The port kept 60 on a stated constraint: the transition quad is declared
black for 12 units, measured at 0.14-0.30 s, giving 40-86 units/s, so 60 is
in and 120 is out. Attempted to refute it, and it does not hold.
Two reasons, either sufficient.
The low end is the instrument's floor. title-plate-delay-measured.md says
of that number, in its own words, "at a sampling resolution (0.125 s) that
cannot do better". 0.14 s IS one sample. At 120 units/s, 12 units is
0.100 s, which a 0.125 s sampler reports as roughly 0.14 s -- exactly the
value read as excluding it. The 86 units/s upper limit is an artefact of
dividing by a floored duration.
And a wall-clock duration off Canary is not independent of the unknown.
Apparent units/s = true units/s x speed factor, and the speed factor is
precisely what makes the three routes disagree. The bracket says "if Canary
ran at real time, 40-86" and whether it did is the question.
What survives is the declared side, and it is a disc fact worth keeping:
the transition opens over 12 units, independently confirmed as 6 frames by
screen-transitions.md's 255/6-per-frame ramp. That leg has no wall clock in
it and is real evidence -- for units per FRAME, which was never in dispute.
This does not argue for 120. Nothing supports 120 either. It removes a
reason for excluding it, and my position is unchanged: the value is
authored until the content-hash experiment runs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
Published this morning, withdrawn the same day. The measurement was real;
the inference was not established.
My own pre-registration named three ways the instrument could lie and
guarded two. The third -- "the guest may be frame-locked to its own
presentation rather than to the movie clock" -- is the one that occurred,
and a perfect 1.0000 is exactly what it produces: a triple buffer rotating
once per present gives run-length 1 at ANY frame rate. So the measurement
cannot separate a 30 fps guest decoding one movie frame per present from a
60 fps guest rotating a buffer per present.
The methodological error is the part worth keeping. I wrote the guard down,
saw a result so clean it had no tail, and read the cleanness as strength. A
clean result on an instrument whose key assumption is unguarded is not
confirmation -- the cleanness may be the failure mode's own signature. Both
guards I did build tested how the buffer was READ; neither tested whether a
buffer change means a decode.
What surfaced it: the draw log carries a per-frame gtick marker I had not
noticed. It is host time rescaled (Clock::QueryGuestTickCount is
host_tick_count * guest_tick_ratio, scalar 1.0), so it is a wall clock and
cannot be read as a rate -- but its SHAPE has no phase. Xenia locks vblank
to 60 Hz, and the present interval is ONE vblank 71.7% of the time and two
24.6%. A guest hard-locked to 30 fps presents every second vblank and would
put the mass at 2.
I am NOT replacing it with 120. Three routes now disagree: the withdrawn
movie cadence says 60, the vblank cadence says ~120, and
title-plate-delay's 120 declared units in 2.13 s measured twice to 6 ms
says ~56. Two of the three must be wrong and I do not know which.
Publishing 120 would repeat the mistake this commit withdraws.
The port is told to keep 60 for now, and told plainly that it is an
authored value rather than a measured one.
The settling experiment is named: hash the movie luma plane's CONTENTS per
present rather than its base address, which separates "the buffer rotated"
from "a frame was decoded".
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
