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package com.sun.media.sound;

import javax.sound.midi.*;
import java.util.ArrayList;

// TODO:
// - define and use a global symbolic constant for 60000000 (see convertTempo)

Some utilities for MIDI (some stuff is used from javax.sound.midi)
Author:Florian Bomers
/** * Some utilities for MIDI (some stuff is used from javax.sound.midi) * * @author Florian Bomers */
public final class MidiUtils { public final static int DEFAULT_TEMPO_MPQ = 500000; // 120bpm public final static int META_END_OF_TRACK_TYPE = 0x2F; public final static int META_TEMPO_TYPE = 0x51;
Suppresses default constructor, ensuring non-instantiability.
/** * Suppresses default constructor, ensuring non-instantiability. */
private MidiUtils() { }
return true if the passed message is Meta End Of Track
/** return true if the passed message is Meta End Of Track */
public static boolean isMetaEndOfTrack(MidiMessage midiMsg) { // first check if it is a META message at all if (midiMsg.getLength() != 3 || midiMsg.getStatus() != MetaMessage.META) { return false; } // now get message and check for end of track byte[] msg = midiMsg.getMessage(); return ((msg[1] & 0xFF) == META_END_OF_TRACK_TYPE) && (msg[2] == 0); }
return if the given message is a meta tempo message
/** return if the given message is a meta tempo message */
public static boolean isMetaTempo(MidiMessage midiMsg) { // first check if it is a META message at all if (midiMsg.getLength() != 6 || midiMsg.getStatus() != MetaMessage.META) { return false; } // now get message and check for tempo byte[] msg = midiMsg.getMessage(); // meta type must be 0x51, and data length must be 3 return ((msg[1] & 0xFF) == META_TEMPO_TYPE) && (msg[2] == 3); }
parses this message for a META tempo message and returns the tempo in MPQ, or -1 if this isn't a tempo message
/** parses this message for a META tempo message and returns * the tempo in MPQ, or -1 if this isn't a tempo message */
public static int getTempoMPQ(MidiMessage midiMsg) { // first check if it is a META message at all if (midiMsg.getLength() != 6 || midiMsg.getStatus() != MetaMessage.META) { return -1; } byte[] msg = midiMsg.getMessage(); if (((msg[1] & 0xFF) != META_TEMPO_TYPE) || (msg[2] != 3)) { return -1; } int tempo = (msg[5] & 0xFF) | ((msg[4] & 0xFF) << 8) | ((msg[3] & 0xFF) << 16); return tempo; }
converts
1 - MPQ-Tempo to BPM tempo
2 - BPM tempo to MPQ tempo
/** * converts<br> * 1 - MPQ-Tempo to BPM tempo<br> * 2 - BPM tempo to MPQ tempo<br> */
public static double convertTempo(double tempo) { if (tempo <= 0) { tempo = 1; } return ((double) 60000000l) / tempo; }
convert tick to microsecond with given tempo. Does not take tempo changes into account. Does not work for SMPTE timing!
/** * convert tick to microsecond with given tempo. * Does not take tempo changes into account. * Does not work for SMPTE timing! */
public static long ticks2microsec(long tick, double tempoMPQ, int resolution) { return (long) (((double) tick) * tempoMPQ / resolution); }
convert tempo to microsecond with given tempo Does not take tempo changes into account. Does not work for SMPTE timing!
/** * convert tempo to microsecond with given tempo * Does not take tempo changes into account. * Does not work for SMPTE timing! */
public static long microsec2ticks(long us, double tempoMPQ, int resolution) { // do not round to nearest tick //return (long) Math.round((((double)us) * resolution) / tempoMPQ); return (long) ((((double)us) * resolution) / tempoMPQ); }
Given a tick, convert to microsecond
Params:
  • cache – tempo info and current tempo
/** * Given a tick, convert to microsecond * @param cache tempo info and current tempo */
public static long tick2microsecond(Sequence seq, long tick, TempoCache cache) { if (seq.getDivisionType() != Sequence.PPQ ) { double seconds = ((double)tick / (double)(seq.getDivisionType() * seq.getResolution())); return (long) (1000000 * seconds); } if (cache == null) { cache = new TempoCache(seq); } int resolution = seq.getResolution(); long[] ticks = cache.ticks; int[] tempos = cache.tempos; // in MPQ int cacheCount = tempos.length; // optimization to not always go through entire list of tempo events int snapshotIndex = cache.snapshotIndex; int snapshotMicro = cache.snapshotMicro; // walk through all tempo changes and add time for the respective blocks long us = 0; // microsecond if (snapshotIndex <= 0 || snapshotIndex >= cacheCount || ticks[snapshotIndex] > tick) { snapshotMicro = 0; snapshotIndex = 0; } if (cacheCount > 0) { // this implementation needs a tempo event at tick 0! int i = snapshotIndex + 1; while (i < cacheCount && ticks[i] <= tick) { snapshotMicro += ticks2microsec(ticks[i] - ticks[i - 1], tempos[i - 1], resolution); snapshotIndex = i; i++; } us = snapshotMicro + ticks2microsec(tick - ticks[snapshotIndex], tempos[snapshotIndex], resolution); } cache.snapshotIndex = snapshotIndex; cache.snapshotMicro = snapshotMicro; return us; }
