Adaptive bitrate streaming (ABR) has become thede factotechnique for videostreaming over the Internet. Despite a flurry of techniques, achieving high quality ABRstreaming over cellular networks remains a tremendous challenge. First, the design ofan ABR scheme needs to balance conflicting Quality of Experience (QoE) metrics suchas video quality, quality changes, stalls and startup performance, which is even harderunder highly dynamic bandwidth in cellular network. Second, streaming providers havebeen moving towards using Variable Bitrate (VBR) encodings for the video content,which introduces new challenges for ABR streaming, whose nature and implicationsare little understood. Third, mobile video streaming consumes a lot of data. Althoughmany video and network providers currently offer data saving options, the existingpractices are suboptimal in QoE and resource usage. Last, when the audio and videotracks are stored separately, video and audio rate adaptation needs to be dynamicallycoordinated to achieve good overall streaming experience, which presents interestingchallenges while, somewhat surprisingly, has received little attention by the researchcommunity. In this dissertation, we tackle each of the above four challenges.
翻译:适应性位速率流(ABR)已经成为互联网视频流的事实上的技术。 尽管技术繁多,但是在蜂窝网络上实现高质量的ABR流仍是一个巨大的挑战。 首先,设计一个ABR计划需要平衡相互冲突的经验质量(QoE)衡量标准,比如视频质量、质量变化、摊位和启动性能,这在蜂窝网络高度动态带宽下甚至更为困难。 其次,流体提供者已经转向对视频内容使用可变的Bitrate(VBR)编码,这给ABR流带来了新的挑战,其性质和含义都几乎不为人所知。第三,移动视频流耗用了大量数据。虽然许多视频和网络提供者目前提供数据保存选项,但现有的做法在QE和资源使用方面并不理想。最后,当音频和视频轨迹被分开存储时,视频和音频率适应需要动态协调,以获得良好的总体流学经验,这带来了有趣的挑战,而令人惊讶的是,而研究界却很少关注上述四个挑战。