Everything here is evidence and state, not behavior: the shipped operating point
is untouched at 512 px / 12 fps / noise_std=0.15.
The carrier was downloaded and its sha256 matched the manifest, so its properties
are now measured rather than assumed: 1920x1080 at 24 fps with an AAC audio track.
Those three fields go into the two 2026-07-31 rows, which could not previously
tell a reader what the downscale factor even was.
The geometry prize is measured end to end for the first time. Against the
untouched source, 1024 scores +3.46 dB over the shipped 512, while the entire
noise_std axis is worth 1.92 dB. Two readings that the table alone hides are
recorded with it: the temporal residual IMPROVES with resolution, because the
shared noise field lives on the latent grid and is four times finer relative to
the frame at 1920; and the frame-rate arm cannot be judged by these metrics at
all, since they price its cost and not the smoothness it buys.
Two findings that outrank the quality question. The certified row does not
reproduce -- a rerun of the same configuration on a different device and dtype
gives a different hash and different metrics, and the manifest records neither.
And the pipeline copies audio byte for byte while stripping every metadata
marker, so it can emit a file our own detector calls clean with an untouched
Google-generated audio track inside it. The mechanism is proven on two carriers;
whether that audio carries a mark the verifier reads is not, and only the oracle
can say.
The six prepared oracle submissions were never run: file upload to the verifier
failed at the tool level. Their artifacts are gone with the scratch directory,
which is the intended lifecycle for generated media, and the document says what
rebuilding costs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The shipped profile was certified by one oracle row, but only noise_std was
pinned: long_side and fps -- two thirds of what the verifier was actually shown
-- could move with a green suite. The test now derives the pin from
data/evaluations/video-synthid-oracle.csv, so a default without a certifying row
fails.
The certified profile is a perturbation-to-signal ratio, not a bare noise_std.
sd-vae-ft-mse publishes no scaling_factor key, so 0.18215 comes from the
AutoencoderKL class default under an upper-unbounded diffusers pin. The loader
now gates that value, carries it on VideoVaeRuntime, and passes it into encode
and decode so the validated value is the applied value. video_synthid_sweep.py
loads through the same function: the harness producing the certified rows was
the one path exempt from the gate it exists to feed.
psnr_db is measured against the already-resized frame and before the encoder, so
it cannot see the downscale, the decimation, or the codec, and no in-loop metric
can. scripts/video_fidelity_probe.py scores the delivered file end to end,
streaming the way the engine does and sharing its frame-selection rule rather
than copying it -- a frame-count check cannot catch a rule that reorders frames
without changing how many.
The manifest gains source geometry, vae, track, verbatim verdict and session
fields. The two 2026-07-31 rows keep them empty: they were never recorded and
are not recoverable. Verdicts now have four states, because the verifier's
unclear reading logged as not_detected is the silent regression the manifest
exists to prevent.
docs/video-synthid-quality-research.md records the research behind this: the
noise axis is worth about 2 dB and is nearly exhausted, resolution is the real
prize but is an uncertified destruction axis rather than a free win, and every
proposed autoencoder swap was refuted. First local measurements included.
Verified: engine output is byte-identical before and after the refactor on a
locally built clip, at noise_std 0.00 and 0.15.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Victor Kuznetsov