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diff --git a/doc/eif.txt b/doc/eif.txt new file mode 100644 index 0000000..3d1f27d --- /dev/null +++ b/doc/eif.txt @@ -0,0 +1,27 @@ +============================================================================= + +OVERVIEW + + EIF stands for "Echo Instrument Format" and it's the format in which FM + instruments are stored. + +FORMAT + + EIF instruments are essentially raw dumps of the YM2612 registers. They + consist of 29 bytes, where each byte belongs to a different YM2612 + register. The registers are stored in the following order (assuming the + first FM channel): + + $B4 -- Algorithm and feedback + $30, $34, $38, $3C -- Multiplier and detune + $40, $44, $48, $4C -- Total level + $50, $54, $58, $5C -- Attack rate + $60, $64, $68, $6C -- Decay rate + $70, $74, $78, $7C -- Sustain rate + $80, $84, $88, $8C -- Release rate and sustain level + $90, $94, $98, $9C -- SSG-EG + + Some bits are unused and ignored by the YM2612. In an EIF instrument, + they *must* be 0, since Echo will rely on this for optimization purposes. + +============================================================================= |