* The AudioSystem class includes many methods that manipulate
* AudioInputStream objects.
* For example, the methods let you:
*
InputStream from which this AudioInputStream
* object was constructed.
*/
private InputStream stream;
/**
* The format of the audio data contained in the stream.
*/
protected AudioFormat format;
/**
* This stream's length, in sample frames.
*/
protected long frameLength;
/**
* The size of each frame, in bytes.
*/
protected int frameSize;
/**
* The current position in this stream, in sample frames (zero-based).
*/
protected long framePos;
/**
* The position where a mark was set.
*/
private long markpos;
/**
* When the underlying stream could only return
* a non-integral number of frames, store
* the remainder in a temporary buffer
*/
private byte[] pushBackBuffer = null;
/**
* number of valid bytes in the pushBackBuffer
*/
private int pushBackLen = 0;
/**
* MarkBuffer at mark position
*/
private byte[] markPushBackBuffer = null;
/**
* number of valid bytes in the markPushBackBuffer
*/
private int markPushBackLen = 0;
/**
* Constructs an audio input stream that has the requested format and length in sample frames,
* using audio data from the specified input stream.
* @param stream the stream on which this AudioInputStream
* object is based
* @param format the format of this stream's audio data
* @param length the length in sample frames of the data in this stream
*/
public AudioInputStream(InputStream stream, AudioFormat format, long length) {
super();
this.format = format;
this.frameLength = length;
this.frameSize = format.getFrameSize();
// any frameSize that is not well-defined will
// cause that this stream will be read in bytes
if( this.frameSize == AudioSystem.NOT_SPECIFIED || frameSize <= 0) {
this.frameSize = 1;
}
this.stream = stream;
framePos = 0;
markpos = 0;
}
/**
* Constructs an audio input stream that reads its data from the target
* data line indicated. The format of the stream is the same as that of
* the target data line, and the length is AudioSystem#NOT_SPECIFIED.
* @param line the target data line from which this stream obtains its data.
* @see AudioSystem#NOT_SPECIFIED
*/
public AudioInputStream(TargetDataLine line) {
TargetDataLineInputStream tstream = new TargetDataLineInputStream(line);
format = line.getFormat();
frameLength = AudioSystem.NOT_SPECIFIED;
frameSize = format.getFrameSize();
if( frameSize == AudioSystem.NOT_SPECIFIED || frameSize <= 0) {
frameSize = 1;
}
this.stream = tstream;
framePos = 0;
markpos = 0;
}
/**
* Obtains the audio format of the sound data in this audio input stream.
* @return an audio format object describing this stream's format
*/
public AudioFormat getFormat() {
return format;
}
/**
* Obtains the length of the stream, expressed in sample frames rather than bytes.
* @return the length in sample frames
*/
public long getFrameLength() {
return frameLength;
}
/**
* Reads the next byte of data from the audio input stream. The audio input
* stream's frame size must be one byte, or an IOException
* will be thrown.
*
* @return the next byte of data, or -1 if the end of the stream is reached
* @throws IOException if an input or output error occurs
* @see #read(byte[], int, int)
* @see #read(byte[])
* @see #available
*/
public int read() throws IOException {
if( frameSize != 1 ) {
throw new IOException("cannot read a single byte if frame size > 1");
}
byte[] data = new byte[1];
int temp = read(data);
if (temp <= 0) {
// we have a weird situation if read(byte[]) returns 0!
return -1;
}
return data[0] & 0xFF;
}
/**
* Reads some number of bytes from the audio input stream and stores them into
* the buffer array b. The number of bytes actually read is
* returned as an integer. This method blocks until input data is
* available, the end of the stream is detected, or an exception is thrown.
* This method will always read an integral number of frames.
* If the length of the array is not an integral number
* of frames, a maximum of b.length - (b.length % frameSize)
* bytes will be read.
*
* @param b the buffer into which the data is read
* @return the total number of bytes read into the buffer, or -1 if there
* is no more data because the end of the stream has been reached
* @throws IOException if an input or output error occurs
* @see #read(byte[], int, int)
* @see #read()
* @see #available
*/
public int read(byte[] b) throws IOException {
return read(b,0,b.length);
}
/**
* Reads up to a specified maximum number of bytes of data from the audio
* stream, putting them into the given byte array.
*
This method will always read an integral number of frames.
* If len does not specify an integral number
* of frames, a maximum of len - (len % frameSize)
* bytes will be read.
*
* @param b the buffer into which the data is read
* @param off the offset, from the beginning of array b, at which
* the data will be written
* @param len the maximum number of bytes to read
* @return the total number of bytes read into the buffer, or -1 if there
* is no more data because the end of the stream has been reached
* @throws IOException if an input or output error occurs
* @see #read(byte[])
* @see #read()
* @see #skip
* @see #available
*/
public int read(byte[] b, int off, int len) throws IOException {
// make sure we don't read fractions of a frame.
