FeiHou-Video Preview

"FeiHou-Video Preview" is the node you reach for when you've got a stack of frames and you're tired of clicking through them one at a time, or of polluting your output folder with a test video you only wanted to glance at for three seconds. It turns any IMAGE batch into a looping H.264 video that plays right in the node - and never, ever saves a file where you have to go delete it later. Feed it the frames from an AnimateDiff run, a Wan/Flux frame batch, an interpolation chain, whatever; what comes back is motion you can actually judge.

This is the classic ComfyUI gap: Preview Image shows you one frame, and if you want to see whether a batch actually animates smoothly, your standard answer has been the VideoHelperSuite Video Combine node, which is built to save files. People burn real time on that mismatch - the Reddit threads asking "can I just preview this without saving two video files" write themselves. FeiHou's answer is a lean sibling to that tool, and it lives in a pack that otherwise revolves around multi-image references, SAM3 cutouts, and Wan-style workflows - the author's whole thing is video-adjacent pipelines, so a preview-only encode slot fits right in.

How it works

Under the hood there's no trickery: the node calls a vendored copy of the VideoHelperSuite Video Combine backend (vhs_compat/ ships inside the pack) with save_output=False and a filename prefix of feihou_preview. The image batch gets encoded to video/h264-mp4 - pix_fmt=yuv420p, CRF 19, which is browser-safe and quality-fine for judging - and written to ComfyUI's temporary preview directory instead of your output folder. The frontend then drops a <video> element into the node that auto-plays the result on loop, muted by default with sound on hover, exactly like Video Combine V2's preview.

Because the whole VideoHelperSuite backend is vendored, you don't need ComfyUI-VideoHelperSuite installed at all for this to work. And since it has no outputs, ComfyUI treats it as an output node: it always runs, and the engine re-executes only the upstream nodes that feed it.

The inputs that matter

There are only three, and you'll typically touch two.

• images (IMAGE, required) - the frame batch to animate. That's the whole job.
• frame_rate (FLOAT widget, default 8) - how many frames per second the preview plays back. 8 is the low, preview-friendly default that keeps the temp file small; bump it to 12–16 if you're judging actual motion timing on a short batch. It's a plain widget, not a wire - no connection to route.
• audio (AUDIO, optional) - wire in audio if you want it muxed into the preview. Only relevant when you're checking something sound-aligned (a generated clip, a lip-sync pass), and it's genuinely optional.

One thing to know: this node takes decoded images only. If you're coming from a latent-based video pipeline and want VAE decode, format presets, and a real file at the end, that's the pack's other node, Video Combine 🎥🅥🅗🅢 V2 - this one is the "just show me" half of the pair.

Installing it

Search ComfyUI Manager for ComfyUI-FeiHou-Toolbox and install, or drop it in manually:

cd ComfyUI/custom_nodes
git clone https://github.com/FX-FeiHou/ComfyUI-FeiHou-Toolbox.git

Then restart ComfyUI and hard-refresh the browser. The pack declares zero pip dependencies - no requirements.txt, empty dependency list - so there's nothing extra to install. The H.264 encode leans on ffmpeg via the imageio-ffmpeg binary that ships with ComfyUI itself, falling back to a system ffmpeg if present.

Common issues & gotchas

The big one is a "missing node" moment: FeiHouVideoPreview is brand new - it landed after the README's own node table (still marked v2.9.4) was written, so the docs don't even list it yet. If you've installed the pack and don't see the node, you're on a stale version; update the pack from Manager or git pull, restart, and it'll show up under FeiHou Toolbox/video.

The other thing to internalize is that the preview is meant to be ephemeral. It lives in ComfyUI's temp directory, which gets cleaned up on restart, and that's by design - if you want the video to survive, that's Video Combine V2's job. Also don't panic if audio-bearing previews are silent at first: playback starts muted and unmutes on hover, which is a deliberate choice so a workflow run doesn't blast your speakers. If encode ever fails on a missing ffmpeg, that's almost always a broken VHS_FORCE_FFMPEG_PATH env override pointing at a binary that doesn't exist - clear it and let ComfyUI's bundled ffmpeg take over.