/// <summary>
/// Returns the exact tick at the time within a MIDI track.
/// </summary>
/// <param name="track">The MIDI track</param>
/// <param name="time">The time in microseconds.</param>
/// <param name="microsecondsPerTick">The microSeconds per tick of the MIDI file.</param>
/// <returns></returns>
private int microsecondsToTicks(MidiTrack track, double time, double microsecondsPerTick)
{
ushort division = (ushort)this.music.DeltaTimeSpec;
double currentTempo = MidiUtil.MIDI_DEFAULT_TEMPO;
int passedTicks = 0;
double passedMicroSeconds = 0d;
foreach (MidiMessage midiMessage in track.Messages)
{
passedMicroSeconds += midiMessage.DeltaTime * microsecondsPerTick;
passedTicks += midiMessage.DeltaTime;
MidiEvent midiEvent = midiMessage.Event;
if (passedMicroSeconds > time)
{
// if we overstepped the set time get the time between this message and the previous one
double prevMsgTime = passedMicroSeconds - midiMessage.DeltaTime * microsecondsPerTick;
return((int)((time - prevMsgTime) / microsecondsPerTick));
}
if (midiEvent.EventType == MidiEvent.Meta && midiEvent.MetaType == MidiMetaType.Tempo)
{
currentTempo = MidiMetaType.GetTempo(midiEvent.Data);
microsecondsPerTick = currentTempo / division;
}
}
return(passedTicks);
}
/// <summary>
/// Get the MIDI's duration in microseconds.
/// </summary>
public double GetDurationInMicroseconds()
{
double microsecondsPerTick = this.getMicrosecondsPerTick();
ushort division = (ushort)this.music.DeltaTimeSpec;
double currentTempo = MidiUtil.MIDI_DEFAULT_TEMPO;
double midiMusicTimeLength = 0d;
foreach (MidiTrack midiTrack in this.music.Tracks)
{
double trackTimeLength = 0d;
foreach (MidiMessage midiMessage in midiTrack.Messages)
{
trackTimeLength += midiMessage.DeltaTime * microsecondsPerTick;
MidiEvent midiEvent = midiMessage.Event;
if (midiEvent.EventType == MidiEvent.Meta && midiEvent.MetaType == MidiMetaType.Tempo)
{
currentTempo = MidiMetaType.GetTempo(midiEvent.Data);
microsecondsPerTick = currentTempo / division;
}
}
if (trackTimeLength > midiMusicTimeLength)
{
midiMusicTimeLength = trackTimeLength;
}
}
return(midiMusicTimeLength);
}
public void GetTempo()
{
Assert.AreEqual(500000, MidiMetaType.GetTempo(new byte[] { 7, 0xA1, 0x20 }, 0), "500000");
}
private double GetTimeLengthInMicroseconds(MidiMusic midiMusic)
{
ushort division = (ushort)midiMusic.DeltaTimeSpec;
const double defaultTempo = 500000; // in microseconds per quarter-note, equals 120 beats per minute => 500000 / 1000000 * 4 * 60 = 120
double currentTempo = defaultTempo;
double microsecondsPerTick = 0d;
// division = 59512;
Debug.Log("Divisions: " + System.Convert.ToString(division, 2).PadLeft(16, '0'));
if (division >> 15 == 0)
{
Debug.Log("MSB is 0");
microsecondsPerTick = currentTempo / division;
// Debug.Log("MicrosecondsPerTick: " + microsecondsPerTick);
}
else
{
Debug.Log("MSB is 1");
byte bitmask = 255; // 1111_1111
byte bits = (byte)((division >> 8) & bitmask);
byte negatedFramesPerSecond = (byte)~bits;
byte framesPerSecond = (byte)(negatedFramesPerSecond + 1);
Debug.Log("framesPerSecond: " + framesPerSecond);
byte ticksPerFrame = (byte)(division & bitmask);
Debug.Log("ticksPerFrame: " + System.Convert.ToString(ticksPerFrame, 2));
Debug.Log("ticksPerFrame: " + ticksPerFrame);
double ticksPerSecond = ticksPerFrame * framesPerSecond;
microsecondsPerTick = 1000000 / ticksPerSecond;
}
double midiMusicTimeLength = 0d;
foreach (MidiTrack midiTrack in midiMusic.Tracks)
{
double trackTimeLength = 0d;
foreach (MidiMessage midiMessage in midiTrack.Messages)
{
trackTimeLength += midiMessage.DeltaTime * microsecondsPerTick;
MidiEvent midiEvent = midiMessage.Event;
if (midiEvent.EventType == MidiEvent.Meta && midiEvent.MetaType == MidiMetaType.Tempo)
{
currentTempo = MidiMetaType.GetTempo(midiEvent.Data);
microsecondsPerTick = currentTempo / division;
}
}
if (trackTimeLength > midiMusicTimeLength)
{
midiMusicTimeLength = trackTimeLength;
}
}
return(midiMusicTimeLength);
}
