Add proper AV1 and 7.1 audio support, please

[Max Overpower]

When playing files using the built-in media player on the LG C1, webOS 6, the support for AV1 and any kind of 7.1 audio is really lackluster:

In particular, when playing AV1 videos encoded using aomenc (the official AOM encoder) with the setting --enable-keyframe-filtering=2, there is a 10-15 second video freeze when starting playback and when seeking. The audio plays immediately from the moment where the video will eventually un-freeze and sync up. This encoder settings does universally mess with seeking, to some extent, particularly limiting seeking to each keyframe/GOP, but to mess up playback THAT much is not seen in any other mobile, desktop, or TV media player. This seriously needs fixing.

And another similarly atrocious flaw of the player, is that files with 7.1 audio do not play at all. I do not have a surround system, but it is expected that surround audio files are downmixed to your current audio setup, which does happen with 5.1 audio, but for whatever reason, if there is any 7.1 track in the file - it simply will not play. Which, again, is a behavior I have not seen on any other TV media player.
Lastly, PGS subtitle format is not supported by the media player, and such subtitles will not show up in the list. Which again just seems like laziness, though it's not as major of an issue.