Sylpheed/docs/re/structures/sound-pak-contents.md

What is actually in sound.pak — and the language substitution

✅ Settled 2026-08-26. sound.pak's 9 519 entries are almost entirely accounted for: the Japanese voice set, the English voice set, and 35 music / jingle banks. The FILES record in tables.pak names the Japanese half, and the game reaches the English half by substituting the leading directory.

Until now the corpus described sound.pak as "~9 519 headerless entries, params in an unknown table". The table is sound-cue-table.md, and this page is the census.

The name is the key

Every path in FILES hashes straight into the sound.pak TOC with name_hash — 5 135 of 5 135, using the path exactly as stored (backslashes, case-insensitive):

jpn\etc\VOICE_D_257.slb  ->  name_hash  ->  TOC entry (offset, size)

No transformation, no prefix, no stem. Taking the basename instead resolves only 35 — precisely the 35 root-level BGM_* / JNGL_* banks whose basename is their path, which is the control that shows the full path is what matters.

This is not luck: the hash's low 24 bits are a residue mod 0x00FFF9D7 and the top byte is a byte-sum, so for 5 135 probes against 9 519 occupied slots the expected number of accidental hits is about 0.01.

The census

what	entries
jpn\… — named directly by FILES	5 100
eng\… — the same names with the directory substituted	4 382
BGM_*.slb, JNGL_*.slb at the root	35
static.slb and Pj_Silph.xgs — named by BANK_SE / SETTINGS	2
total accounted	9 519
TOC total	9 519

The archive is now fully accounted for. The last two took a correction: I first reported them as unidentified, having looked past the fact that the same IDXD object names them. BANK_SE's single field is Static.slb (8 970 240 bytes — the shared sound-effect bank) and SETTINGS.PARAM is Pj_Silph.xgs (533 bytes — the XACT global settings). Both hash into the TOC, and both were sitting in the table I had already printed at the top of this page. For 18 candidate names against 9 519 occupied slots the expected number of accidental matches is about 4 × 10⁻⁵, and these two are corroborated by being named in the table rather than guessed.

Only eng and jpn resolve. deu, fra, ita, esp and the alternative spellings fre/ger/spa produce zero hits, which is the measurement behind the claim that only two voice sets are shipped — the other four languages are subtitle-only.

718 of the 5 100 Japanese banks have no English counterpart. That is consistent with the previously recorded finding that a set of lines exists only undubbed, and it puts a number on it from the archive side.

❌ CORRECTED the same day — see slb-data-offset.md. The section below measures correctly but concludes wrongly. The Japanese banks are not a different layout: the leading-stream offset is first_riff % 2048, which is 1392 only in <lang>\etc\. Every "misaligned" row here is a bank being decoded mid-packet, in English as well as Japanese. The numbers stand as a measurement of the old constant's reach; the interpretation does not.

⚠️ The leading-region rule is English-only

This is the part that matters most, and it bounds an existing result.

voice-bank-leading-region.md established the hybrid layout: a bank may carry a leading headerless XMA1 region before its first RIFF, recognised by the first RIFF sitting exactly at 1392 + n·2048. That was derived from VOICE_D_450–454, and it reproduces exactly — all five, at 16 384 / 2 048 / 14 336 / 45 056 / 59 392 bytes, matching the recorded figures to the byte. The pipeline is sound.

But those five are eng\etc\ banks, and the rule does not generalise:

set	aligned	misaligned	no RIFF	first RIFF ≤ 1392
eng\… (4 382)	1 571	2 060	696	55
jpn\… (5 100)	0	4 301	799	—

Not one of the 5 100 Japanese banks satisfies the alignment condition. The rule describes a third of the English set and none of the Japanese set.

Being careful about what that does and does not mean: "misaligned" only means the leading-segment branch does not fire, and to_xma_riffs still walks the bank's sub-waves normally — so this is not evidence that those banks are broken. What it does mean is that the leading-region finding is a property of some English banks, not of .slb in general, and any code or documentation that treats it as the bank format is overreaching. The Japanese banks are laid out differently and that layout is not decoded.

How I nearly got this wrong

I first resolved the five documented banks through their FILES paths, which are jpn\etc\…, and got leading regions of 59 600 / — / 6 352 / 14 544 / 28 880 — none a multiple of 2 048, none matching the recorded figures. The tempting reading was that my extraction was broken. The alignment condition is what said otherwise: a broken reader would not produce exactly the recorded numbers for eng\etc\, which it then did, for all five. The extraction was right and the assumption that FILES' path was the one the corpus had measured was wrong.

What this does not settle

• The 2 unaccounted TOC entries.
• The Japanese bank layout. 4 301 banks have a RIFF at an unaligned offset and 799 have none at all; neither shape has been decoded, and no Japanese bank has been decoded to audio here.
• Why 55 English banks have their first RIFF at or before 1392, inside what the headerless reading treats as the header.
• Nothing here was run. This is a static census of the archive.

✅ A full bank manifest — and the durations validate the whole chain

2026-08-26. With the wave boundary exact and Channels read rather than assumed, every field needed to describe a bank can be read:

path | cue | sound id | channels | rate | data bytes | packets | samples | seconds

Committed as ../data/voice-bank-manifest.txt — 4 114 banks, every one carrying a full RIFF/fmt /data/seek structure. (1 021 of the 5 135 FILES paths have no RIFF and are excluded; those are the headerless banks.) Duration comes from the last cumulative sample in the seek table divided by the sample rate — arithmetic, no decoding.

Total: 408.3 minutes — about 6¾ hours of audio. ⚠️ An earlier version of this page said 390.9 minutes, computed from the seek table's sample total; that understates the true length by a median 9.7 % per bank. See slb-data-offset.md.

The reason this is worth more than a listing is that nothing in it was fitted to an expectation, yet every category lands where its content says it should:

directory	banks	total	mean	longest
root (BGM_*, JNGL_*)	34	82.8 min	146.0 s	277.5 s
Movie	62	81.4 min	78.8 s	672.7 s
Briefing	72	12.9 min	10.8 s	26.8 s
etc	1 776	112.9 min	3.8 s	136.8 s
Voice	2 170	100.9 min	2.79 s	7.3 s

Music tracks average two and a half minutes; a cutscene track runs up to eleven minutes; briefing lines are ten seconds; and in-mission radio chatter averages 2.8 seconds and never exceeds 7.3. If the boundary rule, the channel field or the seek table were being misread, these numbers would not sort themselves into those five shapes.

Two incidental facts fall out: 4 banks run at 44 100 Hz where everything else is 48 000, and the BGM_* tracks are the stereo ones.