Threshold and min-interval (the librosa delta/wait knobs) were only
ever tunable via the CLI's -t/-m flags. Added a Clap Detection
Settings dialog (Tools menu) with both as spin boxes, an explicit
Reset to Defaults button, and Cancel that leaves MainWindow's current
settings untouched.
Exposed DEFAULT_THRESHOLD=0.7/DEFAULT_MIN_INTERVAL=0.3 as named
constants in clap_detection.py so the CLI script, DetectWorker's
defaults, and the dialog's reset button all reference the same source
of truth instead of three copies of the same magic numbers that could
drift apart.
Ports scripts/detect_claps.py (a librosa-based onset detector from an
earlier session) into clap_detection.py, shared by both the CLI script
and a new GUI feature: 'Detect All Claps' (whole-file scan) and
'Detect Next Clap' (from cursor, first result only), with results
shown as clickable markers on a new MarkerStrip widget above the seek
slider -- clicking one seeks the player to that exact timestamp.
Caught a real correctness bug while testing against the out-of-sync
fixture (not just the plain in-sync one): ffmpeg's default -vn audio
extraction silently drops the audio stream's own start_time and
renormalizes to t=0 -- which is exactly the offset this whole tool
exists to fix, so losing it meant detected timestamps pointed at the
wrong track's timing entirely. Fixed by probing the true start_time
via ffprobe and re-inserting it as explicit silence (adelay) before
analysis. Also dropped an earlier attempt at an ffmpeg -ss seek
optimization for the from-cursor case, since combining it with the
start_time fix meant two independent timestamp-origin corrections
stacked on each other -- correct in theory, too easy to get subtly
wrong in a tool where a silent wrong-timestamp bug is the worst
possible failure mode. Full-file decode + filter in Python is slower
but unambiguous.
Verified with a smoke test that drives the real MainWindow buttons,
confirms the detected marker lands near the fixture's known beep
(t=5.350s, allowing for onset-detection lag), and simulates an actual
QMouseEvent click on the marker to confirm click-to-seek works
end-to-end.