private void AddMIDICommand(MIDICommandType type, int channel, int note, int velocity)
{
// Each of the three MIDI commands supported by VRChat is composed of three bytes.
// The first four bits of the first byte determine the command type (NoteOn/NoteOff/ControlChange).
// The last four bits of the first byte determine the channel (instrument) the command is targeting.
// The second byte's 7 primary bits determine the note to be played.
// The last byte's 7 primary bits detemrine the velocity of the command.
if (currentOffset > buffer.Length - MIDI_BYTES_PER_COMMAND)
{
throw new InvalidOperationException("MIDICommandChunk is full");
}
switch (type)
{
case MIDICommandType.NoteOff:
buffer[currentOffset] = 0x80;
break;
case MIDICommandType.NoteOn:
buffer[currentOffset] = 0x90;
break;
case MIDICommandType.ControlChange:
buffer[currentOffset] = 0xB0;
break;
}
buffer[currentOffset++] |= (byte)channel;
buffer[currentOffset++] = (byte)note;
buffer[currentOffset++] = (byte)velocity;
}
private void Add(byte a, byte b, int extraBits = 0, MIDICommandType type = MIDICommandType.NoteOn)
{
// Since MIDI commands' note and velocity bytes only have 7 usable bits,
// the highest bits of each two bytes are moved into the lowest two bits
// of the MIDI channel.
int channelA = (a & 0x80) >> 7;
int channelB = (b & 0x80) >> 6;
int channelHigh = (extraBits & 0x3) << 2;
int channel = channelHigh | channelA | channelB;
AddMIDICommand(type, channel, a & 0x7F, b & 0x7F);
}
