Media: Issues with animated and transparent gifs uploaded to WordPress

[swissspidy]

Bug Description

As mentioned at #4599 (comment), there's a long-standing bug in WordPress core that causes thumbnails of animated gifs not to be animated. A second long-standing bug causes the thumbnails to lose their transparency.

Since we use image thumbnails for srcset, it causes animated gifs in stories to only be animated and transparent when the browser decides to use the full version.

Suggested Fix

Users will likely not realize it's a WordPress bug though. For that reason, I suggest not providing the image thumbnails in the REST API for animated gifs. This will make the editor use the original file at all times.

Downside: potentially larger file size served to users.

Alternative: fix WordPress core bug.

Expected Behaviour

Animated gifs uploaded to WordPress should stay animated in stories.

Steps to Reproduce

1. Upload animated gif to WordPress media library
2. Insert in story

Screenshots

Original, animated gif used:

Thumbnail used:

Additional Context

• Plugin Version: 1.0.0
• Operating System: macOS
• Browser: Chrome
• WordPress Version: 5.5

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Acceptance Criteria

Implementation Brief

[swissspidy]

Now that we have FFmpeg in the plugin, we could also just convert animated GIFS to MP4s... That would be superb!

#7232

[swissspidy]

Closing now that #7232 has landed 🎉