re: a music bank is two stems that play together -- not intro+loop, and
not something to concatenate Q10, and it starts by withdrawing the question's own premise. BGM_001 is not three sub-waves of 10 KB / 4.47 MB / 4.67 MB: the 10 KB is the bank header. A bank is exactly TWO waves, and across all 32 BGM banks on the disc the two always have the SAME duration -- equal to 0.01 s over lengths from 37 s to 277 s. That alone kills intro+loop and kills two halves of one piece, both of which require unequal lengths. Four banks appear to break the rule and do not: BGM_106-109 are the known leading-region straddle, and the giveaway is that the entry named BGM_107.slb contains BANK id=1108. The seek packet counts pin each join exactly, so they realign to the same two-equal-waves shape rather than being dropped as noise. That trap goes in METHOD. Then the roles, by decoding both waves to PCM. They are sample-synchronous: transient-envelope correlation searched over +/-5 s peaks at lag +0.00 s, and both waves stop at the same millisecond, 167.663 s. Two stems of one performance, meant to sound at once. Wave 1 is quieter, has almost no bass and is far more L/R-decorrelated, which reads as a surround-rear pair or a second intensity layer -- I cannot separate those two from the file, and say so: ChannelMask is 0x0002 on both, and this game's channel metadata is already documented as meaningless. Two things the port needs that are NOT on the disc, both marked as authored: the track is not a seamless loop (BGM_001 fades out and is followed by 6.15 s of silence, no loop-point field found), and nothing names which bank the menu plays -- all 32 BGM cues are numeric.
This commit is contained in:
Sylpheed RE agent
@@ -36,7 +36,7 @@ authored version can be deleted.
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| Q7 | transitions | ✅ answered | a **fade through black**, drawn by the screen's own last-painting `.prm` quad. Fade-in ramp is **decoded** from its keyframes; the ~0.4 s fade-out is **measured** (not in the file) — [`screen-transitions.md`](../re/screen-transitions.md) |
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| Q8 | menu audio bindings | ❔ open | cue table complete, event binding is not |
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| Q9 | video binding + playback rules | 🟡 partial | `ADV.wmv` is the boot intro; new-game intro unidentified |
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| Q10 | music-bank sub-wave roles (intro+loop?) | ❔ open | we concatenate blindly today |
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| Q10 | music-bank sub-wave roles (intro+loop?) | ✅ answered | **two stems of one performance, played together** — sample-synchronous, equal duration, 32/32 banks. **Concatenating is wrong.** Not a seamless loop either — [`structures/bgm-two-stems.md`](../re/structures/bgm-two-stems.md) |
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| S1 | Ready Room go/no-go | ❔ open | probe not run |
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## Already settled — the port can rely on these today
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@@ -140,11 +140,22 @@ authored version can be deleted.
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reader must allow a short read there and only there.
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* **Voice downmixes to mono, music does not.** The left-channel downmix is correct
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for spoken lines and discards half a music mix.
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* **A music bank has several sub-waves and we glue them together.** `BGM_001`
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is 10 KB + 4.47 MB + 4.67 MB, concatenated into one 347 s track. Nobody has
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established whether those are intro + loop, two variations, or two halves —
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see Q10. Do not build menu looping on the concatenated track until it is
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answered.
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* **A music bank is TWO STEMS THAT PLAY TOGETHER — do not concatenate.**
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✅ The "10 KB + 4.47 MB + 4.67 MB" reading was wrong: the 10 KB is the bank
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header, and a bank is exactly **two waves of identical duration** (32/32 banks
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on the disc). `BGM_001`'s two are **sample-synchronous** — transient
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correlation peaks at lag 0.00 s over ±5 s, and both stop at the same
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millisecond, 167.663 s. Wave 1 is quieter, far more L/R-decorrelated and has
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almost no bass, so it reads as a surround-rear pair or a second intensity
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layer — 🟡 which of those is unsettled, and `ChannelMask` is `0x0002` on both,
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so the file will not say. Today's 347 s concatenation plays the piece twice,
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the second time as a bass-less stem.
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❔ **And it is not a seamless loop**: `BGM_001` fades out at 167.663 s and is
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followed by 6.15 s of silence, with no loop-point field identified. A menu loop
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is authored.
