|Author:||Zhao, Hong Wei|
|Title:||The PID based algorithm for dynamic adaptive streaming over HTTP|
|Subject:||Streaming technology (Telecommunications)|
Multimedia communications -- Quality control.
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Computing|
|Pages:||vi, 65 pages : color illustrations|
|Abstract:||Today, the Dynamic Adaptive Streaming over HTTP (DASH) has become the major standard for online streaming media, some main online streaming providers (i.e. YouTube, Hulu, Netflix) have already implemented the DASH standard in their website. The basic DASH system divides the whole video into several chunks, each of these chunks has been encoded into different quality levels and they have the same length, then the DASH system will adaptively choose video chunk quality according to current estimating bandwidth. However, as the bandwidth is highly fluctuated in the real network, the basic DASH system is hard to maintain a stable video buffer size, even there will be buffer size freezing if the bandwidth drops suddenly. Besides, the frequent video quality switching will also significantly damage the user experience. To realize a better quality of experience (QOE), there should be a good tradeoff between video quality and buffer size. In order to realize this target, we design a well tuned PID based DASH algorithm. In this dissertation, we firstly propose an improved QOE metrics which is much more close to real human visual audit system, for quantizing the performance of algorithms and doing horizontal comparison with other algorithms. Then, we come up with a new PID based control logic without using linearization technique which might generate huge error in the system operation. As the bandwidth is highly fluctuated in the real network, so we could not fully depend on the PID controller which has significant delay while in the frequently changing situation. Therefore, we design the other video quality switching logic to make up this drawback in the PID logic, besides, this logic could avoid the frequent video quality switching. Finally, in order to find the best parameters of PID controller which is the hardest part in the controller design process, we introduce the Coordinate Descent Algorithm to automatically tune parameters, which leads to the obvious improvement in the algorithm performance.|
|Rights:||All rights reserved|
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