Java Sound crash fixes for Linux. (issue #1)

- Explicitly supply the AudioFormat when creating a Clip.
- Disable Master Gain if unsupported (e.g. in PulseAudio).
- Do not try to play uninitialized sounds (e.g. LineUnavailableException during creation, seems to happen regularly with PulseAudio).

Other changes:
- Errors replaced with debugs in 'getTrackLength()' if audio fields inaccessible.
- Do not log ThreadDeath exceptions (it's a known issue, and only clutters the log file).

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/MusicController.java

@@ -246,7 +246,7 @@ public class MusicController {
 
 	 /**
 	 * Gets the length of the track, in milliseconds.
-	 * Returns 0f if no file is loaded or an MP3 is currently being converted.
+	 * Returns 0 if no file is loaded or an MP3 is currently being converted.
 	 * @author bdk (http://slick.ninjacave.com/forum/viewtopic.php?t=2699)
 	 */
 	public static int getTrackLength() {
@@ -265,7 +265,8 @@ public class MusicController {
 			length.setAccessible(true);
 			duration = (float) (length.get(audio));
 		} catch (Exception e) {
-			Log.error("Could not get track length.", e);
+			Log.debug("Could not get track length.");
+			return 0;
 		}
 		return (int) (duration * 1000);
 	}

src/itdelatrisu/opsu/Opsu.java

@@ -103,6 +103,7 @@ public class Opsu extends StateBasedGame {
 		Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
 			@Override
 			public void uncaughtException(Thread t, Throwable e) {
+				if (!(e instanceof ThreadDeath))  // TODO: see MusicController
 					Log.error("** Uncaught Exception! **", e);
 			}
 		});

src/itdelatrisu/opsu/SoundController.java

@@ -23,9 +23,11 @@ import itdelatrisu.opsu.states.Options;
 import java.io.IOException;
 import java.net.URL;
 
+import javax.sound.sampled.AudioFormat;
 import javax.sound.sampled.AudioInputStream;
 import javax.sound.sampled.AudioSystem;
 import javax.sound.sampled.Clip;
+import javax.sound.sampled.DataLine;
 import javax.sound.sampled.FloatControl;
 import javax.sound.sampled.LineUnavailableException;
 import javax.sound.sampled.UnsupportedAudioFileException;
@@ -154,7 +156,13 @@ public class SoundController {
 		try {
 			URL url = ResourceLoader.getResource(ref);
 			AudioInputStream audioIn = AudioSystem.getAudioInputStream(url);
-			Clip clip = AudioSystem.getClip();
+
+			// GNU/Linux workaround
+//			Clip clip = AudioSystem.getClip();
+			AudioFormat format = audioIn.getFormat();
+			DataLine.Info info = new DataLine.Info(Clip.class, format);
+			Clip clip = (Clip) AudioSystem.getLine(info);
+
 			clip.open(audioIn);
 			return clip;
 		} catch (UnsupportedAudioFileException | IOException | LineUnavailableException e) {
@@ -218,6 +226,9 @@ public class SoundController {
 	 * @param volume the volume [0, 1]
 	 */
 	private static void playClip(Clip clip, float volume) {
+		if (clip == null)  // clip failed to load properly
+			return;
+
 		if (volume > 0f) {
 			// stop clip if running
 			if (clip.isRunning()) {
@@ -225,10 +236,13 @@ public class SoundController {
 				clip.flush();
 			}
 
+			// PulseAudio does not support Master Gain
+			if (clip.isControlSupported(FloatControl.Type.MASTER_GAIN)) {
 				// set volume
 			    FloatControl gainControl = (FloatControl) clip.getControl(FloatControl.Type.MASTER_GAIN);
 			    float dB = (float) (Math.log(volume) / Math.log(10.0) * 20.0);
 				gainControl.setValue(dB);
+			}
 
 			// play clip
 			clip.setFramePosition(0);