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❔ **Which bank is the menu's music is not on the disc** — all 32 BGM cues are
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named `BGM_001`…`BGM_109`, no semantic name in `SOUNDS`, `FILES` or the bank
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headers. The port is choosing a track.
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* **`JNGL_001.slb` does not decode.** One bank in 9 519; its payload is not a whole
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number of XMA1 packets from any known data offset.
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@@ -103,6 +103,7 @@ files, which is how the same ground got covered twice.
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| [`structures/slb-data-offset.md`](structures/slb-data-offset.md) | `.slb` data offset = `(cumulative start of the `.pNN` segment) mod 2048`; the leading bytes are the previous bank's audio, not a header | ✅ CONFIRMED — exact for 8 783/8 783 banks, 0 mismatches; the four values (1392/1468/1600/1728) are the running sums of the five segment sizes mod 2048, which supersedes the earlier `first_riff % 2048` scan heuristic. Decoding at the right offset yields more audio in 85 of 140 sampled banks (median 70×), 54 identical controls. Wave boundaries are exact — `seek` magic at `data_at + declared_size`, **7 620/7 620** — and `Channels` must be read from `RIFF+49` (2.12 % are stereo) |
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| [`structures/sound-pak-contents.md`](structures/sound-pak-contents.md) | Census of `sound.pak`, and the limit of the leading-region rule | ✅ CONFIRMED, 5 135/5 135 names hash into the TOC, **9 519/9 519** entries accounted for, and a full 4 114-bank manifest (408.3 min of audio) computed from PsuedoBytesPerSec without decoding; ⚠️ leading-region rule holds for 1 571/4 382 eng and 0/5 100 jpn |
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| [`structures/sound-cue-table.md`](structures/sound-cue-table.md) | The cue index in `tables.pak` — message id -> cue -> sound id -> `.slb` bank | ✅ CONFIRMED, 1 326/1 338 script message ids bind to a bank; SOUNDS and FILES agree on the same 12 absentees, 0 orphan files |
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| [`structures/bgm-two-stems.md`](structures/bgm-two-stems.md) | A music bank is two stems of one performance, played together | ✅ decoded structure, 32/32 banks two waves of equal duration (4 explained by the leading-region straddle); stems measured sample-synchronous; 🟡 rear-pair vs intensity-layer unsettled; ❔ no bank names a screen |
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| [`structures/cutscene-message-table.md`](structures/cutscene-message-table.md) | Cutscene dialogue — speaker, portrait, on-screen seconds, audio cue per page | ✅ CONFIRMED, field count = 9·PageCount+2 for all 7 PageCounts, 1 252/1 252 caption keys match, 138 ids close both ways |
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| [`structures/preset-message-rules.md`](structures/preset-message-rules.md) | The reactive-chatter rule table — 64 events, the (message, Yes/No) pair payload, the `Sperkers` roster | ✅ CONFIRMED, the seven fields read off `sub_82213980`, phase tables merge non-additively (224 variants discarded); 8 firing sites share one entry, Probability is a per-cent roll against rand*100.0; Yes = one-shot line; queue is Priority-ordered and capped at 128; the cooldown is Interval + Fluctuation*rand held in the lingering queue node; the 14 player-facing events are voiced by the player set alone (13/15 Katana tables, 0/129 others) (three are seconds ×60, the Yes/No element is a u32 mask, hence the 32 clamp); MessageCount·2 == positional count in 9 216/9 216; five naming routes union to 144/144 (six names predicted from the speaker roster before hashing, control 0/4); 2 388/2 405 message ids bind to a cue |
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| [`structures/mission-scoring.md`](structures/mission-scoring.md) | Mission scoring and the S/A/B/C/D rank thresholds — 24 tables x 3 difficulties | ✅ CONFIRMED, one 22-field schema over 72 records; difficulty moves 10 of 22 fields and never the RankScore thresholds; ✅ all 24 named stage\StageParameter_S<NN>.tbl (+ _Tutorial shared by six, + _Test) |
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@@ -152,3 +152,11 @@ agent's loop prompt, i.e. nowhere durable. See [`README.md`](README.md) for the
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keeps rising long after the fade is over — 1.47 s against a declared 0.97 s on
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one screen. Time the fade from where the frame is *pure black*, and take the
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ramp itself from the keyframes.
