Workflow Hdr

Workflow — HDR

What: Author, transcode, tone-map, and deliver HDR content across every major standard without metadata loss.

Skills used

ffmpeg-hdr-color, hdr-dovi-tool, hdr-hdr10plus-tool, hdr-dynmeta-docs, ffmpeg-ocio-colorpro, vfx-oiio, ffmpeg-probe, media-mediainfo, ffmpeg-transcode, ffmpeg-hwaccel, ffmpeg-mxf-imf, media-shaka.

Pipeline

Step 1 — Probe

ffmpeg-probe (moprobe --color) captures: color primaries (bt709 / bt2020), transfer (bt709 / smpte2084 / arib-std-b67), matrix, range, MaxCLL / MaxFALL, DoVi RPU SEI, HDR10+ SEI.

Step 2 — SDR → HDR (up)

ffmpeg-hdr-color sdr-to-hdr --target hlg|hdr10 with a synthetic MDC. Inverse tone-mapping is creative — use sparingly; real HDR grading is preferable.

Step 3 — HDR → SDR (down)

ffmpeg-hdr-color hdr-to-sdr --algo <hable|mobius|reinhard|bt2390|bt2446a|bt2446c|aces>. Try bt2446a first — ITU-standard, predictable.

Step 4 — Cross-format HDR conversion

Between HDR10 and HLG, ALWAYS via the linear-float sandwich:

zscale=t=linear → format=gbrpf32le → zscale=t=<new_transfer>:p=<primaries>:m=<matrix>

Missing the float32 step silently clips highlights.

Step 5 — Dolby Vision RPU ops

hdr-dovi-tool:

• extract-rpu from HEVC
• convert --mode 2 (profile 7 → 8.1 for streaming)
• editor for L1/L2/L8 metadata edits
• inject-rpu into fresh HEVC

For HDR10 → DoVi uplift, dovi_tool generates a synthetic RPU.

Step 6 — HDR10+ metadata ops

hdr-hdr10plus-tool:

• extract JSON from HEVC
• author / edit per-scene brightness JSON
• inject into HEVC

Or inline at encode: -x265-params "dhdr10-info=metadata.json".

Step 7 — Author final HEVC

libx265 with:

• hdr-opt=1
• repeat-headers=1 (streaming)
• master-display=G(...)B(...)R(...)WP(...)L(...) (in x265 units: 0.00002 for chromaticity, 0.0001 for luminance)
• max-cll=<MaxCLL>,<MaxFALL>
• -pix_fmt yuv420p10le (mandatory; 8-bit = banding)
• -tag:v hvc1 for MP4 Apple compat

Step 8 — AV1 Dolby Vision (alternative)

libaom-av1 or libsvtav1 at profile 10.

Step 9 — Deliver / wrap

MP4 (hvc1 tag), MKV, or J2K IMF via ffmpeg-mxf-imf. DASH/HLS packaging via media-shaka.

Variants

• DoVi-only sensible — profile 8.1 single-layer HDR10-base (most OTT accepts). Extract P7 RPU → convert to 8.1 → re-encode stripping old → inject fresh.
• Dual delivery (HDR10 + HDR10+ + DoVi + HLG + SDR) — start from linear EXR or ProRes 4444. Encode HDR10 base, inject HDR10+ JSON, inject DoVi RPU, encode HLG separately, SDR via tone-map.
• YouTube HDR — accepts HDR10 / HDR10+ / HLG / DoVi. Best results from VP9 or AV1.
• Apple HLS HDR — HEVC fMP4, hvc1 tag, proper color tags.
• HLG live broadcast — backward-compat 100-nit SDR window on non-HDR displays.

Gotchas

• HDR metadata lives in NAL units inside HEVC. Any re-encode strips unless explicitly preserved. -c:v copy when possible; otherwise extract → encode → re-inject.
• Dolby Vision RPU = SEI NALs 62/63 with Dolby T.35 UUID.
• HDR10+ metadata = SEI 0x4 with Samsung T.35 UUID.
• Stripping NALs is easy; re-injecting correctly is hard. Always use dovi_tool / hdr10plus_tool — never hand-craft.
• Profile 7 dual-layer has TWO video layers (BL + EL). Some extractors choke. dovi_tool is canonical.
• master-display x265 unit trap: chromaticity in 0.00002 units (0.6 = 30000), luminance in 0.0001 units (1000 nits = 10000000). Wrong units = invalid SEI.
• max-cll=1000,400 (MaxCLL, MaxFALL) — single pair, NOT an array.
• repeat-headers=1 mandatory for streaming. Without, first segment has headers, subsequent don't → mid-stream joiners break.
• hdr-opt=1 enables HDR optimizations but auto-sets NOTHING. You still need explicit colorprim, transfer, colormatrix.
• aom-av1 flags differ — --color-primaries etc. via -svtav1-params.
• BT.2100 PQ (ST 2084) and HLG (ARIB STD-B67) are INCOMPATIBLE transfer curves. HLG-display of PQ = washed. PQ-display of HLG = dim.
• PQ = absolute luminance (100 nits = 100 nits on screen). HLG = relative (100% = display peak, typically 1000 nits).
• HLG has an OOTF (optical-optical transfer function) that shifts gamma based on display peak. Tone-mapping to SDR must respect it.
• tonemap_opencl + libplacebo are GPU-accelerated — much faster than CPU for 4K. Needs libplacebo-enabled ffmpeg build.
• MP4 HEVC tag must be hvc1 for iOS/Apple. hev1 works elsewhere; Apple rejects.
• Netflix IMF wants J2K video with HDR10+/DoVi metadata as a SIDECAR XML, not inline.
• Dolby Vision MEL profile 8.4 uses HLG base (different workflow from 8.1 PQ base).
• YouTube re-encodes HDR uploads. Don't expect bit-for-bit preservation.
• libx265 defaults to yuv420p (8-bit). MUST explicitly set -pix_fmt yuv420p10le for HDR — without it = banding.
• EXR linear ACEScg → PQ/HLG path: zscale=t=linear is CRITICAL between ACEScg and display-referred. Without it, gamma compression doubles.
• ACES RRT+ODT is NOT a naive tone-map. Use OCIO for canonical ACES RRT path.

Example — HDR10+ with DoVi P8.1 dual delivery

Source HEVC HDR10 base → hdr-dovi-tool generate synthetic RPU P8.1 → hdr-hdr10plus-tool author per-scene JSON → encode fresh HEVC 10-bit with hdr-opt=1 repeat-headers=1 master-display=... max-cll=1000,400 → dovi_tool inject-rpu → hdr10plus_tool inject → MP4 -tag:v hvc1.

Related

• workflow-broadcast-delivery — IMF / MXF packaging for OTT delivery.
• workflow-vfx-pipeline — ACES EXR sources feeding HDR master.
• workflow-streaming-distribution — packaging HDR for HLS/DASH.