1eb36c2b9d
Probed all 97 movies. 28 are wmapro 48 kHz 6-channel 5.1 -- ADV.wmv and every S*.wmv story cutscene; the other 69 are wmav2 48 kHz stereo, every RT*.wmv and hokyu_*.wmv. The split is cinematics vs in-mission radio chatter. Both movies the menu milestone needs, ADV.wmv (the boot/attract intro) and S00A.wmv (the new-game intro), are in the SURROUND group. Why it matters: one ffmpeg command over dat/movie/ produces two different kinds of result and records neither. The 69 stereo files pass through unchanged; the 28 surround files get downmixed 5.1 -> stereo by ffmpeg's DEFAULT matrix, folding centre-channel dialogue into L/R at a weighting nobody chose and which is not stable across ffmpeg versions. That is a content decision inherited by accident, so it should be stated explicitly and recorded beside the command. Credit where due: found by the human while checking a transcode, verified independently here and widened from one file to the whole disc. Two METHOD entries from the same episode, both about measurement rather than format: don't probe a file another process is still writing (a half-written transcode reported 33 s against a 137 s source, no error, nearly a filed bug), and a difference-signal RMS is meaningless before cross-correlation alignment (-34.2 dB against a -25.3 dB source looks like failure and is inconclusive).
2.1 KiB
✅ The disc ships movies in two audio profiles — and one of them is 5.1
Status: ✅ DECODED, disc-wide (97 of 97 movies probed). Found while checking
a transcode, not while looking for it.
The split
$ ffprobe -select_streams a -show_entries stream=codec_name,sample_rate,channels,channel_layout
| profile | count | codec | rate | channels | which |
|---|---|---|---|---|---|
| surround | 28 | wmapro |
48 kHz | 6 (5.1) | ADV.wmv + every S*.wmv story cutscene |
| stereo | 69 | wmav2 |
48 kHz | 2 | every RT*.wmv and hokyu_*.wmv |
Full list in data/movie-audio-layouts.csv.
The split is not arbitrary: the cinematics are 5.1 and the in-mission radio
chatter is stereo. ADV.wmv (137.714 s) and S00A.wmv — the boot/attract intro
and the new-game intro, i.e. both movies the menu milestone needs — are in the
surround group.
⚠️ Why this matters to anything that transcodes
A single ffmpeg command over dat/movie/ produces two different kinds of
result and records neither:
- the 69 stereo files pass through channel-wise unchanged;
- the 28 surround files are downmixed 5.1 → stereo by ffmpeg's default matrix, folding centre-channel dialogue into L/R at a weighting nobody chose.
That default is a content decision — it sets how loud the dialogue is against the music — and it is not stable across ffmpeg versions. A pipeline that wants a reproducible result has to state the downmix explicitly rather than inherit it, and record it beside the command.
🟡 Whether the game itself plays these in surround, and with what downmix when the console is set to stereo, is not established here. This page is about what is on the disc.
How it was found, and the trap next to it
Checking a transcode against its source, ffprobe reported the output as 33 s
against the source's 137 s — which reads as catastrophic truncation and is not:
the file was being written at that moment. Measuring a live write produces a
confident wrong answer with no error. See ../METHOD.md.