Editor: Supports video rendering termination

[ycw]

fix: #28454

With this PR, users can now terminate video rendering by closing the popup window

Details:

• Checks popup window .closed before each FS (writefile) APIs, short-circuit if value is true (suggested by @aardgoose), in this case no further processing.

• Calls ffmpeg.exit() on popup window unload, in order to terminate ongoing .run() (tested by @Mugen87), in this case no further processing.

  • NOTE: Calling ffmpeg.exit() won't stop queued FS (writeFile) calls, instead this is guarded by checking popup window .closed)

  • NOTE: There will be some errors logged in the console after calling ffmpeg.exit(), these errors can't be caught in sidebar.project.video.js because they were raised from a worker spawned from ffmpeg.js:

    screenshot

    

• Unlinks out.mp4 from ffmpeg.FS when teardown

• Ensures that player.dispose() will be called no matter ffmpeg.exit()-ed or not

• Handles setProgress with 2 special cases:

  1. ratio sometimes be Infinity when multi videos are being rendered at the same time
  2. ffmpeg.wasm/issues/178 (*I can't reproduce this though)

[mrdoob]

Before is twas possible to render multiple videos at the same time.
Now that only one video is created I guess it's no longer possible?

[ycw]

render multiple videos at the same time.

It's still support because a new ffmpeg context is created per 'RENDER' click.

BTW, progress callback ratio can sometimes be NaN, or Infinity when rendering multi video at the same time, this special case wasn't handled by current editor. This PR handled this case now.