The latest Chromium supports APNG finally.
It will be included in the Chrome 59 release.
Microsoft, it's time to move!
Chromium developers are planning to add APNG support: https://bugs.chromium.org/p/chromium/issues/detail?id=1171 (see the latest activity in the issue).
The OGG container format is currently under consideration https://dev.modern.ie/platform/status/oggcontainer
Ogg Vorbis and Opus files are mandatory formats.
Opus is now in preview builds behind a flag. Please see https://blogs.windows.com/msedgedev/2016/04/18/webm-vp9-and-opus-support-in-microsoft-edge/
You are liars!
Edge 14 can't play even default example opus files:
https://opus-codec.org/examples/ (see Example of use in a web page).
Good news, thanks! Please don't forget about the Ogg Vorbis support. This format is very popular on the Wikipedia, for example.
WOW! I can't believe it! Great news!
Brotli landed in Windows Insider Preview build 14986. You can follow progress at https://developer.microsoft.com/en-us/microsoft-edge/platform/status/brotlicompresseddataformat/
CSS Box Alignment is now on the Microsoft Edge backlog. You can track the status at https://dev.modern.ie/platform/status/boxalignment/
WebM is in development – http://dev.modern.ie/platform/status/webmcontainer/