[Remote Playback] Refinements to Remote Playback protocol

[markafoltz]

This issue tracks potential refinements to the remote playback messages contained in these TODOs:

Frequency to update current-time (HtmlMediaElement does every 250ms?)
extended mime types in source tag?
media queries replacing URLs?

[markafoltz]

I suggest closing this issue and opening new ones for items that deserve further discussion.

extended mime types in source tag?

This is already included in the current spec.

Frequency to update current-time (HtmlMediaElement does every 250ms?)

It's currently specified as 350ms. If we wish to change this, probably makes sense to spin off into a separate issue to discuss.

media queries replacing URLs?

I can't find any reference to this TODO in the document. I might have to go through commit history to get the context on this.