// util functions
private static bool TrackIsOmitable(MidiTrack tr)
{
foreach (MidiEvent ev in tr.midiEvents)
{
if (ev is MetaMidiEvent)
{
MetaMidiEvent mev = ev as MetaMidiEvent;
if (mev.getMetaType() == MetaType.TempoSetting)
{
return(false);
}
else if (mev.getMetaType() == MetaType.TimeSignature)
{
return(false);
}
else if (mev.getMetaType() == MetaType.MarkerText)
{
return(false);
}
}
else if (ev is MessageMidiEvent)
{
MessageMidiEvent mev = ev as MessageMidiEvent;
if (mev.type == NormalType.NoteON)
{
return(false);
}
if (mev.type == NormalType.NoteOFF)
{
return(false);
}
}
}
return(true);
}
public static void QuantizeTempo(MidiFile midi)
{
/******************
* Rounds Tempo Events to the nearest BPM integer
*/
foreach (MidiTrack trk in midi.midiTracks)
{
for (int i = 0; i < trk.midiEvents.Count; i++)
{
MidiEvent ev = trk.midiEvents[i];
if (ev is MetaMidiEvent)
{
MetaMidiEvent mev = ev as MetaMidiEvent;
if (mev.getMetaType() == MetaType.TempoSetting)
{
byte[] tempoBytes = mev.getEventData();
Debug.Assert(tempoBytes.Length == 6);
int us = (tempoBytes[3] << 16) | (tempoBytes[4] << 8) | tempoBytes[5];
double bpm = CalcBPM(us);
double ibpm = Math.Round(bpm, MidpointRounding.AwayFromZero);
int ius = CalcUsPerBeat(ibpm);
byte[] newTempoBytes = new byte[3];
newTempoBytes[0] = (byte)(ius >> 16);
newTempoBytes[1] = (byte)((ius >> 8) & 0xFF);
newTempoBytes[2] = (byte)(ius & 0xFF);
MetaMidiEvent newTempoEvent = new MetaMidiEvent(mev.absoluteTicks, 0x51, newTempoBytes);
trk.midiEvents[i] = newTempoEvent;
}
}
}
}
}
public static void Trim(MidiFile midi)
{
/******************
* removes empty tracks and redundant controller/voice events
*/
midi.midiTracks.RemoveAll(TrackIsOmitable);
foreach (MidiTrack tr in midi.midiTracks)
{
// int array for storing the last set values of the controller values
int[] controllerValues = new int[128];
for (int i = 0; i < controllerValues.Length; i++)
{
controllerValues[i] = -1;
}
int lastVoice = -1;
int lastPitchBendA = -1;
int lastPitchBendB = -1;
int lastTempo = -1;
for (int i = 0; i < tr.midiEvents.Count;)
{
if (tr.midiEvents[i] is MessageMidiEvent)
{
MessageMidiEvent mev = tr.midiEvents[i] as MessageMidiEvent;
if (mev.type == NormalType.Program)
{
if (mev.parameter1 == lastVoice)
{
tr.midiEvents.RemoveAt(i);
continue;
}
lastVoice = mev.parameter1;
}
else if (mev.type == NormalType.PitchBend)
{
if (mev.parameter1 == lastPitchBendA && mev.parameter2 == lastPitchBendB)
{
tr.midiEvents.RemoveAt(i);
continue;
}
lastPitchBendA = mev.parameter1;
lastPitchBendB = mev.parameter2;
}
else if (mev.type == NormalType.Controller)
{
if (controllerValues[mev.parameter1] == mev.parameter2)
{
tr.midiEvents.RemoveAt(i);
continue;
}
controllerValues[mev.parameter1] = mev.parameter2;
}
}
else if (tr.midiEvents[i] is MetaMidiEvent)
{
MetaMidiEvent mev = tr.midiEvents[i] as MetaMidiEvent;
if (mev.getMetaType() == MetaType.TempoSetting)
{
byte[] tempoBytes = mev.getEventData();
Debug.Assert(tempoBytes.Length == 6);
int us = (tempoBytes[3] << 16) | (tempoBytes[4] << 8) | tempoBytes[5];
if (lastTempo == us)
{
tr.midiEvents.RemoveAt(i);
continue;
}
lastTempo = us;
}
}
// only count up if the current event didn't get deleted
i++;
}
}
}