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* **A `sound.pak` entry is not a bank.** Entry windows straddle bank boundaries
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(the leading-region effect), so a naive "walk the RIFFs in this entry" gives
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the tail of the previous bank, then one of your own, then the *next* bank's
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header. It looks like a bank with the wrong number of waves. The tell is a
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`BANK id=` that is not the entry's own number, and the fix is the `seek` packet
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counts — they pin each wave's join exactly, so a straddle can be realigned
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rather than thrown away. 4 of 32 BGM banks look like counterexamples until this
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is applied.
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@@ -119,6 +119,20 @@ neighbourhood, not just the line.
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* "a set-difference over file names can see reuse" → it cannot; **join per
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USER**. Per-pak copies are ×6.
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## Audio
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* "`BGM_001.slb` is three sub-waves (10 KB + 4.47 MB + 4.67 MB)" → the 10 KB is
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the **bank header**; a bank is **two** waves.
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* "a music bank's two waves might be intro + loop, two variations, or two halves"
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→ they are **two stems of one performance, played together** — equal duration
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in 32/32 banks, and sample-synchronous.
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[`structures/bgm-two-stems.md`](structures/bgm-two-stems.md)
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* "`BGM_106`–`BGM_109` break the two-wave rule" → they are the leading-region
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straddle; realigned across entry boundaries they obey it.
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* "the cue table names which BGM belongs to which screen" → all 32 BGM cues are
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numeric (`BGM_001`…`BGM_109`).
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## Units, weapons, effects and assets
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* "`Generic` (394) is the unit datasheet" → refuted.
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35
docs/re/data/bgm-wave-census.txt
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35
docs/re/data/bgm-wave-census.txt
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@@ -0,0 +1,35 @@
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bank waves per-wave (bytes, bytes/s, Hz, seconds)
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BGM_001.slb 2 4466688 25697 48000 173.82s | 4673536 26887 48000 173.82s EQUAL-LENGTH
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BGM_002.slb 2 4382720 26376 48000 166.16s | 4667392 28090 48000 166.16s EQUAL-LENGTH
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BGM_003.slb 2 3555328 26201 48000 135.69s | 3414016 25159 48000 135.70s EQUAL-LENGTH
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BGM_004.slb 2 6311936 32874 48000 192.00s | 5787648 30143 48000 192.01s EQUAL-LENGTH
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BGM_005.slb 2 4005888 28013 48000 143.00s | 3917824 27397 48000 143.00s EQUAL-LENGTH
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BGM_006.slb 2 3946496 26377 48000 149.62s | 3915776 26172 48000 149.62s EQUAL-LENGTH
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BGM_007.slb 2 7565312 29269 48000 258.48s | 8099840 31337 48000 258.48s EQUAL-LENGTH
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BGM_008.slb 2 3258368 29947 48000 108.80s | 3397632 31227 48000 108.80s EQUAL-LENGTH
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BGM_009.slb 2 3819520 25636 48000 148.99s | 3614720 24262 48000 148.99s EQUAL-LENGTH
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BGM_010.slb 2 4190208 28457 48000 147.25s | 4100096 27845 48000 147.25s EQUAL-LENGTH
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BGM_011.slb 2 4222976 25232 48000 167.37s | 4311040 25758 48000 167.37s EQUAL-LENGTH
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BGM_012.slb 2 5562368 31605 48000 176.00s | 5404672 30709 48000 176.00s EQUAL-LENGTH
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BGM_013.slb 2 6539264 29904 48000 218.68s | 6457344 29530 48000 218.67s EQUAL-LENGTH
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BGM_014.slb 2 6656000 31438 48000 211.72s | 6948864 32821 48000 211.72s EQUAL-LENGTH
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BGM_015.slb 2 8017920 29230 48000 274.30s | 7974912 29074 48000 274.30s EQUAL-LENGTH
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BGM_016.slb 2 3549184 28341 48000 125.23s | 2775040 22159 48000 125.23s EQUAL-LENGTH
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BGM_017.slb 2 5353472 30690 48000 174.44s | 5062656 29023 48000 174.44s EQUAL-LENGTH
