Expand `ScreenSharePresets` to include 60 fps options

[nick-funk]

Describe the problem

Live kit does not support any high frame rate streams that are greater than 30 fps.

Element (Matrix client) uses the livekit-client sdk and is unable to provide 60 fps streams for screen sharing.

Users of this client are attempting to use Element for gaming and music live streaming:
element-hq/element-web#19008 (comment)

Gaming and music sometimes prefer a higher video bit rate over high resolution streams.

Describe the proposed solution

I would like to propose a h720pfps60 option for the ScreenSharePresets object to allow users to choose whether they want 1080p@30fps or 720p@60fps.

Example preset would look like so:

export const ScreenSharePresets = {
    ...
    h720fps60: new VideoPreset(1280, 720, 5_000_000, 60, 'medium'),
    ...
}

This would consume the same max bitrate as 1080p@30fps, but provide an option for higher frame rate video. This is very similar to what Discord does.

It would appear that NVENC, Intel QuickSync, and AMD's VCE all support 720p@60fps, so this hopefully has enough hardware encode/decode support to be feasible within livekit's underlying libraries.

Alternatives considered

Other than continue to use 30 fps video for these use-cases, I am unsure what else can be considered.

Importance

would make my life easier

Additional Information

Thank you for your consideration in this matter, y'all make a great SDK. I've seen it used in a lot of places.

I hope you're able to consider my (hopefully) modest proposal.

Have good one!