Abstract
Dynamic adaptive streaming via HTTP (DASH) has been popular disseminated over the Internet especially under the circumstances of the time varying network, which it is currently the most challenging for providing smoothly video streaming via high quality. In DASH system, after completing the download of one segment, the player estimates the available network bandwidth by calculating the downloading throughput and then adapting the video bitrate level based on its estimations. However, the estimated bandwidth in the application layer is not accurate due to off-intervals appearance during the downloading process. To avoid the unfairness of bandwidth estimation by the clients, this work proposes a logarithmic approach for received network bandwidth, which includes increasing or decreasing this bandwidth logarithmically to converge the fair share bandwidth (estimated bandwidth). After obtaining the measured bandwidth, an adaptive bitrate algorithm is proposed by considering this measured bandwidth in addition to video buffer occupancy. The video buffer model is associated with three thresholds (i.e. one for initial startup and two for operating thresholds). When the video buffer’s level stays between the two operating thresholds, the video bitrate will keep unchanged. Otherwise, when the buffer occupancy is too high or too low, an appropriate video bitrate is chosen to avoid buffer overflow/underflow. Simulation results show that the proposed scheme is able to converge the measured bandwidth to the fair share bandwidth very quickly. Also the proposed scheme is compared with conventional scheme, we found that our proposed scheme outperforms in achieving the best performance in terms of efficiency, stability and fairness.
Highlights
In last few years, HTTP adaptive video streaming has been widely used in Internet video technologies such as Microsoft Smooth Streaming, Netflix, Apples HLS, Adobes HDS and Akamai HD [1], [2], since the use of HTTP over TCP is easy to configure and simplify the traversal of firewalls
In Dynamic Adaptive Streaming over HTTP (DASH) systems, each video is encoded into multiple representations of different bitrates and each representation is divided into multiple segments (2-10 seconds of video time)
A bitrate adaptive approach is designed on the basis of stability and fairness of DASH system under the scenario that many clients compete for network resources
Summary
HTTP adaptive video streaming has been widely used in Internet video technologies such as Microsoft Smooth Streaming, Netflix, Apples HLS, Adobes HDS and Akamai HD [1], [2], since the use of HTTP over TCP is easy to configure and simplify the traversal of firewalls. Under time-varying bandwidth condition, requesting a low video bitrate will produce more opportunities for rate selection, and well ensure high stability (smoothness) with continuous video playback but it causes a low video quality with low bandwidth usage (inefficiency) Another tradeoff challenging is between sensitivity and stability, since the channel bandwidth is inherently different in time, the high sensitivity of the bitrate control technique usually makes the video bitrate identical with the bandwidth and leading to high instability. On other side for stable and smooth video bitrate, we propose an adaptive bitrate algorithm that takes the measured bandwidth based on increment scheme and the buffer occupancy level into account for keeping a continuous video playback and selecting the best video bitrate to download the segment. Our approaches outperform the existing algorithms in measuring the fair share bandwidth, achieving fairness, buffer stability and reducing the number of video bitrates switching
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