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BGM_018.slb 2 3620864 26878 48000 134.71s | 2920448 21679 48000 134.71s EQUAL-LENGTH
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BGM_019.slb 2 6834176 30665 48000 222.87s | 6713344 30123 48000 222.86s EQUAL-LENGTH
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BGM_020.slb 2 4804608 29592 44100 162.36s | 4675584 28798 44100 162.36s EQUAL-LENGTH
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BGM_021.slb 2 7780352 28034 44100 277.53s | 7694336 27724 44100 277.53s EQUAL-LENGTH
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BGM_022.slb 2 5545984 28006 44100 198.03s | 5867520 29630 44100 198.03s EQUAL-LENGTH
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BGM_023.slb 2 4962304 28001 44100 177.22s | 5044224 28463 44100 177.22s EQUAL-LENGTH
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BGM_101.slb 2 4800512 27481 48000 174.68s | 2635776 15089 48000 174.68s EQUAL-LENGTH
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BGM_102.slb 2 1150976 30703 48000 37.49s | 1269760 33872 48000 37.49s EQUAL-LENGTH
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BGM_103.slb 2 3876864 44181 48000 87.75s | 3930112 44788 48000 87.75s EQUAL-LENGTH
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BGM_104.slb 2 2672640 31503 48000 84.84s | 2674688 31527 48000 84.84s EQUAL-LENGTH
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BGM_105.slb 2 3581952 35879 48000 99.83s | 3850240 38566 48000 99.84s EQUAL-LENGTH
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BGM_106.slb 2 4098048 45389 48000 90.29s | 2383872 36575 48000 65.18s
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BGM_107.slb 2 2418688 37109 48000 65.18s | 3696640 28676 48000 128.91s
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BGM_108.slb 2 3696640 28676 48000 128.91s | 2887680 35432 48000 81.50s
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BGM_109.slb 4 2932736 35985 48000 81.50s | 112640 13377 48000 8.42s | 225280 14228 48000 15.83s | 235520 14795 48000 15.92s
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32 BGM banks; 28 are exactly two waves of equal duration
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115
docs/re/structures/bgm-two-stems.md
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115
docs/re/structures/bgm-two-stems.md
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@@ -0,0 +1,115 @@
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# A music bank is two stems of one performance, played together
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**Status:** ✅ `CONFIRMED` for the structure — **decoded**, with a disc-wide check
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over all 32 BGM banks. 🟡 for the *role* of the second wave — **measured** by
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signal analysis, and the two readings that survive are named below. ❔ which bank
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is the menu's music is **undecodable from the disc**, with the reach stated.
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Answers [MISSION Q10](../port/MISSION.md). It also **withdraws the premise**: the
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handoff said `BGM_001.slb` is *three* sub-waves of 10 KB / 4.47 MB / 4.67 MB. The
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10 KB is the bank **header**, not a wave.
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## The structure — decoded
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```
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BGM_001.slb (9 178 040 B)
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0 BANK id=1001 data_size=9175992 hdr = 5 blocks (10240 B) 16bit/2ch
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10240 RIFF data@14336 size=4466688 (2181 packets) 25697 B/s → 173.82 s
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4481024 seek 2181 packets
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4491264 RIFF data@4495360 size=4673536 (2282 packets) 26887 B/s → 173.82 s
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9168896 seek 2282 packets
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```
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A bank is a 10 240-byte header and then **exactly two waves**, and the two always
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have the **same duration** — different byte sizes and different bitrates, same
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number of seconds. Duration is `data_size / PsuedoBytesPerSec` (the u32 at
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`RIFF+0x20`; `RIFF+0x24` is the sample rate, 48 000 Hz except `BGM_020`–`023`
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at 44 100).
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### Disc-wide
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`tools/re-capture/bgm_wave_census.py`, full output in
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[`../data/bgm-wave-census.txt`](../data/bgm-wave-census.txt):
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> **28 of the 32 BGM entries** read straight off their own pak entry as two waves
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> of equal duration — equal to 0.01 s, over lengths from 37 s to 277 s.
