buffered input data obtained from the underlying input stream.

prepos

protected int prepos
The current position in the unfiltered data buffer. This is the index of the next character to be read from the prebuf array.

This value is always in the range 0 through precount. If it is less than precount, then prebuf[pos] is the next byte to be supplied as input. If it is equal to precount, then the next read or skip operation will require more bytes to be read from the contained inputstream.

See Also:
prebuf

single

private final byte[] single
Array of size 1, used by the read method to read just 1 byte.

Constructor Details

FilteredAudioInputStream

public FilteredAudioInputStream(InputStream in,
                                AudioFormat format,
                                long length)
Creates a FilteredAudioInputStream and saves its argument, the input stream in, for later use. An internal buffer array is created and stored in buf.
Parameters:
in - the underlying input stream.
format - the format of this stream's audio data.
length - the length in sample frames of the data in this stream.

FilteredAudioInputStream

public FilteredAudioInputStream(InputStream in,
                                AudioFormat format,
                                long length,
                                int size)
Creates a FilteredAudioInputStream with the specified buffer size, and saves its argument, the inputstream in for later use. An internal buffer array of length size is created and stored in buf.
Parameters:
in - the underlying input stream.
format - the format of this stream's audio data.
length - the length in sample frames of the data in this stream.
size - the buffer sizes.

FilteredAudioInputStream

public FilteredAudioInputStream(InputStream in,
                                AudioFormat format,
                                long length,
                                int size,
                                int presize)
Creates a FilteredAudioInputStream with the specified buffer size, and saves its argument, the inputstream in for later use. An internal buffer array of length size is created and stored in buf.
Parameters:
in - the underlying input stream.
format - the format of this stream's audio data.
length - the length in sample frames of the data in this stream.
size - the buffer size.
presize - the prebuffer size.

Method Details

available

public int available()
            throws IOException
Returns the number of bytes that can be read from this inputstream without blocking.

The available method of FilteredAudioInputStream returns the sum of the the number of bytes remaining to be read in the buffer (count - pos). The result of calling the available method of the underlying inputstream is not used, as this data will have to be filtered, and thus may not be the same size after processing (although subclasses that do the filtering should override this method and use the amount of data available in the underlying inputstream).

Returns:
the number of bytes that can be read from this inputstream without blocking.
See Also:
in

checkIfStillOpen

protected void checkIfStillOpen()
            throws IOException
Check to make sure that this stream has not been closed

close

public void close()
            throws IOException
Closes this input stream and releases any system resources associated with the stream.

fill

protected void fill()
            throws IOException
Fills the buffer with more data, taking into account shuffling and other tricks for dealing with marks. Assumes that it is being called by a synchronized method. This method also assumes that all data has already been read in, hence pos > count.

makeSpace

protected void makeSpace()
Free up some space in the buffers.

mark

public void mark(int readlimit)
See the general contract of the mark method of InputStream.
Parameters:
readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.
See Also:
reset()

markSupported

public boolean markSupported()
Tests if this input stream supports the mark and reset methods. The markSupported method of FilteredAudioInputStream returns true.
Returns:
a boolean indicating if this stream type supports the mark and reset methods.
See Also:
mark(int), reset()

read

public int read()
            throws IOException
See the general contract of the read method of InputStream.
Returns:
the next byte of data, or -1 if the end of the stream is reached.
See Also:
in

read

public int read(byte[] b,
                int off,
                int len)
            throws IOException
Reads bytes from this byte-input stream into the specified byte array, starting at the given offset.

This method implements the general contract of the corresponding read method of the InputStream class. As an additional convenience, it attempts to read as many bytes as possible by repeatedly invoking the read method of the underlying stream. This iterated read continues until one of the following conditions becomes true:

  • The specified number of bytes have been read,
  • The read method of the underlying stream returns -1, indicating end-of-file, or
  • The available method of the underlying stream returns zero, indicating that further input requests would block.
If the first read on the underlying stream returns -1 to indicate end-of-file then this method returns -1. Otherwise this method returns the number of bytes actually read.

Subclasses of this class are encouraged, but not required, to attempt to read as many bytes as possible in the same fashion.

Parameters:
b - destination buffer.
off - offset at which to start storing bytes.
len - maximum number of bytes to read.
Returns:
the number of bytes read, or -1 if the end of the stream has been reached.

reset

public void reset()
            throws IOException
See the general contract of the reset method of InputStream.

If markpos is -1 (no mark has been set or the mark has been invalidated), an IOException is thrown. Otherwise, pos is set equal to markpos.

See Also:
mark(int)

skip

public long skip(long n)
            throws IOException
See the general contract of the skip method of InputStream.
Parameters:
n - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.

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