TFI and VGI formats
Type: FM instrument
TFI and VGI are the FM instrument formats for TFM Maker and VGI Maker, respectively. The two are very similar and while rarely used directly by sound drivers, they're easier to parse for instrument editors (as every argument is in its own byte).
Since they're so close, we're documenting both here.
TFI (TFM Maker format)
TFM Maker instruments have the ".tfi" file extension and
consist of 42 bytes. The first two bytes are:
| Size | Description | Range |
|---|---|---|
| 1 byte | Algorithm | 0 to 7 |
| 1 byte | Feedback | 0 to 7 |
The following 40 bytes are for the operators, with each group of 10 bytes being an operator. Operators come in S1, S3, S2, S4 order. These bytes are as follows (repeat for each operator):
| Size | Description | Range |
|---|---|---|
| 1 byte | Multiplier | 0 to 15 |
| 1 byte | Detune | 0 to 6 |
| 1 byte | Total level | 0 to 127 |
| 1 byte | Rate scaling | 0 to 3 |
| 1 byte | Attack rate | 0 to 31 |
| 1 byte | Decay rate | 0 to 31 |
| 1 byte | Sustain rate | 0 to 31 |
| 1 byte | Release rate | 0 to 15 |
| 1 byte | Sustain level | 0 to 15 |
| 1 byte | SSG-EG | 0 to 15 |
All values use the same format as the corresponding YM2612 registers, except for detune. In order to get the detune, substract 3 (to put it in the -3 to +3 range), then convert that to the format the YM2612 wants.
VGI (VGM Maker format)
VGM Maker instruments have the ".vgi" file extension and
consist of 43 bytes. It's almost identical to TFI files, except that an
extra byte follows feedback, which includes FMS and AMS (in the same
format as register $B4+
from the YM2612).