Sound-effect descriptor table Confirmed

At a glance

In the game

Every UI, field-script and battle sound effect that is not a voice clip or music

Where

SCUS_942.54 rodata at RAM 0x8006F198 (file offset 0x5F998); no magic

Size / stride

100 rows × 8 bytes, ids 0x00..=0x63; ids ≥ 0x200 come from the current sound bundle instead

Parser

legaia_asset::sfx_table; CLI asset sfx-table <SCUS> [--json]; engine legaia_engine_audio::SfxBank + sfx_ring

Confidence

Confirmed - disc table parses identically to live RAM; bank routing pinned by the initialiser's own writes and byte matches against the extracted VABs (how we know)

Used by

audio stack, move-power cue path, field menu, media browser cue player

Record layout

A cue id indexes the table at an 8-byte stride. The field names are the designer's own, recovered from a runtime debug format string (p / t / l / n / id).

Which bank a cue plays from

Four fixed banks are open at once and each category keys exactly one of them. The other open slots hold variable banks (scene music, side-band, monster sounds) that no descriptor keys - "the SFX bank is the scene's music VAB" is true only of slot 1.

Raw TOC indices run two above extraction indices (CDNAME numbering); CDNAME labels read battle_data for 0868 and monster_data for 0869 - a label is a hint, the byte match is the verdict.

Slots share sound RAM in pairs

The field bank (slot 6) and the class-2 battle bank (slot 2) occupy the same physical SPU region, refilled per mode, so they are never resident together. Field modes open slots 0, 1, 3, 6; battle opens 0, 1, 2, 7. The battle mode init closes slot 6 and clears the field-bank latch 0x8007BAFC (so do the minigame warp and field-VM op 0x36 sub 3); the next field init sees the latch clear and reloads PROT 0876. A cue whose slot is closed is skipped, not rerouted.

The sizes are allocation, not enforcement: PROT 0869 overruns the region below slot 3 by 3 808 bytes whenever that slot is closed.

Firing a cue

Two readers consume the table: the per-actor trigger (used by the actor tick) and the per-frame cue ring drainer. The SPU programming under them is PlayStation library code; what is portable is the data and the ring.

The ring: four scheduled one-shots

• Four slots, each an i16 cue id plus a u32 countdown in vsyncs. A producer writes the id with timer 0 into a round-robin cursor slot; a fifth pending cue replaces one.
• An ager decrements every timer by the adaptive frame step and floors at zero; a slot at zero with no id becomes -1.
• The drainer plays a slot only when its timer is exactly zero and its id is still ≥ 0. A cue armed with timer N plays on the frame the countdown first reads zero.
• The ring value is the descriptor index; overlays that write the ring directly write ids as-is. The move-power cue path stores id - 1 for id < 0x40.

Voice allocation

The mixer record's enable byte (+0xB) skips a cue before any voice work; while a global override is set every cue is forced onto channel 6.

What a port has to get right

• Tone by index. The fire path hands the descriptor's tone index straight to the voice programmer. Several retail cues carry a note outside their tone's key window (menu cancel 0x37: tone 5, note 64, window [65,65]), so a key-range lookup renders silence. Engine: VabBank::play_tone beside the sequencer's play_note.
• UI cues are pitched down on purpose. Program 0 of the UI banks is a one-VAG-per-semitone key map whose center bytes sit 12..26 semitones above the descriptors' notes. Pitch is 0x1000 × 2^((note - center + fine/128)/12) with no sample-rate factor; a port that also multiplies by 22050/44100 drops another octave.
• The UI ids are global. Confirm / cursor / buzz / cancel are written by the SCUS list kernel that pages every pause-menu window; the Baka Fighter overlay is a co-user, not their source.
• There is no footstep sound. A probe over every producer, the trigger, the voice programmer and the ring sees nothing fire while walking; the only walk cues (0x2E, 0x2F) come from field-script triggers. A port that wants a footstep has to author one.
• Stage the right bank. A single-bank port fails quietly: a category-0 id fired through the class-2 bank resolves to a sibling sample - a genuine retail blip, twice as long and a fifth lower.

id <  0x200:  desc = table + id*8                       ; this page
id >= 0x200:  desc = bundle + offsets[0] + (id - 0x200)*8 ; current sound bundle, record 0

How we know

Parser: SfxTable::from_scus resolves the table from a SCUS_942.54 image; from_table_bytes parses a RAM window. The routing law lives beside it (slot_for_category, prot_index_for_slot, spu_base_for_slot, SLOT_ALIASES). Source of record: docs/formats/sfx-table.md.

See also