re: the capture recipe that passes, and a five-stream observation it turned up

Take 2 of the ADV audio capture verified with the port s independent
tools/port/check-capture -- six distinct channel MD5s, PASS -- run before
sharing and deliberately using their tool rather than the hand that made the
file.

Records the recipe: sink channel_map set equal to Canary s own stream map and
the same map passed to parec, so PulseAudio does no remapping; both of
run-canary s mutes off; recorder started before the emulator so WAV t=0 precedes
process launch; and a screenshot every ~11 s keyed to the recording s own clock.

That last pair is what makes it self-checking, and both were the port s asks.
Classified against the committed references, this run reads movie/other for
t=10..251 and then title_noplate at t=262 (r=+0.998) and title_plate at 277/289
-- so the 253 s of audio sits wholly inside the movie with the title arriving
just after. A miss is now diagnosable instead of ambiguous, which is the whole
difference from take 1.

Still the full mix: movie WMA bed plus voice, nothing at this boundary separates
them.

Also records something unexplained that the run turned up: the probe logged FIVE
distinct XMA byte_size values, not three -- ADV s 1294336 / 1118208 / 1171456
plus 1150976 and 1269760. The extra pair belongs to some other cue, is not
BGM_103 s two waves, and a pair is the shape bgm-two-stems documents for music
banks. Untested.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd

docs/re/audio-capture-channel-map-trap.md

@@ -109,3 +109,43 @@ the capture chain and check that it comes back.** It was not run, an artefact wa
 published, and the person who found the defect was the one who could not see the
 instrument. ⚠️ **A capture is an instrument, not just an output** — the same
 scrutiny a parser or an estimator gets.
+
+---
+
+## ✅ The capture that passes — recipe, and how it proves itself
+
+Take 2, 2026-08-29. Verified with the port's independent
+`tools/port/check-capture` (six distinct channel MD5s → PASS) **before** being
+shared, deliberately using their tool rather than the hand that made the file.
+
+```bash
+MAP=front-left,front-right,front-center,lfe,rear-left,rear-right   # Canary's own
+pactl load-module module-null-sink sink_name=cap channels=6 channel_map=$MAP
+parec -d cap.monitor --channels=6 --rate=48000 --format=s16le \
+      --channel-map=$MAP --file-format=wav out.wav &      # recorder FIRST
+PULSE_SINK=cap SDL_AUDIODRIVER=pulseaudio \
+  run-canary --mute=false …                                # both mutes off
+```
+
+Two properties make it self-checking, and both were the port's asks:
+
+* **The recorder starts before the emulator**, so WAV `t=0` precedes process
+  launch and the movie cannot fall outside the window by accident.
+* **A screenshot every ~11 s, keyed to the recording's own clock.** Classified
+  against the committed references afterwards, this run reads `movie/other` for
+  **t = 10 … 251** and then `title_noplate` at **t = 262** (r = +0.998),
+  `title_plate` at 277/289. So the 253 s of audio sits wholly inside the movie,
+  with the title arriving just after it ends. **A miss would now be diagnosable
+  instead of ambiguous** — which is the whole difference from take 1.
+
+⚠️ It is still the **full mix** — the movie's own WMA bed plus the voice streams.
+Nothing at this boundary separates them.
+
+## ❔ New, unexplained: this run decoded FIVE XMA streams, not three
+
+`--xma_param_probe` on the take-2 boot logs five distinct `byte_size` values:
+`ADV`'s three (**1 294 336 / 1 118 208 / 1 171 456**) plus **1 150 976** and
+**1 269 760**. The extra pair belongs to some other cue and is unidentified —
+they are not `BGM_103`'s two waves (3 876 864 / 3 930 112). A *pair* is the shape
+[`bgm-two-stems`](structures/bgm-two-stems.md) documents for music banks, so a
+second bank is the first guess and it is untested.