Note: Everything here is in Little-endian byte-order
The GF1 Patch files are multipart sound files for the Gravis Ultrasound
sound card to emulate MIDI sounds in high quality. Each Patch can consist
of many samples (for example, a string ensemble consists of Violin, Viola,
Cello, Bass) which are played depending on the note to play. A patch can also
contain a part to be played before the loop and a part to be played after
the tone has been released.
OFFSET Count TYPE Description
0000h 12 char ID='GF1PATCH110'
000Ch 10 char Manufacturer ID
0018h 60 char Description of the contained Instruments
or copyright of manufacturer.
0054h 1 byte Number of instruments in this patch
0055h 1 byte Number of voices for sample
0056h 1 byte Number of output channels
(1=mono,2=stereo)
0057h 1 word Number of waveforms
0059h 1 word Master volume for all samples
005Bh 1 dword Size of the following data
0060h 36 byte reserved
Following this header, the instruments with their headers follow.
An instrument header contains the name and other data about one
instrument contained within the patch.
OFFSET Count TYPE Description
0000h 1 word Instrument number. ?Maybe the MIDI instrument
number?. In the Gravis patches, this is 0, in
other patches, I found random values.
0002h 16 char ASCII name of the instrument.
0012h 1 dword Size of the whole instrument in bytes.
0016h 1 byte Layers. Needed for whatever.
0017h 40 byte reserved
About the patch, I don't know anything. Maybe somebody could enlighten me.
Each patch record has the following format :
OFFSET Count TYPE Description
0000h 7 char Wave file name
0007h 1 byte Fractions
0008h 1 dword Wave size.
Size of the wave digital data
000Ch 1 dword Start of wave loop
0010h 1 dword End of wave loop
0012h 1 word Sample rate of the wave
0014h 1 word Minimum frequency to play the wave
0016h 1 word Maximum frequency to play the wave
0018h 1 dword Original sample rate of the wave data
001Ch 1 int Fine tune value for the wave
001Eh 1 byte Stereo balance, values unknown**
001Fh 6 byte Filter envelope rate
0025h 6 byte Filter envelope offse
002Bh 1 byte Tremolo sweep
002Ch 1 byte Tremolo rate
002Dh 1 byte Tremolo depth
002Fh 1 byte Vibrato sweep
0030h 1 byte Vibrato rate
0031h 1 byte Vibrato depth
0032h 1 byte Wave data, bitmapped
0 - 8/16 bit wave data
1 - signed/unsigned data
2 - de/enable looping
3 - no/has bidirectional looping
4 - loop forward/backward
5 - Turn envelope sustaining off/on
6 - Dis/Enable filter envelope
7 - reserved
0033h 1 int Frequency scale, whatever that means
0035h 1 word Frequency scale factor
0037h 36 byte Reserved