VAB sound bank Confirmed

Every instrument you hear in Legaia's music - the strings under the world map, the drums in a battle theme - and every sound effect is a sampled sound stored in a VAB bank. A VAB is Sony's standard PlayStation instrument bank: a set of programs (instruments) made of tones (key-range variants) that point into compressed sample bodies the sound chip plays. The bank is one half of the music; the note data that plays against it is the other half, the SEQ.

At a glance

Magic: VABp at the bank's own offset 0 - usually not the PROT entry's offset 0 (see the wrapper figure)
Where on disc: 424 banks across 219 PROT.DAT entries. The vab_01 cluster (extraction 1072..1194) holds one bank per entry; 0891_level_up is the single multi-bank archive (206 banks); most music banks ride inside scene streaming containers
Stride: 32-byte header, 16-byte program slots, 32-byte tones, 8-byte-unit sample sizes
Parser: crates/vab (header + extractor + SPU-ADPCM decoder); playback side engine-audio::VabBank
Confidence: Confirmed - standard Sony layout; the Legaia-specific rules are pinned by the bank-open and program-change routines (how we know) and disc-wide corpus tests
Used by: Audio stack, Media player, Asset viewer

What trips up a stock VAB reader

The format itself is documented in the PsyQ SDK, so this page covers only the parts that are Legaia-specific - the things that make a generic VAB extractor return nonsense on this disc.

The bank is usually wrapped. The dominant carrier is the scene streaming shape: a 4-byte chunk header, the VAB body, a second chunk header, then the SEQ. crates/vab::parse_header(buf, offset) takes a starting offset for that reason.
Don't trust the filename. Extraction labels carry the +2 CDNAME numbering shift; a block name is a hint. Trust the VABp magic and the loader constant.
Program numbers are not tone-page indices. Tone pages are packed by used program, so a program finds its page by rank. This is the single most consequential fact on this page.
The VAG size table is 1-indexed. Slot 0 is a spacer, 0 in every retail bank; it is not a pitch or sample-rate field.
Sample rate lives in center. A 22.05 kHz body is authored with its center key an octave high. A port that also scales by 22050/44100 plays everything an octave low.

Most retail BGM is a wrapped pair - bank first, sequence second - inside a scene's streaming entry. SceneAssets::seq_in_stream_entries and bgm_seq_offset slice past the wrappers.

Layout

A bank is a fixed 32-byte header, a 128-slot program table, a packed run of 16-tone pages, a 256-entry sample-size table, and then the sample bodies.

Offset Size Field Meaning

+0x00 4 magic VABp

+0x04 u32 version Bank format version

+0x08 u32 id Bank id

+0x0C u32 size Whole-bank byte size

+0x12 u16 ps Number of used programs = number of tone pages that follow

+0x14 u16 ts Total tone count

+0x16 u16 vs Number of VAG sample bodies

+0x18 u8 × 4 master vol / pan, attr Bank-wide mix defaults

+0x20 128 × 16 ProgAtr[128] One slot per program number: tones byte, vol, pan, and reserved words retail reuses at open time

+0x820 ps × 16 × 32 VagAtr pages Packed: one 16-tone page per used program, in slot order

after pages 256 × u16 vag_size[] 1-indexed sizes in 8-byte units; [0] is the spacer

after table - VAG bodies SPU-ADPCM sample data, back to back

Offset	Size	Field	Meaning
`+0x00`	4	`magic`	`VABp`
`+0x04`	u32	`version`	Bank format version
`+0x08`	u32	`id`	Bank id
`+0x0C`	u32	`size`	Whole-bank byte size
`+0x12`	u16	`ps`	Number of used programs = number of tone pages that follow
`+0x14`	u16	`ts`	Total tone count
`+0x16`	u16	`vs`	Number of VAG sample bodies
`+0x18`	u8 × 4	master vol / pan, attr	Bank-wide mix defaults
`+0x20`	128 × 16	`ProgAtr[128]`	One slot per program number: `tones` byte, vol, pan, and reserved words retail reuses at open time
`+0x820`	`ps` × 16 × 32	`VagAtr` pages	Packed: one 16-tone page per used program, in slot order
after pages	256 × u16	`vag_size[]`	1-indexed sizes in 8-byte units; `[0]` is the spacer
after table	-	VAG bodies	SPU-ADPCM sample data, back to back

Program slots vs packed tone pages

A SEQ ProgramChange (or an SFX descriptor) names a program number, which indexes the 128-slot ProgAtr table directly. The tone pages that follow are packed: one 16-tone page per program whose tones byte is non-zero, ps pages in total, in slot order. A program finds its page by its rank among the used slots, not by its own number.

