  This paper aims to reduce the prebuffering requirements, while maintaining
continuity, for video streaming. Current approaches do this by making use of
adaptive media playout (AMP) to reduce the playout rate. However, this
introduces playout distortion to the viewers and increases the viewing latency.
We approach this by proposing a frame rate optimization framework that adjusts
both the encoder frame generation rate and the decoder playout frame rate.
Firstly, we model this problem as the joint adjustment of the encoder frame
generation interval and the decoder playout frame interval. This model is used
with a discontinuity penalty virtual buffer to track the accumulated difference
between the receiving frame interval and the playout frame interval. We then
apply Lyapunov optimization to the model to systematically derive a pair of
decoupled optimization policies. We show that the occupancy of the
discontinuity penalty virtual buffer is correlated to the video discontinuity
and that this framework produces a very low playout distortion in addition to a
significant reduction in the prebuffering requirements compared to existing
approaches. Secondly, we introduced a delay constraint into the framework by
using a delay accumulator virtual buffer. Simulation results show that the the
delay constrained framework provides a superior tradeoff between the video
quality and the delay introduced compared to the existing approach. Finally, we
analyzed the impact of delayed feedback between the receiver and the sender on
the optimization policies. We show that the delayed feedbacks have a minimal
impact on the optimization policies.