Given a microsecond time, convert to tick. returns tempo at the given time in cache.getCurrTempoMPQ
/** * Given a microsecond time, convert to tick. * returns tempo at the given time in cache.getCurrTempoMPQ */
public static long microsecond2tick(Sequence seq, long micros, TempoCache cache) { if (seq.getDivisionType() != Sequence.PPQ ) { double dTick = ( ((double) micros) * ((double) seq.getDivisionType()) * ((double) seq.getResolution())) / ((double) 1000000); long tick = (long) dTick; if (cache != null) { cache.currTempo = (int) cache.getTempoMPQAt(tick); } return tick; } if (cache == null) { cache = new TempoCache(seq); } long[] ticks = cache.ticks; int[] tempos = cache.tempos; // in MPQ int cacheCount = tempos.length; int resolution = seq.getResolution(); long us = 0; long tick = 0; int newReadPos = 0; int i = 1; // walk through all tempo changes and add time for the respective blocks // to find the right tick if (micros > 0 && cacheCount > 0) { // this loop requires that the first tempo Event is at time 0 while (i < cacheCount) { long nextTime = us + ticks2microsec(ticks[i] - ticks[i - 1], tempos[i - 1], resolution); if (nextTime > micros) { break; } us = nextTime; i++; } tick = ticks[i - 1] + microsec2ticks(micros - us, tempos[i - 1], resolution); if (Printer.debug) Printer.debug("microsecond2tick(" + (micros / 1000)+") = "+tick+" ticks."); //if (Printer.debug) Printer.debug(" -> convert back = " + (tick2microsecond(seq, tick, null) / 1000)+" microseconds"); } cache.currTempo = tempos[i - 1]; return tick; }
Binary search for the event indexes of the track
Params:
  • tick – - tick number of index to be found in array
Returns:index in track which is on or after "tick". if no entries are found that follow after tick, track.size() is returned
/** * Binary search for the event indexes of the track * * @param tick - tick number of index to be found in array * @return index in track which is on or after "tick". * if no entries are found that follow after tick, track.size() is returned */
public static int tick2index(Track track, long tick) { int ret = 0; if (tick > 0) { int low = 0; int high = track.size() - 1; while (low < high) { // take the middle event as estimate ret = (low + high) >> 1; // tick of estimate long t = track.get(ret).getTick(); if (t == tick) { break; } else if (t < tick) { // estimate too low if (low == high - 1) { // "or after tick" ret++; break; } low = ret; } else { // if (t>tick) // estimate too high high = ret; } } } return ret; } public static final class TempoCache { long[] ticks; int[] tempos; // in MPQ // index in ticks/tempos at the snapshot int snapshotIndex = 0; // microsecond at the snapshot int snapshotMicro = 0; int currTempo; // MPQ, used as return value for microsecond2tick private boolean firstTempoIsFake = false; public TempoCache() { // just some defaults, to prevents weird stuff ticks = new long[1]; tempos = new int[1]; tempos[0] = DEFAULT_TEMPO_MPQ; snapshotIndex = 0; snapshotMicro = 0; } public TempoCache(Sequence seq) { this(); refresh(seq); } public synchronized void refresh(Sequence seq) { ArrayList list = new ArrayList(); Track[] tracks = seq.getTracks(); if (tracks.length > 0) { // tempo events only occur in track 0 Track track = tracks[0]; int c = track.size(); for (int i = 0; i < c; i++) { MidiEvent ev = track.get(i); MidiMessage msg = ev.getMessage(); if (isMetaTempo(msg)) { // found a tempo event. Add it to the list list.add(ev); } } } int size = list.size() + 1; firstTempoIsFake = true; if ((size > 1) && (((MidiEvent) list.get(0)).getTick() == 0)) { // do not need to add an initial tempo event at the beginning size--; firstTempoIsFake = false; } ticks = new long[size]; tempos = new int[size]; int e = 0; if (firstTempoIsFake) { // add tempo 120 at beginning ticks[0] = 0; tempos[0] = DEFAULT_TEMPO_MPQ; e++; } for (int i = 0; i < list.size(); i++, e++) { MidiEvent evt = (MidiEvent) list.get(i); ticks[e] = evt.getTick(); tempos[e] = getTempoMPQ(evt.getMessage()); } snapshotIndex = 0; snapshotMicro = 0; } public int getCurrTempoMPQ() { return currTempo; } float getTempoMPQAt(long tick) { return getTempoMPQAt(tick, -1.0f); } synchronized float getTempoMPQAt(long tick, float startTempoMPQ) { for (int i = 0; i < ticks.length; i++) { if (ticks[i] > tick) { if (i > 0) i--; if (startTempoMPQ > 0 && i == 0 && firstTempoIsFake) { return startTempoMPQ; } return (float) tempos[i]; } } return tempos[tempos.length - 1]; } } }