SaveWEBM_motorway_edition

When your image batch is a real video - dozens or hundreds of frames - APNG and animated WEBP stop being practical, and this is the node you want. SaveWEBM_motorway_edition clones ComfyUI's built-in SaveWEBM, which encodes your frame batch into an actual WEBM video file using ffmpeg under the hood. This is the format that keeps 24 fps of video from being 24 full images stacked in a row; temporal compression makes it a fraction of the size. If you're doing AnimateDiff, video models, or frame-interpolation work in ComfyUI, WEBM is the standard output format and this is that output, riding the Motorway bus.

The one thing to know before you hit "Queue": WEBM needs ffmpeg to be available, and which codecs work depends on your ffmpeg build. That's true of the stock node too - this pack doesn't change it - but it's the most likely place a beginner gets stopped. No images come back out of a save node; the file lands in ComfyUI/output/, and like the other save clones here, it isn't flagged as an output node, so check the output folder rather than the canvas.

The widgets:

• codec - vp9 or av1. VP9 is the broadly compatible default. AV1 compresses better but needs an ffmpeg build with AV1 support and encodes slower; if you get a codec error, your ffmpeg probably lacks it.
• fps (default 24) - playback frame rate. Match this to how your frames were generated (or intended) - 24 for standard video, 30 for smoother motion.
• crf (default 32, 0–63) - the quality/size dial, and the author's tooltip says it plainly: "Higher crf means lower quality with a smaller file size, lower crf means higher quality higher filesize." 32 is a reasonable default; go lower (18–24) when quality matters.
• filename_prefix (default ComfyUI) - output base name, supports date/formatting tokens.

The frames are pulled from the bus by key - INPUT_images_key (default images) - so type the key your earlier nodes used to park the image batch.

Installing it

Part of ComfyUI_agilly1989_motorway. ComfyUI Manager: search ComfyUI_agilly1989_motorway, install, restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/agilly1989/ComfyUI_agilly1989_motorway

No Python dependencies and no model files, but you need ffmpeg on your PATH - the same requirement as the stock SaveWEBM. If you installed ComfyUI via the one-click bundle, it's already there.

The catch

Pack-wide caveats apply: release 1.1.7 ships with the clones disabled (uncomment the two ClonedNodeMapping lines in custom_nodes/ComfyUI_agilly1989_motorway/__init__.py, restart), and save/output nodes are the category the author's README - which opens "BIG BROKEN WITH ASYNC WILL FIX WHEN I GET THE TIME/MOTIVATION" - warns may not work. For dependable video output, stock SaveWEBM is the safe choice; this one is for keeping the encode step on the bus.