Paints since the source loaded, monotonic within it and reset on source swap.
It counts paints, not source frames: two paints of one media position can
take two sequence numbers. Source-frame identity is carried separately by
the presented frame's frameId and media timestamp.
Paints since the source loaded, monotonic within it and reset on source swap. It counts paints, not source frames: two paints of one media position can take two sequence numbers. Source-frame identity is carried separately by the presented frame's frameId and media timestamp.