EXR Converter

Desktop app and CLI for converting between video and OpenEXR sequences with OpenColorIO color management and built-in slate rendering. Uses PyAV for decode/encode, OpenImageIO for EXR I/O, and PySide6 (QPainter) for the GUI and slate compositing.

Targets the VFX Reference Platform CY2026: Python 3.13, Qt/PySide 6.8, OpenColorIO 2.5, OpenEXR 3.4, NumPy 2.3.

Downloads

Platform	Download
Windows x64	Installer (.exe)
macOS Apple Silicon	DMG
macOS Intel	DMG
Linux x86_64	AppImage

All release artifacts are signed with Sigstore Cosign — see the releases page for verification instructions.

macOS Gatekeeper: Like most open-source macOS apps distributed outside the App Store, these builds are not Apple-notarized. On first launch macOS may block the app — right-click it and choose Open, or run xattr -cr "/Applications/EXR Converter.app". This is a standard macOS security prompt for apps without a paid Apple Developer signature.

Tech stack

Layer	Notes
Language & tooling	Python 3.13, uv for deps and runs, Ruff in CI, Nuitka for standalone bundles
UI	PySide6 (Qt 6.8), Nuke-inspired dark theme
Imaging & color	OpenImageIO (oiio-python), OpenColorIO 2.5 display/render transforms with a scene-linear working space (resolves to the active config's scene_linear role) for all overlay compositing. Bundles the official ACES Studio Config v4 (from ASWF OpenColorIO-Config-ACES, BSD-3-Clause) which includes dozens of camera IDTs including Apple Log (iPhone 15/16 Pro cinematic / ProRes Log), ARRI LogC3/4, RED Log3G10, Sony S-Log/Venice, Canon, DJI, and many more.
Video & sequences	PyAV (FFmpeg bindings) for video I/O, fileseq for frame sequences & ranges
Slate / burn-in / watermark	Native QPainter preview and offscreen capture (no embedded browser); burn-in and watermark are linearised into the working space and alpha-composited per-frame, then OCIO-transformed to display before encode

CI runs on GitHub Actions; releases publish binaries for Linux, macOS (Apple Silicon + Intel), and Windows.

Screenshot

GUI

uv run python main.py

No subcommand — opens the main window. OCIO resolution follows $OCIO when set, otherwise the bundled ACES Studio Config v4 (ACES 2.0) — the official rich config from the Academy Software Foundation containing a huge set of camera input transforms including Apple Log (for iPhone 15/16 Pro cinematic video and ProRes Log), ARRI LogC3/4, RED, Sony, Canon, DJI and many others, plus modern ACES Output Transforms and displays.

Common camera source names (when using the default ACES Studio config): "Apple Log" (or "apple_log", "iphone log"), "ARRI LogC3 (EI800)", "Log3G10 REDWideGamutRGB", etc. The UI source picker groups them under families like Input/Apple, Input/ARRI, etc. You can also pass --ocio /path/to/your.config.ocio or choose other built-ins / custom in the UI.

Enable the Prepend slate checkbox to add a 1-frame slate image before the converted output.

CLI

Use the video2exr or exr2video subcommand.

Video → EXR

uv run python main.py video2exr -i clip.mov -o ./exr_out/

EXR → video

uv run python main.py exr2video -i "./plate.####.exr" -o review.mov --fps 24

Common options:

Option	Applies to	Notes
--ocio PATH	both	OCIO config file (overrides $OCIO)
--src / --dst	both	OCIO display / scene color space names
--workers N	both	0 = auto, 1 = single-threaded
--scale FACTOR	both	e.g. 0.5 for half resolution
--exr-compression NAME	video2exr	e.g. dwaa, zip, none (see --help)
--codec KEY	exr2video	e.g. prores, h264, prores_4444, dnxhr_hq, ffv1

Run uv run python main.py video2exr --help or exr2video --help for the full list.

Requirements (running from source)

• Python 3.13
• uv (recommended) or another PEP 621-compatible installer

git clone https://github.com/derek-rein/vfx-tools.git
cd vfx-tools
uv sync

Building from source

Prerequisites: Python 3.13, uv, and a C compiler (Xcode CLT on macOS, MSVC on Windows, gcc on Linux).

uv sync
make bundle

This uses Nuitka to produce a standalone distributable:

Platform	Output
macOS	dist/EXR Converter.app
Linux	dist/exr_converter (single binary)
Windows	dist\main.dist\ (folder with exr_converter.exe + dependencies)

Nuitka will auto-download ccache on first run. See the Makefile for the full set of flags.

Development

Target	Purpose
make run	Start the GUI
make lint / make fmt	Ruff check / format
make resources	Regenerate src/rc_resources.py from resources.qrc (needed after icon changes)
make bundle	Nuitka standalone bundle under dist/
make clean	Remove all build artifacts

Icons live under public/ (icon.icns / icon.ico / icon.png).

Releases

Tags use plain semver: v1.2.3. Pushing a tag runs .github/workflows/release.yml and publishes a GitHub Release with Linux AppImage, macOS DMGs (ARM64 + Intel), and a Windows installer.

make help
make release PART=patch        # bump + commit + tag + push (triggers Release workflow)
make release PUSH=0            # local only; push branch + tag yourself when ready

CI for lint: .github/workflows/ci.yml.

License

MIT — see LICENSE.

derekvfx.ca