Video Export

The first thing to know is what this node is not. It is not a video writer. The description says it outright: "No movie codecs: use a video writer node." So if you came here to make an MP4, you want ComfyUI's own Save Video / video combine node, or the pack's Write nodes - not this one.

What it does instead is the finishing half of a VFX-style pipeline: pass frames through, encode them to an HDR signal, write a 32-bit float EXR sequence, or spit out a small GIF preview.

The four modes

mode is the whole node:

• passthrough - returns the frames. Useful as a labelled waypoint at the end of a graph.
• hdr_decode - runs the pack's Video HDR Decode internally (Reinhard tonemap, PQ out) and returns the HDR signal. Note the output is always PQ here: the tooltip for hdr_metadata_json says its peak_nits and gamut are used, "the eotf key is ignored."
• exr_sequence - writes files. 32-bit float, values unchanged, named <prefix>_<6-digit frame>.exr.
• preview_gif - writes <prefix>_preview.gif, clamped to 0–1 display-referred, and overwritten on each run.

Only the last two touch disk. That's a small but important detail: passthrough and hdr_decode are free of side effects, so you can leave them in a graph.

The settings

output_folder - empty means ComfyUI's output folder.

filename_prefix (default radiance_video) - the file-name stem, not a path.

fps (default 24) - GIF playback rate only; the frame duration written is 1000 / fps ms. It has no effect on the EXR sequence, which has no frame rate at all.

frame_offset (default 0, EXR mode only) - added to the frame number in the file names. This is the widget that makes the node usable in a real pipeline: you're writing frames 1001–1050 of a shot, not frames 0–49, and every downstream conform expects the real numbers. Set it once and your sequence drops into a timeline.

hdr_metadata_json (default {"peak_nits":1000,"eotf":"PQ (ST.2084)"}) - read only in hdr_decode.

Outputs: frames, frame_count and export_report.

Why EXR float matters

An EXR sequence written here keeps its values exactly - the tooltip says the write is unchanged, no colour conversion. That's the whole point of the format in this context: if you've gone to the trouble of expanding an SDR frame to a linear signal with highlights above 1.0, an 8-bit PNG throws it away, and even a 16-bit integer format quietly clamps and quantises it. Float EXR is what a Nuke or Resolve handoff expects, and it's what the pack's own Write nodes and the wider colour-management ecosystem are built around.

The GIF, by contrast, is a review artifact and only that. 256 colours, clamped, one file overwritten each run. It's genuinely useful for pasting a clip into a chat window, and it is not an output.

One thing you will not get in the EXR files: embedded generation metadata. That's a PNG convention (ComfyUI writes the prompt and workflow into PNG text chunks, which is what makes sharing a "workflow included" image work at all), and it doesn't travel into EXR here. If your delivery needs provenance, keep the PNG or a sidecar.

Install

1. ComfyUI Manager → search Radiance → Install → restart → refresh the browser.
2. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/fxtd-studios/radiance.git
cd radiance
python -m pip install -r requirements.txt

Windows portable users: run the pip line with python_embeded\python.exe. EXR writing is the reason the pack pulls in OpenEXR, OpenImageIO and tifffile, and its install.py checks the first two after a Manager install. On Python 3.14 there's no OpenEXR wheel, and EXR I/O falls back to OpenImageIO - which is a perfectly good path, but it explains why the dependency looks conditional in requirements.txt. RADIANCE_ALLOW_DOWNLOADS=0 disables model fetching generally; this node needs no models.

Gotchas

The GIF is silently replaced every run, so if you were keeping a few versions, you weren't. And with frame_offset at 0 your first frame is ..._000000.exr, which some tools will happily import at frame 0 and others will refuse to match to a 1001-based conform - set the offset and you never have that conversation.

Finally: EXR sequence plus a long clip equals a lot of disk. At 4K 32-bit float you're looking at tens of megabytes per frame, and the pack's own known-issues notes are candid that long clips hold many full-size buffers in RAM; plan the disk as well as the VRAM.