feat(render): opt-in --supersample (SSAA) for crisp moving text#94
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Render N× via Chromium deviceScaleFactor and Lanczos-downscale to the scene size at encode — the standard cure for anti-alias shimmer on moving text (the 2.5D affine perspective re-skews glyph edges every frame). On render/frame and the composition path; alias --ss, clamped 1-4, default 1 = off → byte-identical to today (determinism goldens unchanged). frameLoop threads deviceScaleFactor through withPage + adds downscalePng; encode.ts gains a downscale -vf scale. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Adds an opt-in
--supersample N(alias--ss) torender/frame: render at N× and Lanczos-downscale to the scene size, the standard fix for anti-alias shimmer on moving text. reframe's 2.5D perspective is an affine approximation that re-skews glyph edges every frame, so text under a card flip/tilt flickers subtly at 1×; supersampling gives the AA headroom to smooth it.How
frameLoop.ts—withPagetakes adeviceScaleFactor(default 1); threaded intocaptureIr/renderFrameAt/captureHtml. At N× the captured PNG is N×-sized. NewdownscalePng(buf,w,h)(ffmpeg Lanczos) for the single-frame path.encode.ts—encodeMp4gains adownscale?: {width,height}→ inserts-vf scale=W:H:flags=lanczos. Frames render N×, mp4 comes out at scene size.cli.ts/frame.ts/composition.ts— parse--supersample/--ss(clamp 1–4), thread through the IR/HTML/composition render paths + the single-frame downscale.Golden-safe / determinism
Default (no flag) =
deviceScaleFactor:1, no scale filter → byte-identical to today.determinism.test.tsunchanged and green. No IR/DisplayList change. N× is itself deterministic (fixed chromium flags + Lanczos + fixed encode).Verification
pnpm test— 446 pass incl. byte-identical determinism;pnpm typecheck+pnpm lintclean.reframe frame scene.ts --t 5.5 --ss 1vs--ss 2→ both output 1920×1080 (downscaled from 2×); the--ss 2frame has smoother text edges (and compresses smaller — less AA noise).Out of scope
batch --supersample(batch has its own render loop; a follow).player(live browser, N/A).🤖 Generated with Claude Code