4K Nature — 1/4.4 of the original.

Same 20-second 4K30 nature timelapse. The right side is NormH.264 at 25 MB, down from 110 MB. Both auto-play below — judge for yourself.

Heavy demo (~135 MB total) — on metered connections, click each video's play button instead of relying on auto-play.

Source — H.264 4K30 · 110 MB · ~45 Mbps
4k_nature_h264_source.mp4 · 20.35 s · high-bitrate H.264 master

NormH.264 — H.264 4K30 · 25 MB (−77.3%, 1/4.4)
4k_nature_norm_h264.mp4 · VMAF 80.47 / VMAF min 68.90 · same H.264, plays everywhere

110 MB → 25 MB

VMAF 80.47, VMAF min 68.90 — visually-identical band on natural-content timelapse. Same H.264 codec, same 4K30, plays unmodified on every device.

Notice the playback itself. The source on the left (110 MB) buffers, stalls, hesitates on most connections. NormH.264 on the right (25 MB) plays smoothly the moment you load the page. The compression delta is also a delivery and UX delta — viewers do not need to know about VMAF; they feel the difference as “starts faster, never stutters”.

Why this is hard

4K nature timelapses are texture-heavy: leaves, grass, water, sky gradients, sun rays. There is no flat region for an encoder to give up cheaply. Plain H.264 at this quality routinely sits at 40–50 Mbps. NormMAP's commutator-norm hint tells libx264 where the eye actually pays attention, so bit budget collapses on perceptually-quiet blocks while preserving the busy ones.

Spec

Source	4K-14690379_3840_2160_30fps.mp4 (open-web 4K nature timelapse)
Resolution	3840 × 2160 (4K UHD), 30 fps, 20.35 s, 610 frames
Source codec	H.264 (yuv420p), bitrate ~45 Mbps
Output codec	H.264 (yuv420p), via NormH.264 v0.3.2 (slime-2 preset)
NormMAP config	commutator-norm block-level bit allocation, libx264 ROI side-data path, aggressive bias
VMAF mean	80.47 (visually-identical band: VMAF 80–90)
VMAF min	68.90 (worst frame on a heavy-detail moment)
Size delta	−77.3% (1/4.4) versus 4K H.264 source
Decode compatibility	H.264 — every browser, device, set-top, including Safari iOS without polyfills

See more: CityHall 4K compare (1/2 from already-AV1) · 30-day trial →