Retail builds the rank map once, at bank open: the open routine writes the running used-program count into each slot's +8 reserved word, and the program-change handler reads it back as the page index (how we know).
The open also stashes each VAG's SPU address >> 3 into the +0xC / +0xE reserved slots.
66 of the 218 wrapped banks - 43 of the 77 music_01 banks - use sparse program sets, so indexing pages by the raw program number mis-tones or silently drops most of their instruments.
The engine expands pages into slot space at upload (VabBank::upload).

The unused-slot alias

Retail stores the rank counter before the used check increments it, so a program-change to an unused slot borrows the next used slot's page while keeping its own mvol/mpan. Real BGM exercises this - music_01 PROT 868 program 5 and PROT 996 program 19 select gap slots that play through the alias - and the engine reproduces it (real_seq_program_change_coverage.rs pins the census). A change past the last used slot reads garbage beyond the tone region in retail; the engine leaves those voices silent.

Tone attributes: which fields retail uses

Each 32-byte tone (VagAtr) carries the standard Sony fields. A disc-wide census of every tone fixes which of them the retail data populates:

Field	Role in playback	Retail data
`vol` / `pan`	Per-tone mix	Used
`center` / `shift`	Key to pitch - the whole of it, sample rate included	Used
`min` / `max`	Note range that selects the tone	Used
`adsr1` / `adsr2`	Envelope	Used
`pbmin` / `pbmax`	Pitch-bend range in semitones; the sequencer scales a `0xEn` wheel event by the sounding tone's range (`VabBank::pitch_bend_range`)	Mostly 2 (GM default); a few tones at 4 / 12 / 24 / 40; `(0, 0)` does not bend
`vibw` / `vibt`	Vibrato	Always zero - no LFO needed
`porw` / `port`	Portamento	Always zero

`center` / `shift` carry the sample rate

center is the key at which the tone plays at unity - SPU pitch 0x1000, 44.1 kHz - and shift raises it by shift/128 of a semitone. The header has no per-sample rate, so a 22.05 kHz body is authored with center twelve semitones above the key it should sound at. Full key-on law: audio § key-on pitch law. crates/vab's WAV writer hard-codes 22050 for standalone extraction, a separate question from playback.

The VAG size table is 1-indexed

The trailing table is 256 × u16; vag_table[1..=vs] hold each sample's size in 8-byte units, so vag_table[0] is a leading spacer. It is 0 in all 424 retail banks, and no pitch offset is derived from it - VabReport::vag_table_spacer surfaces the raw byte only.

History: the "three multi-bank archives" and the 1191-header count

Counts of 1191 VABp headers across 239 entries, with 0889 / 0890_sound_data2 as multi-bank archives, came from the superseded over-read entry window (prot § History), which spans those two small entries into 0891's 6 MB archive. On their own sectors they hold one and zero banks; exactly one multi-bank archive exists. See do-not-re-walk.

How we know

Function / test	Address	What it proves	Source
`SsVabOpenHead`	`FUN_80068D94`	Rank map built at open into `ProgAtr+8`; VAG SPU address into `+0xC`/`+0xE`	`ghidra/scripts/funcs/80068d94.txt`
Program-change handler	`FUN_80068B98`	Reads the rank byte back as the tone-page index; the unused-slot alias	`ghidra/scripts/funcs/80068b98.txt`
`real_vab_program_mapping`	-	Sparse program sets across the corpus; slot-space expansion is required	`crates/engine-audio/tests/` (disc-gated)
`real_vab_tone_attributes`	-	Which tone fields retail populates; vibrato / portamento always zero	`crates/engine-audio/tests/` (disc-gated)
`corpus_vag_spacer`	-	`vag_table[0] == 0` in 424 / 424 banks	`crates/vab/tests/` (disc-gated)
`real_seq_program_change_coverage`	-	Census of program changes that hit unused slots in real BGM	`crates/engine-audio/tests/` (disc-gated)

Full spec with every field: docs/formats/vab.md.

API

use legaia_vab::parse_header;
let header = parse_header(buf, offset)?;
println!("VAB v{} ps={} ts={}", header.version, header.ps, header.ts);

For bulk extraction of every VAB and per-program WAV files, see the vab CLI in extraction tooling. The decoder shares its F0/F1 filter constants with crates/xa.