Rendering: Timing and Mediacapture-transform

[aboba]

The following demos utilize mediacapture-transform on input (transforming a MediaStreamTrack to VideoFrames) and output (going from VideoFrames to a MediaStreamTrack):

1. No network version: https://webrtc.internaut.com/wc/wcWorker/
2. With network (bounced off an echo server): https://webrtc.internaut.com/wc/wtSender10/

While demo #2 includes a reordering buffer, neither demo implements a jitter buffer. If you place a metronome or fan in the background, some jitter can be observed, though it is usually not extreme.

What smoothing functionality does the mediacapture-transform API provide in VideoTrackGenerator? No behavior is mandated in the specification. Is there an assumption that a jitter buffer is present upstream, or does the API provide some smoothing and/or synchronization functionality?

Related: w3c/mediacapture-transform#86