Encoding Profiles: 4K

Ultra-high-definition delivery changes the calculus in two directions. Frame area is four times larger, which raises the burden of every stage, and compression artefacts become individually less visible per pixel, which permits a coarser quality dial at the same subjective result. Both effects shape the anchors below.

UHD displays expose gradients and banding that HD surfaces mask

Codec selection at UHD

H.264 is workable at 4K but inefficient; the rate needed to avoid visible artefacts climbs steeply. HEVC Main10 is the practical mainstream choice, and AV1 is attractive where the player surface is controlled and encoder time is available.

Anchor settings

Mainstream UHDStreaming UHD

Parameter	Anchor	Notes
Codec	HEVC Main10	Efficiency with ten-bit precision
Quality dial	Dial 24	Grain tolerated with frame area
Preset	slow	Worth the time at this rung
Pixel format	4:2:0 10-bit	Gradient band reduction
Keyframe interval	96 frames	Four-second segments

Parameter	Anchor	Notes
Codec	AV1	Best efficiency in class
Quality dial	Dial 26 (AV1 scale)	Independent scale, re-measure
Preset	slowest available	Quality prioritised
Pixel format	4:2:0 10-bit	Compatible with surfaces
Keyframe interval	120 frames	Segment-friendly

Throughput reality

Processor-based encoding at 4K is expensive. Many operations split the tier: accelerated encoding for the lower rungs and processor-based encoding for the top rung only. That hybrid is described on the acceleration page.

Concern	Effect	Mitigation
Encode time	Multiplies with frame area	Accelerate lower rungs
Storage	Large files at high dials	Per-title ladder trimming
Banding	Visible on flat gradients	Ten-bit sampling
Device support	Narrower than HD	Keep an HD fallback pair

Do not assume a UHD rendition replaces an HD rendition in a ladder without measurement. The floor of your device population still needs the lower rung.

Compare with the 1080p profile and validate using the metrics framework.