Files
hyperframes/packages/engine/src
James RussoandClaude Opus 4.7 ffc06827c4 fix(engine): auto-normalize VFR video inputs to CFR before frame extraction (#360)
* fix(engine): auto-normalize VFR video inputs to CFR before frame extraction

Screen recordings (macOS ScreenCaptureKit, QuickTime, phone videos) are
commonly variable-frame-rate. When such inputs hit the extractor's
`-ss <start> -i <video> -t <dur> -vf fps=N` pipeline, the fps filter
can emit fewer frames than requested — for a 4-second 30fps segment
starting mid-file, the output was ~90 frames instead of 120.

`FrameLookupTable.getFrameAtTime` returns null for out-of-range indices,
so the compositor held the last valid frame and the user perceived the
video as freezing. This matches the bug report from an X community post
where a user said "all of them freezes" on their screen recording scenes.

The engine already detects VFR via `metadata.isVFR` in ffprobe.ts but
never acted on it — the compiler only logged a warning. This change
mirrors the existing SDR→HDR normalization pattern: when a source is
detected as VFR, re-encode only the used segment with
`-fps_mode cfr -r <fps> -preset fast -crf 18` before extraction.

Scoping the re-encode to `[mediaStart, mediaStart+duration]` means a
30-second clip cut from a 60-minute screen recording pays ~1s of
transcode cost, not 18s. Benchmarked locally:

  Baseline (current):         32-39% duplicate frames, 25% frame-count
                              shortfall on mid-file segments.
  Tier 1 (flag changes only): ~same — fps filter issue is not flag-fixable.
  Tier 2 (CFR preflight):     1.7-6% duplicate frames, correct frame
                              count in every scenario tested.

The compiler warning that previously told users to manually re-encode
is downgraded to `console.info` since the engine now handles it.

— Rames Jusso

* refactor(engine): clean up VFR normalization loop after review

- Drop the `vfrNormDirCreated` flag; `mkdirSync({recursive:true})` is
  idempotent and cheap.
- Don't re-wrap the `VFR→CFR conversion failed` prefix — `convertVfrToCfr`
  already throws a message with that label; adding it again in the catch
  produced "VFR→CFR conversion failed: VFR→CFR conversion failed (exit 1)".
- Shorten the Phase 2b header comment; the function docstring above
  `convertVfrToCfr` already explains the failure modes and rationale.
- Note which frame windows the VFR fixture's select filter drops so the
  magic numbers are scannable.

No behavior change; 311/311 engine tests still pass.

— Rames Jusso

* test(engine): add VFR regression unit tests

Adds a describe block that synthesizes a VFR fixture via ffmpeg and asserts
the extractor produces the expected frame count (no shortfall) and no long
runs of duplicate frames — the user-visible "frozen screen recording"
symptom. Covers both a mid-file segment and the full-file case.

Guarded with describe.skipIf(!HAS_FFMPEG) because the CI Test job on
ubuntu-24.04 and the Windows test-windows job don't install ffmpeg. The
producer-level regression test in packages/producer/tests/vfr-screen-recording/
runs inside Dockerfile.test (which has ffmpeg) and is the primary CI signal
for this bug; these unit tests are supplementary coverage for local and
any ffmpeg-equipped CI environment.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test(producer): add vfr-screen-recording regression test

End-to-end CI regression coverage for PR #360 via the existing
regression-harness: renders a 3s composition containing a real macOS
ScreenCaptureKit clip (r_frame_rate=120, avg≈36fps) seeked to
mediaStart=1, then PSNR-compares against a committed output.mp4.

Fixture src/clip.mp4 (108 KB) is a 5-second excerpt downscaled to 480×332
with -fps_mode passthrough to preserve the VFR timestamps. Content is the
public hyperframes OSS repo root page — see NOTICE.md for provenance.

With the fix applied, all 100 PSNR checkpoints pass. With the fix reverted,
66 of 100 fail (PSNR drops from ~43 dB to ~20 dB in the duplicate-frame
windows). Tagged "regression,video,vfr" so it runs in the fast shard
of .github/workflows/regression.yml automatically.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test(producer): regenerate vfr-screen-recording baseline in Docker

The committed golden output.mp4 was initially rendered on the host machine;
CI runs the renderer inside Dockerfile.test with a different Chrome +
ffmpeg build, producing pixel-level drift that failed PSNR at 54/100
checkpoints (~20 dB vs 41 dB in the VFR sparse-content windows). Both
renders are valid — the VFR source has inherent sampling ambiguity in
static segments, and different Chrome/ffmpeg builds make different valid
choices.

Regenerated the baseline via `bun run docker:test:update vfr-screen-recording`
so it matches the Docker environment CI actually uses. Matches the flow
the existing sub-composition-video, hdr-pq, etc. baselines were captured
with.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* docs: document that producer test baselines must be captured in Docker

Hit this 2026-04-21 with the vfr-screen-recording regression test:
host-generated output.mp4 baseline tripped 54/100 PSNR checkpoints in CI
because Chrome + ffmpeg drift between the host and Dockerfile.test.

Document the `bun run --cwd packages/producer docker:test:update <name>`
flow so future contributors don't repeat the mistake.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-21 12:14:23 -07:00
..