Optimal Frame Selection with Adaptive Playout for Delivering Stored Video under Constrained Resources
ABSTRACT In this paper, we propose a server-client coordinated joint optimal frame selection with adaptive playout for delivering stored video under both limited channel bandwidth and finite client buffer condition. In particular, the client will reduce the frame playout rate whenever its buffer fullness level falls below a given threshold in an attempt to prevent buffer underflow. And when the buffer fullness exceeds the threshold, the client will switch back to the normal frame playout rate. The server is aware of the adaptive playout decision made by the client and incorporates the decision into its optimal frame selection framework for joint optimization. The objective is to minimize the number of frames that must be discarded in order to prevent client buffer underflow or overflow and make full use of the limited bandwidth resource.
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ABSTRACT: 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.IEEE Transactions on Multimedia 11/2011; 14(3). · 1.75 Impact Factor
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ABSTRACT: Wireless Multimedia service faces the difficulty of QoS decrease caused by the cache underflow, due to both the unreliable and time-varying nature of the wireless channel. In order to reduce the probability of the cache outage, a statistical model is established to estimate the underflow time of the cache. Based on the estimation of the underflow time, an adaptive playout algorithm with dual-threshold to adjust the frame rate is presented. This approach adjusts the threshold dynamically according to the channel conditions and the status of the cache, and thus regulates the frame rate timely. Moreover, the algorithm possesses scene-aware characteristics, since it adjusts the playout rate according to the motion intensity of the playout scenes to reduce the underflow probability of the cache and provide better QoS. Simulation results show that as compared to other adaptive media playout algorithms, the proposed algorithm efficiently reduces the probability of the cache underflow, especially in low rate channel and timevarying rate environment, and provides better visual quality.IEEE Transactions on Consumer Electronics 12/2010; · 1.09 Impact Factor
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ABSTRACT: Recently smooth adaptive media playout (SAMP) was suggested to deal with the visual quality degradation problem caused by the fluctuation of playout speed in conventional AMP. However, while encountering the burst packet losses, it still had a potential buffer outage risk if buffer level was not safe enough. In this paper, a safety guaranteed SAMP (SG SAMP) algorithm is proposed to deal with the above hazard. Whenever the current buffer level deviates from the predefined safe area, the linear playout adjustment order is triggered to maintain the buffer safety. The simulation results have shown that SG SAMP outperforms SAMP in reducing the buffer outage probability and provides smooth and reliable playback, especially in wireless video streaming. The playout adjustment number and the frame loss number are both about 30% less.01/2010;