Defined in [macros/scripts/audio.asm](https://github.com/pret/pokecrystal/blob/master/macros/scripts/audio.asm) and [audio/engine.asm:MusicCommands](https://github.com/pret/pokecrystal/blob/master/audio/engine.asm).
(Used in channels 1-4) (When using in channel 4, the *intensity* byte is not needed)
Sets the length multiplier of notes on the channel, and the envelope for channels 1-3 (see `intensity`).
The first byte only reads the lower 4 bits, and multiplies it by the note length. A larger number means slower playback/longer notes. `$C` is commonly used for a normal timeframe.
The second byte is identical to the first byte in the `intensity` command.
(Used on channels 1-3) (Used to set instrument on channel 3)
For channels 1&2:
This sets the volume and fade of the notes. The high nibble is the starting volume, 0 is mute, $F is max. Bit 3 determines the fade direction (0=Fade to silence, 1=Fade to max volume). The last 3 bits is how fast the fade happens. 0 is no fade, 1 is fastest fade, 7 is slowest fade.
For channel 3:
The high nibble sets the volume of channel 3. Only 4 values are accepted (0=Mute, 1=100% volume, 2=50% volume, 3=25% volume). The low nibble sets the instrument/waveform for channel 3 to play. Crystal natively has 10 instruments, values 0-9.
This bends the pitch of the note played next, and only that note.
The first byte tells how many frames to play the destination note for, before the length of the note is up.
The high nibble of the second byte is the octave of the destination note.
The low nibble of the second byte is the destination note. If rest is used as the destination note, then the whole destination pitch becomes `$0000` (the lowest pitch).
Modifies pitch after the timer runs out, making notes sound less "flat".
First byte will set the delay, decrementing by one each frame. When it tries subtracting from 0, it starts decrementing from the speed timer.
Second byte, high nibble is the speed timer. It will decrement by one each frame, when it tries decrementing from 0, it mods the frequencey by half of pitch depth, and resets itself to it's initial value.
Second byte, low nibble is the pitch depth. Half of this value will alternate between adding to the pitch, and subtracting from the pitch each time speed timer resets. When this is an odd number, the value added to the pitch will be greater than the value subtracted from the pitch.
Ex: normal pitch of 405, if pitch depth = 3, it will alternate between 407 and 404. Speed timer does NOT reset when a new note is played. only when the song stops or changes. (Also, because a timer counts 0, a timer of 5 will take 6 frames to change.)
