What is the clock reference for the captureTime for webrtc remote sources?

[murillo128]

Currently the spec says:

For video frames coming from remote source, the capture time is based 
on the RTP timestamp of the frame and estimated using clock synchronization. 

However, it is not clear (at least for me) which clock is used for reference, the sender or the received one, and what does clock synchronization actually means.

[drkron]

The (perhaps implicit) assumption is that all timestamps have the same reference, so the capture timestamp is specified in reference to the receiver's clock, which is where the timestamps are exposed.

[murillo128]

doesn't seem a bad assumption (expecially if we include the catpureTimestamp as proposed here #86), but would be great if we could make it explicit