dcfb53bc9b
Coherence on BGM_103, the menu's bank, with controls run first: a real linear filter of wave 0 reads 0.93-0.94 in every band, a different bank reads 0.001, and wave 0 misaligned by 1 s reads 0.004-0.057. The measurement reads 0.027 at 1-4 kHz, so the 'wave 1 is wave 0 filtered' model is refuted. The frequency structure is inverted relative to any mic-pair or reverb model: coherence rises with frequency (0.169 -> 0.827) while energy falls (71 % -> 0.2 %), and a rear pair decorrelates fastest at HF. In the midrange the two waves are 13x further apart than the two channels of one wave. But the L-R control is what limits the tool and it is recorded as such: within one wave, genuinely one performance in two channels, coherence is only 0.221-0.497. So 'same performance' does not imply high coherence here, my positive control was the wrong model of the rear-pair reading, and the 🟡 is NOT settled. The tool tests for linear filtering and neither surviving reading requires it. Also corrects MISSION's Q10 row, which still carried the refuted three-sub-wave premise and had directed work at a dead question for days. Its gate is in fact met. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v
72 lines
4.2 KiB
Plaintext
72 lines
4.2 KiB
Plaintext
# Is a music bank's wave 1 the SAME instruments filtered, or DIFFERENT parts?
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# BGM_103 (the menu's music) -- 2026-08-30
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#
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# structures/bgm-two-stems.md leaves two readings alive for wave 1: the rear
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# pair of a 4-channel mix, or a second intensity layer -- and correctly notes
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# that runtime simultaneity cannot separate them, because both predict it.
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# This is a static attempt at a discriminator.
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#
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# METHOD: magnitude-squared coherence, Welch, NFFT 8192 @ 48 kHz, 60 s window
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# (702 segments, so the bias floor is ~1/702 = 0.0014). Coherence is ~1 wherever
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# one signal is a LINEAR FILTER of the other and ~0 for independent signals.
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# tools/re-capture/bgm_stem_coherence.py
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#
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# WAVES: slb_extract_wave.py BGM_103.slb 14336 1893 2 48000 (wave 0)
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# slb_extract_wave.py BGM_103.slb 3903488 1919 2 48000 (wave 1)
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# then ffmpeg -i x.riff x.wav. Both decode to 87.744 s, 4 211 729 frames.
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# CONTROL BANK: BGM_104.slb 14336 1305 (a different piece, same codec).
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#
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CONTROLS
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POS w0 vs linear-filter(w0) 0-0.2k 0.929 0.2-1k 0.938 1-4k 0.936 4-12k 0.938 12-16k 0.938 16-24k 0.937
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NEG w0 vs a different bank 0-0.2k 0.001 0.2-1k 0.001 1-4k 0.001 4-12k 0.001 12-16k 0.001 16-24k 0.002
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NEG w0 vs w0 shifted 1 s 0-0.2k 0.057 0.2-1k 0.048 1-4k 0.007 4-12k 0.019 12-16k 0.015 16-24k 0.004
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REF w0 L vs R (one perf.) 0-0.2k 0.321 0.2-1k 0.221 1-4k 0.363 4-12k 0.445 12-16k 0.497 16-24k 0.450
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REF w1 L vs R (one perf.) 0-0.2k 0.078 0.2-1k 0.051 1-4k 0.089 4-12k 0.411 12-16k 0.453 16-24k 0.455
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MEASUREMENT
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w0 vs w1 0-0.2k 0.169 0.2-1k 0.184 1-4k 0.027 4-12k 0.635 12-16k 0.768 16-24k 0.827
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ENERGY SHARE
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w0 0-0.2k 71.4% 0.2-1k 24.8% 1-4k 2.4% 4-12k 1.0% 12-16k 0.1% 16-24k 0.2%
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w1 0-0.2k 53.8% 0.2-1k 40.9% 1-4k 2.3% 4-12k 2.1% 12-16k 0.3% 16-24k 0.6%
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# ------------------------------------------------------------------------------
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# READING IT
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#
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# ✅ THE INSTRUMENT IS CALIBRATED. A real linear filter of w0 reads 0.93-0.94 in
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# every band; a different bank reads 0.001-0.002; w0 against itself misaligned by
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# 1 s reads 0.004-0.057. So the estimator detects filtering and is not fooled by
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# two pieces of music in the same codec.
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#
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# ❌ REFUTED: "wave 1 is wave 0 put through a filter." The positive control says
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# a filter reads 0.936 at 1-4 kHz. The measurement reads 0.027 there. No linear
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# filter produces that in a band where both waves carry energy.
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#
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# 📌 THE FREQUENCY STRUCTURE IS INVERTED relative to any mic-pair or reverb
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# model. Coherence RISES with frequency -- 0.169, 0.184, 0.027, 0.635, 0.768,
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# 0.827 -- while energy FALLS -- 71.4 %, 24.8 %, 2.4 %, 1.0 %, 0.1 %, 0.2 %.
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# A rear pair or a reverb return decorrelates FASTEST at high frequency, which
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# is the opposite. What is coherent lives in bands holding ~1.3 % of the energy;
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# the bands holding 96 % of it read 0.169 and 0.184.
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#
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# 📌 AND IN THE MUSICAL MIDRANGE THE TWO WAVES ARE FURTHER APART THAN THE TWO
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# CHANNELS OF ONE WAVE: 1-4 kHz gives 0.027 between waves against 0.363 for w0's
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# own L vs R -- a factor of 13. Two channels of one performance agree far more
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# than the two waves do.
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#
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# 🔴 BUT THE L-R CONTROL IS ALSO WHAT LIMITS THIS TOOL, AND IT KILLS THE CLEAN
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# ANSWER. L vs R within a single wave is genuinely "one performance, two
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# channels", and it reads only 0.221-0.497 -- nowhere near the 0.94 a filter
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# gives. So in THIS material "same performance" does not imply high coherence,
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# which means my positive control was the wrong model of the rear-pair reading:
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# a real 4-channel mix's rear pair is not a linear filter of its front pair.
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#
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# => The filter model is dead. The two named readings are NOT separated. This
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# tool cannot separate them, and the reason is stated rather than discovered
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# later: it tests for linear filtering, and neither reading requires it.
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#
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# ⚠️ REACH: one bank (BGM_103), one 60 s window, mono-summed for the coherence
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# rows. Not run over the other 31 banks. The 16-24 kHz reading of 0.827 sits in
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# 0.2-0.6 % of the energy and is unexplained -- it is NOT generic codec
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# behaviour, since the different-bank control reads 0.002 in the same band.
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