Despite the growing popularity of video streaming over the Internet, problems such as re-buffering and high startup latency continue to plague users. In this paper, we present an end-to-end characterization of Yahoo's video streaming service, analyzing over 500 million video chunks downloaded over a two-week period. We gain unique visibility into the causes of performance degradation by instrumenting both the CDN server and the client player at the chunk level, while also collecting frequent snapshots of TCP variables from the server network stack. We uncover a range of performance issues, including an asynchronous disk-read timer and cache misses at the server, high latency and latency variability in the network, and buffering delays and dropped frames at the client. Looking across chunks in the same session, or destined to the same IP prefix, we see how some performance problems are relatively persistent, depending on the video's popularity, the distance between the client and server, and the client's operating system, browser, and Flash runtime.
There is a rich area of related work in characterizing video-streaming quality. @cite_28 uses ISP packet traces to characterize video while @cite_6 uses CDN-side data to study content and Live vs VoD access patterns. Client-side data and a clustering approach is used in @cite_26 to find critical problems related to user's ISP, CDN, or content provider. @cite_19 characterizes popularity in user-generated content video system. Our work differs from previous work by collecting and joining fine-grained per-chunk measurements from both sides and direct instrumentation of the video delivery path, including the client's download stack and rendering path.
@cite_28 @cite_19 @cite_26 @cite_6
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The key role that video quality plays in impacting user engagement, and consequently providers' revenues, has motivated recent efforts in improving the quality of Internet video. This includes work on adaptive bitrate selection, multi-CDN optimization, and global control plane architectures. Before we embark on deploying these designs, we need to first understand the nature of video of quality problems to see if this complexity is necessary, and if simpler approaches can yield comparable benefits. To this end, this paper is a first attempt to shed some light on the structure of video quality problems. Using measurements from 300 million video sessions over a two-week period, we identify recurrent problems using a hierarchical clustering approach over the space of client session attributes (e.g., CDN, AS, connectivity). Our key findings are that: (1) a small number (2 ) of critical clusters account for 83 of join failure problems (44--84 for other metrics); (2) many problem events (50 ) persist for at least 2 hours; (3) a majority of these problems (e.g., 60 of join failures, 30--60 for other metrics) are related to content provider, CDN, or client ISP issues. Building on these insights, we evaluate the potential improvement by focusing on addressing these recurrent problems and find that fixing just 1 of these clusters can reduce the number of problematic sessions by 55 for join failures (15 --40 for other metrics). This paper investigates HTTP streaming traffic from an ISP perspective. As streaming traffic now represents nearly half of the residential Internet traffic, understanding its characteristics is important. We focus on two major video sharing sites, YouTube and DailyMotion. We use ten packet traces from a residential ISP network, five for ADSL and five for FTTH customers, captured between 2008 and 2011. Covering a time span of four years allows us to identify changes in the service infrastructure of some providers. From the packet traces, we infer for each streaming flow the video characteristics, such as duration and encoding rate, as well as TCP flow characteristics. Using additional information from the BGP routing tables allows us to identify the originating Autonomous System (AS). With this data, we can uncover: the server side distribution policy, the impact of the serving AS on the flow characteristics and the impact of the reception quality on user behavior. A unique aspect of our work is how to measure the reception quality of the video and its impact on the viewing behavior. We see that not even half of the videos are fully downloaded. For short videos of 3 minutes or less, users stop downloading at any point, while for videos longer than 3 minutes, users either stop downloading early on or fully download the video. When the reception quality deteriorates, fewer videos are fully downloaded, and the decision to interrupt download is taken earlier. We conclude that (i) the video sharing sites have a major control over the delivery of the video and its reception quality through DNS resolution and server side streaming policy, and (ii) that only half of the videos are fully downloaded and that this fraction dramatically drops when the video reception quality is bad. The emergence of smart edge-network content item hotspots, which are equipped with huge storage space (e.g., several GBs), opens up the opportunity to study the possibility of delivering videos at the edge network. Different from both the conventional content item delivery network (CDN) and the peer-to-peer (P2P) scheme, this new delivery paradigm, namely edge video CDN, requires up to millions of edge hotspots located at users’ homes offices to be coordinately managed to serve mobile video content item. Specifically, two challenges are involved in building edge video CDN, including how edge content item hotspots should be organized to serve users, and how content items should be replicated to them at different locations to serve users. To address these challenges, we propose our data-driven design as follows. First, we formulate an edge region partition problem to jointly maximize the quality experienced by users and minimize the replication cost, which is NP-hard in nature, and we design a Voronoi-like partition algorithm to generate optimal service cells. Second, to replicate content items to edge-network content item hotspots, we propose an edge request prediction based replication strategy, which carries out the replication in a server peak offloading manner. We implement our design and use trace-driven experiments to verify its effectiveness. Compared with conventional centralized CDN and popularity-based replication, our design can significantly improve users’ quality of experience, in terms of users’ perceived bandwidth and latency, up to 40 . The distribution of videos over the Internet is drastically transforming how media is consumed and monetized. Content providers, such as media outlets and video subscription services, would like to ensure that their videos do not fail, startup quickly, and play without interruptions. In return for their investment in video stream quality, content providers expect less viewer abandonment, more viewer engagement, and a greater fraction of repeat viewers, resulting in greater revenues. The key question for a content provider or a CDN is whether and to what extent changes in video quality can cause changes in viewer behavior. Our work is the first to establish a causal relationship between video quality and viewer behavior, taking a step beyond purely correlational studies. To establish causality, we use Quasi-Experimental Designs, a novel technique adapted from the medical and social sciences. We study the impact of video stream quality on viewer behavior in a scientific data-driven manner by using extensive traces from Akamai's streaming network that include 23 million views from 6.7 million unique viewers. We show that viewers start to abandon a video if it takes more than 2 seconds to start up, with each incremental delay of 1 second resulting in a 5.8 increase in the abandonment rate. Further, we show that a moderate amount of interruptions can decrease the average play time of a viewer by a significant amount. A viewer who experiences a rebuffer delay equal to 1 of the video duration plays 5 less of the video in comparison to a similar viewer who experienced no rebuffering. Finally, we show that a viewer who experienced failure is 2.32 less likely to revisit the same site within a week than a similar viewer who did not experience a failure.