Workflow Vfx Pipeline

Workflow — VFX Pipeline

What: Handle VFX-grade media interchange. Color-managed ACES throughout, EXR as the float-linear format, USD for scene descriptions, clean handoffs to compositors and back to editorial.

Skills used

vfx-usd, vfx-openexr, vfx-oiio, ffmpeg-ocio-colorpro, ffmpeg-lut-grade, ffmpeg-probe, media-mediainfo, ffmpeg-hdr-color, ffmpeg-frames-images, ffmpeg-transcode, ffmpeg-mxf-imf, otio-convert.

Pipeline

Step 1 — Inspect EXR

vfx-openexr (exrctl header for channels / compression / chromaticities; exrctl info for multi-part / multi-view).

Step 2 — Inspect USD

vfx-usd (usdctl info for hierarchy; usdctl flatten to resolve LIVRPS composition).

Step 3 — Color config

export OCIO=/opt/aces/config.ocio. ffmpeg-ocio-colorpro list-transforms to confirm what's available. Core ACES spaces:

Step 4 — EXR → ProRes dailies

vfx-oiio (oiiotool color-managed ACEScg → Rec.709) OR ffmpeg-ocio-colorpro with the OCIO filter. ProRes 4444 XQ 12-bit for no clipping; 422 HQ 10-bit has YCbCr color loss vs EXR.

Step 5 — Plates for VFX vendors

LIN-LIN ACEScg EXR, ZIP compression, 16-bit half-float. Rec.709 JPEG proxies for review copies.

Step 6 — Ingest comps back

Verify color space = ACEScg. Check resolution, duration, frame count match. Round-trip to Rec.709 for review.

Step 7 — Cryptomatte extraction

exrctl list-parts → extract-part for crypto layers.

Step 8 — USD-driven render submission

usdctl reference to layout shots without opening Maya/Houdini. usdctl override attributes per shot.

Step 9 — Hand off to editorial

EXR ACEScg → Rec.2020 ST2084 ProRes 4444 XQ (HDR10 dailies) or straight to J2K IMF via ffmpeg-mxf-imf.

Step 10 — Back to NLE

Emit FCPXML via otio-convert for editor relink.

Variants

• Stereo 3D — exrctl info for multi-view, extract-view per eye, compose side-by-side via ffmpeg-360-3d.
• Deep compositing — exrctl deep-info on Z-layers, flatten deep → flat for ffmpeg compat.
• Environment maps — exrctl envmap cubemap ↔ latlong.
• Camera log → ACEScg — ARRI LogC / Sony SLog / RED Log mapped via OCIO.
• USD batch render — usdctl override per-shot, submit to renderer.

Gotchas

• ACEScg (AP1) vs ACES2065-1 (AP0). ACEScg for compositing (smaller gamut fits BT.2020). AP0 for archival wide-gamut only — DO NOT composite in AP0.
• OCIO config mismatch between tools breaks everything. oiiotool, ffmpeg, Nuke all consume the SAME config path. Always export OCIO=... from one source of truth.
• EXR chromaticities field is source-of-truth for color space. Absent = tools assume Rec.709/sRGB — WRONG for ACES. Always write chromaticities.
• ocio ffmpeg filter needs libOpenColorIO build. Verify: ffmpeg -filters | grep ocio.
• Rec.709 display output assumes sRGB gamma on monitors; broadcast uses BT.1886 (~2.4). Confirm target — OCIO has both Output - sRGB and Output - Rec.709.
• EXR compression choice: ZIP lossless slow (archive), ZIPS scanline ZIP faster, PIZ lossless great for natural, B44 lossy half-float, DWAA/DWAB high-quality lossy disk-cheap (dailies).
• Scanline vs tiled EXR. Scanline = default random access. Tiled needs tile-aware readers.
• Multi-part vs multi-channel. Multi-part = discrete "parts" with independent channels/compression/chromaticities — best for deep/crypto. Multi-channel = all AOVs in one part — simpler.
• Half-float 16-bit clips HDR above ~65504. Use 32-bit float for HDRI environment maps.
• Deep EXR has variable samples per pixel. Memory can balloon; all downstream tools must be deep-aware.
• USD LIVRPS composition order: Local, Inherits, VariantSets, References, Payloads, Specializes. Stronger layer always wins. resolve-info finds override culprits.
• USD references always load; payloads are lazy. Use payloads for large sets.
• USD variantSets are authoring-time, not runtime. variantSet lookStyle {blue,red,green} switches at authoring.
• USD file flavors: .usda ASCII editable, .usdc binary fast — NEVER hand-edit .usdc. Use usdedit or Python API. .usdz is a zipped bundle.
• USD defaults to centimeters. Many DCCs default to meters. 100× scale errors result.
• UsdSkel requires specific prim hierarchy (skeleton + animation + bindings). Validate with usdchecker.
• oiiotool --colorconvert requires $OCIO set. Without, fails silently.
• Frame sequences use 0-padded numbering (frame_0001.exr). frame_1.exr ≠ frame_0001.exr in glob matching. Rename first if inconsistent.
• OIIO TextureSystem caches aggressively. Weird behaviour → oiiotool --invalidate.
• iinfo -v on 4K EXR is fast; on 16K EXR it reads the whole file. Use --stats for summary only.
• ProRes --profile:v 4 = 4444 (12-bit RGBA). 422 HQ 10-bit YCbCr = color loss from EXR source.
• IMF from VFX: J2K encoding of float EXR → int12/int16 loses dynamic range. Author EXR → RGB int16 → J2K.
• Nuke "DPX" ≠ SMPTE DPX. Nuke adds a variant some downstream tools reject. Use oiiotool for standard DPX.

Example — ARRI LogC plate → ACEScg comp → HDR10 IMF

ARRI footage LogC v3 → OCIO transform to ACEScg EXR (16-bit half ZIP) → handoff to comp → ingest comp EXR sequence → oiiotool color-convert ACEScg → Rec.2020 ST2084 ProRes 4444 XQ 12-bit → ffmpeg-mxf-imf J2K IMF.

Related

• workflow-hdr — HDR mastering details.
• workflow-broadcast-delivery — IMF / MXF OP1a packaging.
• workflow-editorial-interchange — OTIO round-trip to the editor.