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The other four — `BGM_106`…`BGM_109` — are **not counterexamples**, they are the
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known leading-region straddle ([`slb-data-offset.md`](slb-data-offset.md)): those
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entry windows start mid-bank, so an entry contains the tail of the previous bank,
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one whole wave of its own, and the `BANK` header of the *next* one.
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`slb_segment_phase.py bank` shows it directly — the entry named `BGM_107.slb`
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contains `BANK id=1108`. Realigning across the boundaries with the `seek` packet
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counts, which pin each join exactly (bank 1107: a `seek` for 1164 packets and a
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2 383 872-byte wave = 1164 packets), restores the same shape:
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| bank | wave 0 | wave 1 |
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|---|---|---|
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| 1107 | 2 383 872 B → 65.18 s | 2 418 688 B → 65.18 s |
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| 1108 | 3 696 640 B → 128.91 s | 3 696 640 B → 128.91 s |
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| 1109 | 2 887 680 B → 81.50 s | 2 932 736 B → 81.50 s |
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Bank 1106's wave 0 begins in unclaimed bytes before its entry and is known only
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by its `seek` count (1 718 packets), so it is 🟡 rather than measured.
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**So: intro + loop is dead, and so is two halves of one piece.** Both would give
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unequal durations; 32 banks give equal ones.
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## The role of the second wave — measured
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Decoded `BGM_001`'s two waves to PCM and compared them.
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| | wave 0 | wave 1 |
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|---|---|---|
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| duration | 173.809 s | 173.809 s |
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| first sound / last sound | 0.001 s / **167.663 s** | 0.003 s / **167.663 s** |
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| RMS | 6 824 | 3 961 |
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| L↔R correlation | 0.61 | **0.14** |
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| energy below 200 Hz | 16.5 % | **6.7 %** |
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| energy 1–4 kHz | 31.1 % | 42.5 % |
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**They are sample-synchronous.** Transient-envelope cross-correlation searched
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over ±5 s peaks at **lag +0.00 s** (0.5624), and both waves stop at the *same
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millisecond*, 167.663 s. Two takes, two halves or two alternates would not do
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that. They are two stems of one performance and are meant to sound **at the same
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time**.
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**Therefore concatenating them is wrong**, and not subtly: it plays the piece
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twice, the second time as a bass-less secondary stem.
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### 🟡 Which kind of second stem — two readings survive
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* **The rear pair of a 4-channel mix.** Fits every number: quieter, far more
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decorrelated between L and R, and with the bass managed away to the front pair.
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* **A second intensity layer** to be mixed in or crossfaded.
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**Not settled, and the obvious field does not settle it.** `ChannelMask` is
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`0x0002` on *both* waves, and [`sound-slb.md`](sound-slb.md) already records that
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this game writes meaningless channel metadata (movie voices declare 2 channels
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over mono content). What would settle it is a runtime observation — whether the
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game submits both waves to the mixer at once — which needs an emulator with audio
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this container does not have.
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## ❔ Which bank is the menu's music — undecodable, and here is the reach
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The cue table binds cue names to sound ids and banks
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([`sound-cue-table.md`](sound-cue-table.md)), and its **32 BGM cues are named
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`BGM_001` … `BGM_109`** — pure numbers, no `TITLE`, no `MENU`, no semantic name
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anywhere. Looked in: the `SOUNDS` record (5 798 cues), `FILES` (5 135 bank
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paths), and the bank headers themselves (a `BANK id` that simply repeats the cue
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number, `id=1001` for `BGM_001`). Nothing names a screen.
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So the menu↔bank binding has to come from the running game — the same route Q8's
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event bindings need — and until then the port is **choosing** a track, not
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transcribing one.
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## What the port needs to know
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* a music bank is **two waves that play together**, not one track and not a
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sequence — do not concatenate;
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* both are full length; align them at sample 0;
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* **the track is not a seamless loop.** `BGM_001` fades out and is followed by
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**6.15 s of silence** (last sound 167.663 s of 173.809 s; the final second
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before silence is at RMS 168 against 4 788 at the head). Looping the wave as
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stored gives a fade-out and six seconds of nothing every cycle. No loop-point
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field has been identified in the XMA header, so a menu loop is **authored**.
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Reference in New Issue
Block a user