if( (len%frameSize) != 0 ) {
len -= (len%frameSize);
if (len == 0) {
return 0;
}
}
if( frameLength != AudioSystem.NOT_SPECIFIED ) {
if( framePos >= frameLength ) {
return -1;
} else {
// don't try to read beyond our own set length in frames
if( (len/frameSize) > (frameLength-framePos) ) {
len = (int) (frameLength-framePos) * frameSize;
}
}
}
int bytesRead = 0;
int thisOff = off;
// if we've bytes left from last call to read(),
// use them first
if (pushBackLen > 0 && len >= pushBackLen) {
System.arraycopy(pushBackBuffer, 0,
b, off, pushBackLen);
thisOff += pushBackLen;
len -= pushBackLen;
bytesRead += pushBackLen;
pushBackLen = 0;
}
int thisBytesRead = stream.read(b, thisOff, len);
if (thisBytesRead == -1) {
return -1;
}
if (thisBytesRead > 0) {
bytesRead += thisBytesRead;
}
if (bytesRead > 0) {
pushBackLen = bytesRead % frameSize;
if (pushBackLen > 0) {
// copy everything we got from the beginning of the frame
// to our pushback buffer
if (pushBackBuffer == null) {
pushBackBuffer = new byte[frameSize];
}
System.arraycopy(b, off + bytesRead - pushBackLen,
pushBackBuffer, 0, pushBackLen);
bytesRead -= pushBackLen;
}
// make sure to update our framePos
framePos += bytesRead/frameSize;
}
return bytesRead;
}
/**
* Skips over and discards a specified number of bytes from this
* audio input stream.
* @param n the requested number of bytes to be skipped
* @return the actual number of bytes skipped
* @throws IOException if an input or output error occurs
* @see #read
* @see #available
*/
public long skip(long n) throws IOException {
// make sure not to skip fractional frames
if( (n%frameSize) != 0 ) {
n -= (n%frameSize);
}
if( frameLength != AudioSystem.NOT_SPECIFIED ) {
// don't skip more than our set length in frames.
if( (n/frameSize) > (frameLength-framePos) ) {
n = (frameLength-framePos) * frameSize;
}
}
long temp = stream.skip(n);
// if no error, update our position.
if( temp%frameSize != 0 ) {
// Throw an IOException if we've skipped a fractional number of frames
throw new IOException("Could not skip an integer number of frames.");
}
if( temp >= 0 ) {
framePos += temp/frameSize;
}
return temp;
}
/**
* Returns the maximum number of bytes that can be read (or skipped over) from this
* audio input stream without blocking. This limit applies only to the next invocation of
* a read or skip method for this audio input stream; the limit
* can vary each time these methods are invoked.
* Depending on the underlying stream,an IOException may be thrown if this
* stream is closed.
* @return the number of bytes that can be read from this audio input stream without blocking
* @throws IOException if an input or output error occurs
* @see #read(byte[], int, int)
* @see #read(byte[])
* @see #read()
* @see #skip
*/
public int available() throws IOException {
int temp = stream.available();
// don't return greater than our set length in frames
if( (frameLength != AudioSystem.NOT_SPECIFIED) && ( (temp/frameSize) > (frameLength-framePos)) ) {
return (int) (frameLength-framePos) * frameSize;
} else {
return temp;
}
}
/**
* Closes this audio input stream and releases any system resources associated
* with the stream.
* @throws IOException if an input or output error occurs
*/
public void close() throws IOException {
stream.close();
}
/**
* Marks the current position in this audio input stream.
* @param readlimit the maximum number of bytes that can be read before
* the mark position becomes invalid.
* @see #reset
* @see #markSupported
*/
public void mark(int readlimit) {
stream.mark(readlimit);
if (markSupported()) {
markpos = framePos;
// remember the pushback buffer
markPushBackLen = pushBackLen;
if (markPushBackLen > 0) {
if (markPushBackBuffer == null) {
markPushBackBuffer = new byte[frameSize];
}
System.arraycopy(pushBackBuffer, 0, markPushBackBuffer, 0, markPushBackLen);
}
}
}
/**
* Repositions this audio input stream to the position it had at the time its
* mark method was last invoked.
* @throws IOException if an input or output error occurs.
* @see #mark
* @see #markSupported
*/
public void reset() throws IOException {
stream.reset();
framePos = markpos;
// re-create the pushback buffer
pushBackLen = markPushBackLen;
if (pushBackLen > 0) {
if (pushBackBuffer == null) {
pushBackBuffer = new byte[frameSize - 1];
}
System.arraycopy(markPushBackBuffer, 0, pushBackBuffer, 0, pushBackLen);
}
}
/**
* Tests whether this audio input stream supports the mark and
* reset methods.
* @return true if this stream supports the mark
* and reset methods; false otherwise
* @see #mark
* @see #reset
*/
public boolean markSupported() {
return stream.markSupported();
}
/**
* Private inner class that makes a TargetDataLine look like an InputStream.
*/
private class TargetDataLineInputStream extends InputStream {
/**
* The TargetDataLine on which this TargetDataLineInputStream is based.
*/
TargetDataLine line;
TargetDataLineInputStream(TargetDataLine line) {
super();
this.line = line;
}
public int available() throws IOException {
return line.available();
}
//$$fb 2001-07-16: added this method to correctly close the underlying TargetDataLine.
// fixes bug 4479984
public void close() throws IOException {
// the line needs to be flushed and stopped to avoid a dead lock...
// Probably related to bugs 4417527, 4334868, 4383457
if (line.isActive()) {
line.flush();
line.stop();
}
line.close();
}
public int read() throws IOException {
byte[] b = new byte[1];
int value = read(b, 0, 1);
if (value == -1) {
return -1;
}
value = (int)b[0];
if (line.getFormat().getEncoding().equals(AudioFormat.Encoding.PCM_SIGNED)) {
value += 128;
}
return value;
}
public int read(byte[] b, int off, int len) throws IOException {
try {
return line.read(b, off, len);
} catch (IllegalArgumentException e) {
throw new IOException(e.getMessage());
}
}
}
}