Audio for Videos

[EricBAndrews]

Checklist

• I have read CONTRIBUTING.md
• I have described what this PR contains
• If this PR alters the UI, I have attached pictures/videos
• This PR addresses one or more open issues that were assigned to me:
  - closes Audio for Videos #1489

Pull Request Information

Enhances video handling:

• mp4s can now play audio
• Videos with audio now show a mute button on the top right
• Default mute behavior can be controlled in settings (General -> Mute Videos)
• Tapping videos now pauses them instead of stops them
• mp4s now loop

Known Issues

• Interactive dismissal causes the video to start over and stop almost immediately. If audio is on, this causes a short clip of audio to play. This is due to an issue with our sheet dismissal: Interactive sheet dismissal triggers second render #1492

[Sjmarf]

Nice work!

Pressing the volume up button whilst playing a muted video unmutes the AVQueuePlayer, but the mute button in the UI doesn't get updated. Maybe we need to watch player.muted for changes and update muted if so? Could be tricky though if a view update doesn't get triggered when player.muted changes.

[EricBAndrews]

Ooh, nice catch! I've added some observation code that should sort it out.

[Sjmarf]

LGTM! It would be nice if videos were paused once they leave the screen. If I unmute a video and scroll away, the audio keeps playing.