EEF format
Type: PSG instrument
EEF ("Echo Envelope Format") is a format for PSG instruments introduced
by Echo. The
suggested file extension of ".eef".
Every byte represents one tick (1/60th second), with the following format:
- Lower nibble is the volume (0 = peak, 15 = mute).
- Higher nibble is a pitch shift (see table below).
In addition two values are used to indicate the loop points:
$FE indicates where the loop starts, $FF
indicate where the loop ends (and the end of the instrument).
Loop points are required, if you don't want an
instrument to loop then make a single-value loop point (if you want
it to go mute, use $FE $0F $FF at the end).
The pitch shift is relative to the nominal pitch of the channel (i.e. what note is intended to be played). The higher nibble can be one of the following values:
| Value | Shift |
|---|---|
$0x | Intact |
$1x | +1 semitone |
$2x | +2 semitones |
$3x | +3 semitones |
$4x | +4 semitones |
$5x | +6 semitones |
$6x | +8 semitones |
$7x | +12 semitones |
$8x | -1 semitone |
$9x | -2 semitones |
$Ax | -3 semitones |
$Bx | -4 semitones |
$Cx | -6 semitones |
$Dx | -8 semitones |
$Ex | -12 semitones |
Values $F0 to $FD are not valid in the
current version.