凤希AI - 视频预览

FxAiVideoPreview ("凤希AI - 视频预览") is a display node: you hand it a video file path (a STRING, not frames) and it shows that video in the UI. It's the pack's answer to a gap in stock ComfyUI - stock nodes preview image tensors, but there's no native node that says "here's an mp4 on disk, play it." This one plugs that hole at the end of every render/merge/split path.

What it's for

The pack's video generators return a 视频文件路径 string, the merger returns a 视频本地路径 string, the splitter returns an output folder. None of those are tensors - they're paths to files on disk. A normal Preview Image can't show them, and drag-and-drop won't load them either. This node takes that string and makes it visible, so you can check a segment before committing to the next loop iteration without leaving ComfyUI.

It's an output node (OUTPUT_NODE = True) with no outputs - it terminates a branch and shows its UI widget. The only input is 视频文件路径 (STRING, default empty). Wire the path output of any generator or merger into it, and the frontend's custom video widget takes over.

The honest take

This is the kind of node that feels pointless until you've spent twenty minutes hunting for the file a merger just produced. Once you realize the pack doesn't save to output/ (it saves to ComfyUI/fxai/video/...), a preview node wired to the path becomes your map. Put one after every render step in a long workflow and you catch a bad segment at the moment it's produced, not after the whole batch finishes. The pack markets this as "实时预览分段成片，提前排查画面BUG" - preview segments early, catch bugs early - and that's a legitimately good workflow habit.

The caveats

• Garbage in, nothing out. If the path is empty, points at a file that doesn't exist, or the browser can't reach that filesystem location, you get a blank widget. No error, no placeholder. It only displays - it never validates. Wire the path from a generator/merger rather than typing it by hand.
• Because it's a plain string sink, it's happy to preview anything a path output produces - including a splitter's folder if you feed it that (which won't play; folders aren't videos). Feed it file paths, not directories.

Install

Same pack, same install:

cd ComfyUI/custom_nodes
git clone https://github.com/fxai666/fxai-toolkit

Restart ComfyUI, or use ComfyUI Manager and search "fxai-toolkit". Zero dependencies beyond the pack's JS frontend - there's no decoding happening in Python at all; the video plays in the browser.