GT4SoundTool

UNFINISHED

GT4 tool for conversion of music banks into midi/sound fonts.

Current state:

Can extract MIDIs out of .sqt (Sq table)
Can somewhat extract sound samples (vag format) from .ins (instrument) files into .sf2 sound banks
Can create .wav from a midi & sf2 (won't be too accurate, some parameters are missing & some things need to be fixed)
Again, the wav output is not currently accurate enough
Will NOT currently read SeSeq (sound effect "midi" sequences) embedded inside instrument files, but refer to this repo for structures (they are figured)

This repo should be considered as a small non-serious test project to research sound files, perhaps someone can pick up on it in the future.

The documentation is the code. I've documented my references as much as I could.

Documentation

There are two types of sequencers to keep in mind, Sq and Se, Sq for tracks, Se for sound effects.

Sq

Sq (file magic Ssqt & Sssq), used by .sqt files, is quite simply a midi file that can contain multiple sequences aka tracks. The format is nearly identical to the MIDI File Format.

SDDRV::SqSequencer::* handles these.

Ins (Instrument)

.ins (file magic INST) files are linked to those Sq's, providing the samples for each instrument (& their note ranges) used by each MIDI channel. Despite having SShd header within, these files does not follow the regular/general Sony SShd/SSbd header format normally used by .ads music formats.

Ins is also refered to as Jam, possibly directly referencing the sound authoring tool provided by the PS2 SDK (in PS2SDK/P-sound/atools/Sndtool111/mac/SoundPreview111/Doc/html/jam.htm - note: documentation is all in japanese).

Ins are also used standalone for sound effect banks where their MIDI sequences are directly bundled in, these are Se's, handled by SDDRV::SeSequencer::* with a different set of supported MIDI commands.

General structure (actual field layout omitted):

InsHeader - General Instrument Header (carsound files also uses this exact structure with a different magic for a totally different purpose)
- EsHeader
  - JamHeader
    - JamProgramChunk - Chunks holding programs for each midi channel (when ProgramChange is called) with details such as note range & more
      - JamSplitChunk - Chunk per note range with details such as note range, PS2 ADSR settings, volume, pan, lfo table index & more
    - VelocityChunk - Chunk holding note on velocity - velocities are indexed into this to get the real one
    - LfoTableChunk - Lfo Param Chunk
    - UnkChunk
    - SeSeqChunk - MIDI Sequences for the Se Sequencer (sound effects)
    - SeProgChunk - Holds programs for each midi channel for the Se Sequencer (sound effects)

Current State/Problems/Reverse-Engineering Notes

Currently, this tool takes .sqt files and spits out:

.mid - One MIDI sequence per track inside .sqt
.sf2 - One SoundFont2 per track with the instruments
.wav - A stereo wav conversion - just an attempt.
samples folder - Extracted samples from .ins, mono

The .wav is partially correct. But:

The pitch for certain notes is incorrect. This is caused by the fourth byte in JamSplitChunk not currently being used - forcing the game not to apply it confirms that the same overall incorrect pitch happens so this is a good sign
Some notes aren't held long enough. Not sure why.
Volume provided by JamSplitChunks isn't really accounted for yet
ADSR Envelope values in JamSplitChunk aren't accounted for yet, not sure how to interpret it. vgmtrans's PSXSPU.h might give a clue, but one of the issues mentions that not everything is inherently supported by .sf2.
Loops. ins holds sample data as the usual Sony .vag format which explicitly has loop data. I've tried to properly detect loops so that they can be written into the .sf2 properly, but samples don't quite loop properly yet.
Lack of reverb - Flag 0x80 within JamSplitChunk enables mixing/reverb, not sure how to handle it.
No LFO handling

As for reverse-engineering, the PS2's EE cannot interact directly with the sound chip so everything has to go through IOP first. While it is possible to use built-in libs that only lets you focus on EE code, the game does this pretty low level (using libsd).

It essentially goes like this internally:

-> Init SDDRV (Sequencers, Voice System, Es, etc). -> Start SPUP RPC Service (PDISPU2.irx) -> Open files i.e SDDRV::Jam::open -> Process reading sqt, etc. -> SDDRV::VoiceSystem::updateCore passes SPU structure containing sound parameters to IOP -> SPUP Rpc Cmd 4 to pass said structure -> [In IOP] sceSdSetAddr, sceSdSetParam, sceSdSetSwitch etc using structure.

Useful Tools/Docs

Midica - Playback of .mid + .sf2, seeing events
Polyphone - Debugging of .sf2
SF2 Specification
IDA
PS2 SDK Docs, like PS2 IOP Reference Sound, sdmacro.h, etc
IDA & Ghidra databases
010 Editor Templates - INST & SQT
The code for this tool will have more details.

Nenkai / GT4SoundTool