Save Video with Custom Metadata (Dynamic)

The video counterpart to MetaSaverDynamic: twenty label/value pairs instead of ten, written as tags on the video container rather than a PNG chunk. If you're tracking more than ten things per render - seed, both prompts, CFG, sampler, model hash, a couple of LoRA weights, a batch note - this is the one with room for it.

What it actually wants wired in

Read the GitHub README before you build this and you'll expect an image-batch input with an fps field. That's not what's on the canvas. The current node takes a single video input - an already-encoded VIDEO object, the kind that comes out of whatever node in your graph assembles frames into a video - not raw frames. There's no fps to set here; whatever framerate the incoming video was built at is what you get. Treat this node as the last stop that re-saves an already-built video with your metadata stapled onto it, not as the thing that builds the video in the first place.

Inputs and outputs that matter

• video (VIDEO, required) - the encoded video from upstream.
• filename_prefix (STRING, default video/ComfyUI) - lands in a video/ subfolder of your output directory by default, not alongside your images.
• format - auto (match the source container) or force mp4.
• codec - auto (match the source codec) or force h264.
• meta_name_0…meta_name_19 / meta_value_0…meta_value_19 - twenty optional label/value pairs. meta_value takes any type - wire in an int, a string, a float, whatever's on hand. Blank pairs are silently skipped.

No output socket - terminal save node, same as the standard video variant.

Installing it

ComfyUI Manager: search "MetaSaver", install, restart - or manually:

cd ComfyUI/custom_nodes
git clone https://github.com/SorenWeile/ComfyUI_MetaSaver

then restart. The video nodes in this pack need PyAV (pip install av) to actually write the container tags; it ships with most ComfyUI distributions already, but if this node doesn't show up after a restart, that's the first thing to check in the console log.

Where it trips people up

The Dynamic-specific gotcha, straight from the author's own notes: pull the individual tags back out (not the JSON blob) and they come out prefixed with meta_ - a field you named cfg_scale reads back as meta_cfg_scale under ffprobe -show_format_tags or exiftool. If a script downstream expects the bare name, that prefix breaks it; read the structured custom_metadata JSON tag instead and you get your literal names back.

Otherwise the usual suspects: a meta_name with no value wired in (or the reverse) just vanishes rather than erroring, so check both halves of a pair before assuming something's broken. And if you're not actually filling more than ten fields, the plain MetaVideoSaver does the same job with less canvas clutter.