// Example 17-4. PlaySoundStream.java

package je3.sound;
import java.io.*;
import java.net.*;
import javax.sound.sampled.*;
import javax.sound.midi.*;

/**
 * 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 PlaySoundStream {
    // 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( );
        }
    }
}