Support WebM videos with alpha channel/transparency

[htangidnerd]

Describe the project you are working on:

We are working on 2d displays for casino floor games. It is designed to show current game state, event history and result trends.

Describe the problem or limitation you are having in your project:

We want to use video for a full screen overlay to play a pre-rendered animation but the current godot video player does not support alpha channel. Currently we are using AnimatedSprites for this. However as we add more animations, memory is becoming an issue.

Describe the feature / enhancement and how it helps to overcome the problem or limitation:

The video player should detect and process alpha channel data encoded into the video.

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:

This feature should be seamless to the user as it would only function if there is alpha channel in the video data.

If this enhancement will not be used often, can it be worked around with a few lines of script?:

Should not impact cases of video playback without alpha channel.

Is there a reason why this should be core and not an add-on in the asset library?:

This makes more sense as a built in feature for the core video player.

related link. 18337

[Calinou]

Note that WebM support may be moved to a GDNative plugin in the future, as it has proven difficult to work with in core: https://github.com/godotengine/godot/issues?q=is%3Aissue+is%3Aopen+webm+label%3Abug

In the meantime, depending your needs, you may be able to use a chroma keying ("green screen") shader.

[fire]

Another group had better success using ffmpeg's WebM (video) support in ffmpeg.

https://github.com/kidrigger/godot-videodecoder

However due to lack of experience kidrigger realized that the api for syncing audio was bugged, so there's a hack for it in this repository.

[Calinou]

Closing, as WebM support has been removed from core in master. It's pending a reimplementation in an officially-supported GDExtension.

Once this extension is ready, I recommend opening an issue on its issue tracker about supporting transparency channel in WebM videos.