UGTK / Toolkit / Utility Systems / Video View System Completed

Video View System

Summary

A VideoPlayer companion that, on WebGL, downloads (or reuses a cached) remote video through a .jslib plugin and plays it back from a Blob URL; in Editor/Standalone it falls back to direct URL streaming. It exposes UnityEvents for the cache, ready, play-started and error stages.

Modules Dependencies

This module has no hard UGTK dependencies. It uses Unity's UnityEngine.Video and its own bundled plugin Plugins/WebGL/Mn_WebGLVideoCache.jslib.

Setup

Drop the Video prefab into the scene — a VideoPlayer with Mn_WebGLVideoPrefetcher already attached:

How To Use

Put a Unity VideoPlayer on a GameObject and add Mn_WebGLVideoPrefetcher (a Video prefab is provided). Without a VideoPlayer the component logs an error and disables itself.
Set the source: either the sourceUrl field (HTTP/HTTPS) or leave it empty to use VideoPlayer.url. SetSourceUrl(string) sets it at runtime.
On Start (or by calling Begin()) the cache → prepare → play cycle runs:
WebGL build: calls WebGLVideoCache_DownloadOrGet(url, goName); the plugin calls back OnWebGLVideoBlobReady(blobUrl) (fires OnVideoCached), which prepares the player from the Blob; OnWebGLVideoBlobError reports failures.
Editor/Standalone: sets VideoSource.Url and calls Prepare() directly.
On prepareCompleted it fires OnVideoReady and auto-Play(); started fires OnPlayStarted. Any failure fires OnError(string) and logs it.
On WebGL, ClearPersistentCacheForUrl() clears the persistent Cache-Storage entry for the resolved URL (use when you replace the server file). OnDestroy releases the plugin reference to the original URL.

The player is configured conservatively for WebGL: playOnAwake = false, waitForFirstFrame = true, skipOnDrop = true.

Good to know:

The whole point is WebGL. In the editor and in a standalone build the component just streams the URL, so a bug in the caching path will only show up in the browser: test the real build.
A remote video needs CORS. The plugin fetches the file with JavaScript: without the right Access-Control-Allow-Origin header on the server the download fails and you get OnError — streaming the same URL directly might still have worked, which makes it confusing.
The cache is persistent (Cache Storage). Replacing the file on the server without changing its name leaves returning players on the old video: call ClearPersistentCacheForUrl() or version the URL.
Browsers block audible autoplay. Play() right after prepare works muted; with audio it needs a user gesture first.
No VideoPlayer sibling = the component logs an error and disables itself — it does not throw.

Testing Scene

Open VideoViewScene in the module's Debug/ folder.

What to do, in order:

Play a video from a local file.
Play one from a URL.
Simulate the browser's failure callback from the inspector.
Replace the file on the server and play again without clearing the cache.

Step 3 exists because the error path needs a URL that fails in the right way, which in practice means it never gets tested. Step 4 shows the persistent cache doing its job too well: viewers keep seeing the old video until ClearPersistentCacheForUrl is called.

The recording is the demo playing its bundled clip: press Play and the picture runs. The display in the scene is deliberately small, so what the recording shows is that frames are arriving - the only thing worth checking in the editor, since the interesting failures all belong to the browser and appear in steps 2 to 4 below.

Technical Info

Mn_WebGLVideoPrefetcher: MonoBehaviour (requires a sibling VideoPlayer). Resolves the source URL, drives cache/prepare/play, wires VideoPlayer events, and exposes OnVideoCached / OnVideoReady / OnPlayStarted / OnError UnityEvents plus Begin, SetSourceUrl, ClearPersistentCacheForUrl. WebGL native calls go through [DllImport("__Internal")] into Mn_WebGLVideoCache.jslib.