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: When media is streamed over best-effort networks, media data is buffered at the client to protect against playout interruptions due to packet losses and random delays. While the likelihood of an interruption decreases as more data is buffered, the latency that is introduced increases. In this paper we show how adaptive media playout (AMP), the variation of the playout speed of media frames depending on channel conditions, allows the client to buffer less data, thus introducing less delay, for a given buffer underflow probability. We proceed by defining models for the streaming media system and the random, lossy, packet delivery channel. Our streaming system model buffers media at the client, and combats packet losses with deadline-constrained automatic repeat request (ARQ). For the channel, we define a two-state Markov model that features state-dependent packet loss probability. Using the models, we develop a Markov chain analysis to examine the tradeoff between buffer underflow probability and latency for AMP-augmented video streaming. The results of the analysis, verified with simulation experiments, indicate that AMP can greatly improve the tradeoff, allowing reduced latencies for a given buffer underflow probability.IEEE Transactions on Circuits and Systems for Video Technology 07/2004; · 1.82 Impact Factor
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ABSTRACT: Multimedia applications including video data require the smoothing of video playout to prevent potential discontinuity. In this paper, we propose a dynamic video playout smoothing method, called the Video Smoother, which dynamically adopts various playout rates in an attempt to compensate for high delay variance of networks. Specifically, if the number of frames in the buffer exceeds a given threshold (TH), the Smoother employs a maximum playout rate. Otherwise, the Smoother uses proportionally reduced rates in an effort to eliminate playout pauses resulting from the emptiness of the playout buffer. To determine THs under various loads, we present an analytic model assuming the Interrupted Poisson Process (IPP) arrival. Based on the analytic results, we establish a paradigm of determining THs and playout rates for achieving different playout qualities under various loads of networks. Finally, to demonstrate the viability of the Video Smoother, we have implemented a prototyping system including a multimedia teleconferencing application and the Video Smoother performing as part of the transport layer. The prototyping results show that the Video Smoother achieves smooth playout incurring only unnoticeable delays.Multimedia Tools and Applications 01/1998; 6:47-60. · 1.01 Impact Factor
Conference Proceeding: Adaptive playout for low latency video streaming[show abstract] [hide abstract]
ABSTRACT: Network variations in video streaming require sufficient data to be prebuffered at the client prior to playout. This receiver buffer prevents the display process from starvation in case of network congestion. Prebuffering, however, is also responsible for the major part of the delay between requesting a media stream and playing it at the receiver. We show how adaptive media playout can be employed to reduce the delay introduced by the receiver buffer while preserving the same resilience against buffer underflow as in non-adaptive media playout. For adaptive media playout we adjust the playout speed of the media packets depending on the condition of the channel and the current client buffer fullness. We employ a two-state Markov channel model to analyze the buffer underflow-delay trade-off for our adaptive playout strategy and show that for typical parameters the average end-to-end delay can be reduced by 1 to 2 secondsImage Processing, 2001. Proceedings. 2001 International Conference on; 02/2001