Efficient HTTP-based Adaptive Streaming of Linear and Interactive Videos
Vengatanathan Krishnamoorthi · Linköping studies in science and technology. Dissertations · 2018
Online video streaming has gained tremendous popularity over recent years and currently constitutes the majority of Internet traffic.As large-scale ondemand streaming continues to gain popularity, several important questions and challenges remain unanswered.This thesis addresses open questions in the areas of efficient content delivery for HTTP-based Adaptive Streaming (HAS) from different perspectives (client, network and content provider) and in the design, implementation, and evaluation of interactive streaming applications over HAS.As streaming usage scales and new streaming services emerge, continuous improvements are required to both the infrastructure and the techniques used to deliver high-quality streams.In the context of Content Delivery Network (CDN) nodes or proxies, this thesis investigates the interaction between HAS clients and proxy caches.In particular, we propose and evaluate classes of content-aware and collaborative policies that take advantage of information that is already available, or share information among elements in the delivery chain, where all involved parties can benefit.Asides from the users' playback experience, it is also important for content providers to minimize users' startup times.We have designed and evaluated different classes of client-side policies that can prefetch data from the videos that the users are most likely to watch next, without negatively affecting the currently watched video.To help network providers to monitor and ensure that their customers enjoy good playback experiences, we have proposed and evaluated techniques that can be used to estimate clients' current buffer conditions.Since several services today stream over HTTPS, our solution is adapted to predict client buffer conditions by only observing encrypted network-level traffic.Our solution allows the operator to identify clients with low-buffer conditions and implement policies that help avoid playback stalls.The emergence of HAS as the de facto standard for delivering streaming content also opens the door to use it to deliver the next generation of streaming services, such as various forms of interactive services.This class of services is gaining popularity and is expected to be the next big thing in entertainment.For the area of interactive streaming, this thesis proposes, models, designs, and evaluates novel streaming applications such as interactive branched videos and multi-video stream bundles.For these applications, we design and evaluate careful prefetching policies that provides seamless playback (without stalls or switching delay) even when interactive branched video viewers defer their choices to the last possible moment and when users switches between alternative streams within multi-video stream bundles.Using optimization frameworks, we design and implement effective buffer management techniques for seamless playback experiences and evaluate several tradeoffs using our policies.The work was supported by the Swedish Graduate School in Computer Science (CUGS), the Center for Industrial Information Technology (CENIIT), and the Swedish Research Council (Vetenskapsrådet).Life as a PhD student is a fascinating journey of personal change and development.Yet, it is the people around you that have a large part in shaping this experience.Throughout my time as a PhD student, I have had the privilege of interacting with many that have made this journey possible and worthwhile.This thesis would not have been possible without the help, support and guidance from my primary adviser Dr. Niklas Carlsson.Niklas has been a forthcoming source of vision, insight, and guidance that I could count on at all times.Throughout my time here, you have played a big part in all of my successes and have taught valuable lessons, both in research and with life.Thank you for believing in me and for always motivating me towards the next goal.You will always be a role model who I look up to.I would also like to thank Prof. Nahid Shahmehri, my secondary adviser.Nahid has been instrumental in my development as a PhD student and has always kept a watchful eye over me.I thank you for giving me the opportunity, for showing genuine interest towards my education and my well-being, and for being an enthusiastic badminton partner.Among our collaborators, I would first like to mention Dr. Emir Halepovic for his valuable additions to our joint works.Thank you for being a patient listener, and for the industry insights that