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== javax.sound.sampled.LineUnavailableException ==



<source lang="java">

/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.ru/javaexamples3.
*/
import java.io.IOException;
import java.net.URL;
import javax.sound.midi.InvalidMidiDataException;
import javax.sound.midi.MetaEventListener;
import javax.sound.midi.MetaMessage;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.MidiUnavailableException;
import javax.sound.midi.Sequencer;
import javax.sound.midi.Synthesizer;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;
import javax.sound.sampled.UnsupportedAudioFileException;
/**
* This class plays sounds streaming from a URL: it does not have to preload the
* entire sound into memory before playing it. It is a command-line application
* with no gui. It includes code to convert ULAW and ALAW audio formats to PCM
* so they can be played. Use the -m command-line option before MIDI files.
*/
public class Main {
// Create a URL from the command-line argument and pass it to the
// right static method depending on the presence of the -m (MIDI) option.
public static void main(String[] args) throws Exception {
if (args[0].equals("-m"))
streamMidiSequence(new URL(args[1]));
else
streamSampledAudio(new URL(args[0]));
// Exit explicitly.
// This is needed because the audio system starts background threads.
System.exit(0);
}
/** Read sampled audio data from the specified URL and play it */
public static void streamSampledAudio(URL url) throws IOException, UnsupportedAudioFileException,
LineUnavailableException {
AudioInputStream ain = null; // We read audio data from here
SourceDataLine line = null; // And write it here.
try {
// Get an audio input stream from the URL
ain = AudioSystem.getAudioInputStream(url);
// Get information about the format of the stream
AudioFormat format = ain.getFormat();
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
// If the format is not supported directly (i.e. if it is not PCM
// encoded, then try to transcode it to PCM.
if (!AudioSystem.isLineSupported(info)) {
// This is the PCM format we want to transcode to.
// The parameters here are audio format details that you
// shouldn"t need to understand for casual use.
AudioFormat pcm = new AudioFormat(format.getSampleRate(), 16, format.getChannels(), true,
false);
// Get a wrapper stream around the input stream that does the
// transcoding for us.
ain = AudioSystem.getAudioInputStream(pcm, ain);
// Update the format and info variables for the transcoded data
format = ain.getFormat();
info = new DataLine.Info(SourceDataLine.class, format);
}
// Open the line through which we"ll play the streaming audio.
line = (SourceDataLine) AudioSystem.getLine(info);
line.open(format);
// Allocate a buffer for reading from the input stream and writing
// to the line. Make it large enough to hold 4k audio frames.
// Note that the SourceDataLine also has its own internal buffer.
int framesize = format.getFrameSize();
byte[] buffer = new byte[4 * 1024 * framesize]; // the buffer
int numbytes = 0; // how many bytes
// We haven"t started the line yet.
boolean started = false;
for (;;) { // We"ll exit the loop when we reach the end of stream
// First, read some bytes from the input stream.
int bytesread = ain.read(buffer, numbytes, buffer.length - numbytes);
// If there were no more bytes to read, we"re done.
if (bytesread == -1)
break;
numbytes += bytesread;
// Now that we"ve got some audio data, to write to the line,
// start the line, so it will play that data as we write it.
if (!started) {
line.start();
started = true;
}
// We must write bytes to the line in an integer multiple of
// the framesize. So figure out how many bytes we"ll write.
int bytestowrite = (numbytes / framesize) * framesize;
// Now write the bytes. The line will buffer them and play
// them. This call will block until all bytes are written.
line.write(buffer, 0, bytestowrite);
// If we didn"t have an integer multiple of the frame size,
// then copy the remaining bytes to the start of the buffer.
int remaining = numbytes - bytestowrite;
if (remaining > 0)
System.arraycopy(buffer, bytestowrite, buffer, 0, remaining);
numbytes = remaining;
}
// Now block until all buffered sound finishes playing.
line.drain();
} finally { // Always relinquish the resources we use
if (line != null)
line.close();
if (ain != null)
ain.close();
}
}
// A MIDI protocol constant that isn"t defined by javax.sound.midi
public static final int END_OF_TRACK = 47;
/* MIDI or RMF data from the specified URL and play it */
public static void streamMidiSequence(URL url) throws IOException, InvalidMidiDataException,
MidiUnavailableException {
Sequencer sequencer = null; // Converts a Sequence to MIDI events
Synthesizer synthesizer = null; // Plays notes in response to MIDI events
try {
// Create, open, and connect a Sequencer and Synthesizer
// They are closed in the finally block at the end of this method.
sequencer = MidiSystem.getSequencer();
sequencer.open();
synthesizer = MidiSystem.getSynthesizer();
synthesizer.open();
sequencer.getTransmitter().setReceiver(synthesizer.getReceiver());
// Specify the InputStream to stream the sequence from
sequencer.setSequence(url.openStream());
// This is an arbitrary object used with wait and notify to
// prevent the method from returning before the music finishes
final Object lock = new Object();
// Register a listener to make the method exit when the stream is
// done. See Object.wait() and Object.notify()
sequencer.addMetaEventListener(new MetaEventListener() {
public void meta(MetaMessage e) {
if (e.getType() == END_OF_TRACK) {
synchronized (lock) {
lock.notify();
}
}
}
});
// Start playing the music
sequencer.start();
// Now block until the listener above notifies us that we"re done.
synchronized (lock) {
while (sequencer.isRunning()) {
try {
lock.wait();
} catch (InterruptedException e) {
}
}
}
} finally {
// Always relinquish the sequencer, so others can use it.
if (sequencer != null)
sequencer.close();
if (synthesizer != null)
synthesizer.close();
}
}
}

</source>

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