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Third Party Issue
Votes
0
Found in
2021.3.37f1
2022.3.24f1
2023.2.18f1
6000.0.0b14
Issue ID
UUM-69641
Regression
No
WebGL Player does not display transparent backgrounds when using MOV files in a Render Texture
How to reproduce:
1. Open the “WebGLAlphaVideoPlayer“ project
2. Open the “SampleScene“
3. Build And Run
4. Observe the Player
Expected result: The background is transparent
Actual result: The background is a solid black color
Reproduced with: 2021.3.37f1, 2022.3.24f1, 2023.2.18f1, 6000.0.0b14
Reproduced on: macOS 14.3.1 (M1) (by reporter), macOS 13.6.4 (M1)
Not reproduced on: No other environment tested
Could not test with: Windows 11 (Multiple runtime errors are thrown)
Notes:
1. Expected and actual images are provided in the internal comments
2. Not reproducible in the Editor
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Resolution Note:
Unfortunately alpha video support in browsers (specifically with WebGL) is a bit of a minefield. The formats supported, and whether it works at all, is all over the place.
On MacOS, Chrome will support WebM and HEVC video with transparency. Safari supports HEVC (and the ProRes video from the bug repo) transparent video with the HTML Video tag, but the video loses its alpha channel as soon as you upload it to WebGL. I filed a WebKit bug for this, which you can track at https://bugs.webkit.org/show_bug.cgi?id=273006. That means Safari doesn't currently support transparent video at all with WebGL.
On Windows, Chrome WebGL will only support WebM with transparent video, but HEVC loses its alpha channel.
Unfortunately there's nothing we can do about this other than file the browser bug, since we are at the mercy of the browser decoding the video and uploading the results to WebGL.