The four durations withdrawn yesterday were produced by a classifier costing
1503 ms/frame draining an 8 fps x11grab at 0.64 fps -- a backlog, which
preserves ordering and destroys durations. This is the instrument for retaking
them.
What makes it cheap: every committed capture aligns at exactly dy=0 dx=0
(five-screens-acceptance), so the +/-8 px offset search screen_match does at
full resolution is 25 ZNCCs buying nothing on this path. Decimate 4x, do one
ZNCC per reference. Measured 8.7 ms per frame including the glyph count -- 173x.
Controls, run before the measurement and not after it:
* 9/9 content controls, including the two committed movie frames that are the
class this oracle exists to reject;
* 4/4 on the plate detector itself, which is a threshold on the green-glyph
counter and so needs its own control (no-plate title 159, plate title 753,
movie frames 0).
And three things learned from run 1, folded back in:
* do NOT restart the stream once the measurement is under way. Run 1's restart
landed 0.25 s after the (A) press and its stale frames straddled exactly the
interval being timed;
* press INLINE, not through pad.py's subprocess -- an interpreter start plus
the 0.25 s hold sat between the press and the timestamp;
* count the longest run of byte-identical surface means and report it. That is
the freeze signature, and it is how run 2 showed the 26.626 hold is the
guest rather than the capture path.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014voBspJ6kFncNErZJuZcLw
