SYN file format: SimSynth patch

Introduction

A .syn file is a patch of SimSynth, the subtractive synthesizer that came with FruityLoops, now FL Studio: the settings of three oscillators, an LFO, envelopes, a filter and an amplifier, and in the newer version a short riff and a comment. The synthesizer was followed by SimSynth 2 and by SimSynth Live in FL Studio, and the patch file grew with it. FruityLoops 3 ships its patches in folders such as SS_Instruments, SS2_Effects and SS2_Riffs.

Every file is one fixed structure with no sections or lengths, and its size tells the version: 989 bytes for version 1 and 6,763 bytes for version 2. Image-Line has not published the format. These pages work it out from the loader in ss2wav.dll, the patch renderer that ships with FruityLoops 3 and FL Studio 5, and from the real patch files on this machine (352 different ones, all read without a problem), and mark each field that is a guess.

Other programs use the same extension for their own files. The only one on the machine this was written on was the info.syn text file of the DOS game Stunts. A SimSynth patch is told by its first five bytes, the characters SYNTH, then a version word and its exact length.

A patch dropped on any page opens in the explorer, with its oscillators, envelope points and comment, and every field in the order of its bytes.

Variations

Format	Variation	About	Open
`.SYN`	SimSynth patch, version 1	989-byte patches of the first SimSynth, with five-point envelopes.	Open
`.SYN`	SimSynth patch, version 2	6,763-byte patches of SimSynth 2 and SimSynth Live, with envelopes, a riff and a comment.	Open

SimSynth patch, version 1

The patch of the first SimSynth: four records of 220 bytes (three oscillators and the LFO), three envelopes of five points and 17 words of settings, 989 bytes in all. There is no riff and no comment.

The file starts with SYNTH and the word 1, and is exactly 989 bytes.

SimSynth patch, version 2

The patch of SimSynth 2 and SimSynth Live: four records of 286 bytes, three envelopes of up to 300 points, two blocks of settings, a riff of 520 words and a 512-byte comment, 6,763 bytes in all. A revision number in the header (4 to 17 are seen) lets the loader bring older patches up to date.

The file starts with SYNTH and the word 2, and is 6,763 bytes long.

Telling them apart

The explorer reads the first five bytes, then the word at offset 5, and the file size. SYNTH with a 1 and 989 bytes is version 1; SYNTH with a 2 and 6,763 bytes is version 2. Anything else with the extension is not a SimSynth patch.

Not described

This page is partial: Image-Line has not published the format, and the detail is on the two version pages.

Reference: the meaning of most fields in both versions is inferred or unknown, the version 1 loader was not read, and other programs’ .syn files are not described.
Viewer: it shows the fields as numbers, lists envelope points without drawing them, shows the riff and most settings as unnamed words, and does not open the wave files the patches name.

.SYN File Format