+ public static int decodeTempo(byte[] bytes) {
+ return 60000000 / (bytes[0] * 65536 + bytes[1] * 256 + bytes[2]);
+ }
+
+ /**
+ * Returns the tempo in the given tick position.
+ * @param tick the tick position for which to return the tempo
+ * @return the tempo at the specified tick position
+ */
+ public static int getTempo(long tick) {
+ if (tempoChanges.size() == 0) return 120;
+ MidiEvent tempoEvent = (MidiEvent)tempoChanges.get(0);
+ if (tempoChanges.size() > 1) {
+ for (int i = 1; i < tempoChanges.size(); i++) {
+ MidiEvent nextTempoEvent = (MidiEvent)tempoChanges.get(i);
+ if (nextTempoEvent.getTick() < tick && nextTempoEvent.getTick() > tempoEvent.getTick())
+ tempoEvent = nextTempoEvent;
+ }
+ }
+ return decodeTempo(((MetaMessage)tempoEvent.getMessage()).getData());
+ }
+
+ /**
+ * Sets the tempo at the given tick position.
+ * @param ticks the tick position
+ */
+ public static void setTempo(long tick, int bpm) {
+ // Checks for a tempo event at the given tick position.
+ MidiEvent tempoEvent = null;
+ Iterator it = tempoChanges.iterator();
+ while(it.hasNext()) {
+ MidiEvent nextTempoEvent = (MidiEvent)it.next();
+ if (nextTempoEvent.getTick() == tick) {
+ tempoEvent = nextTempoEvent;
+ break;
+ }
+ }
+
+ // If none was found, creates and adds a new one.
+ if (tempoEvent == null) {
+ tempoEvent = new MidiEvent(new MetaMessage(), tick);
+ (seq.getTracks())[0].add(tempoEvent);
+ tempoChanges.add(tempoEvent);
+ Collections.sort(tempoChanges, new MidiEventComparator());
+ }
+
+ // Sets the tempo of the event (found or created).
+ try {
+ ((MetaMessage)tempoEvent.getMessage()).setMessage(81, encodeTempo(bpm), 3);
+ } catch (InvalidMidiDataException e) {}
+ }
+
+ /**
+ * Returns the byte array for the given time signature.
+ * @param numerator the numerator of the time signature
+ * @param denominator the denominator of the time signature
+ * @return an array of bytes representing the given time signature
+ */
+ public static byte[] encodeTimeSig(int numerator, int denominator) {
+ byte[] b = {
+ (byte)numerator,
+ (byte)(Math.log(denominator) / Math.log(2)), // logarithm of denominator in base 2
+ (byte)96,
+ (byte)8
+ };
+ return b;
+ }
+ /**
+ * Returns the time signature for the given byte array.
+ * @param an array of four bytes representing the time signature
+ * @return an array of two integers where [0] is the numerator and [1] the denominator
+ */
+ public static int[] decodeTimeSig(byte[] bytes) {
+ int[] t = {
+ (int)bytes[0],
+ (int)(1 << bytes[1])
+ };
+ return t;
+ }
+
+ /**
+ * Returns the time signature in the given tick position.
+ * @param tick the tick position for which to return the time signature
+ * @return an array of two integers where [0] is the numerator and [1] the denominator
+ */
+ public static int[] getTimeSig(long tick) {
+ int[] ts = {4, 4};
+ if (timeSignatures.size() == 0) return ts;
+ MidiEvent timeSigEvent = (MidiEvent)timeSignatures.get(0);
+ if (timeSignatures.size() > 1) {
+ for (int i = 1; i < timeSignatures.size(); i++) {
+ MidiEvent nextTimeSigEvent = (MidiEvent)timeSignatures.get(i);
+ if (nextTimeSigEvent.getTick() <= tick && nextTimeSigEvent.getTick() > timeSigEvent.getTick())
+ timeSigEvent = nextTimeSigEvent;
+ }
+ }
+ return decodeTimeSig(((MetaMessage)timeSigEvent.getMessage()).getData());
+ }
+
+ /**
+ * Sets the time signature at the given tick position.
+ * @param ticks the tick position
+ */
+ public static void setTimeSig(long tick, int numerator, int denominator) {
+ // Checks for a time signature event at the given tick position.
+ MidiEvent timeSigEvent = null;
+ Iterator it = timeSignatures.iterator();
+ while(it.hasNext()) {
+ MidiEvent nextTimeSigEvent = (MidiEvent)it.next();
+ if (nextTimeSigEvent.getTick() == tick) {
+ timeSigEvent = nextTimeSigEvent;
+ break;
+ }
+ }
+
+ // If none was found, creates and adds a new one.
+ if (timeSigEvent == null) {
+ timeSigEvent = new MidiEvent(new MetaMessage(), tick);
+ (seq.getTracks())[0].add(timeSigEvent);
+ timeSignatures.add(timeSigEvent);
+ Collections.sort(timeSignatures, new MidiEventComparator());
+ }
+
+ // Sets the time signature of the event (found or created).
+ try {
+ ((MetaMessage)timeSigEvent.getMessage()).setMessage(88, encodeTimeSig(numerator, denominator), 4);
+ } catch (InvalidMidiDataException e) {}
+ }