KAUNAS UNIVERSITY OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE
FACULTY OF INFORMATICS
P175M108 CONTENT DISTRIBUTION SYSTEMS
ADAPTIVE STREAMING TECHNOLOGIES
Kalki Kumar Ballampalli
IFMU - 4
Lecturer: Assist. Vaidas Jukavičius
Date of submission: 2014-november-14
1. Adaptive Streaming Technologies
Adaptive streaming technologies share several critical aspects. First, they produce multiple files from the same source file to distribute to viewers watching on different powered devices via different connection speeds.
Second, they distribute the files adaptively, changing the stream that’s delivered to adapt to changes in effective throughput and available CPU cycles on the playback station.
Third, they all operate transparently to the user, so that the viewer clicks one button (rather than multiple buttons as with the movie trailer experience where users select the bitrate and video quality beforehand) and all stream switching occurs behind the scenes.
The viewer may notice a slight change in quality as the streams switch, but no action is required on his part. All technologies share similar operating characteristics as well, though there are some key differences.
For example, all adaptive streaming technologies monitor factors like video buffer status to assess effective throughput and CPU utilization and dropped frames to assess the available computing power on the playback station. This information is used to determine when to switch streams.
For example, if the video buffer is full and CPU utilization low, the adaptive streaming technology may switch to a higher quality stream to enhance the viewing experience. If the buffer drops below certain levels, or CPU utilization spikes above certain thresholds, the technology may switch to a lower quality stream.
The key implementation difference between the technologies is the involvement of a streaming server. Specifically, some technologies require a streaming server, and constant communication between the server and player.
Other technologies operate without a streaming server. The different quality streams are posted to different addresses on a web server or multiple web servers. The player monitors operating heuristics like CPU utilization and buffer status, decides when a stream switch is necessary and starts retrieving data from a different stream when appropriate.
Either way, adaptive streaming technologies enable producers to deliver outstanding quality streams at the high end of the bandwidth/power spectrum because they also serve the low end. Without adaptive streaming, most producers would either distribute a single mid-quality file that looks below average in the optimum viewing configuration, or create multiple files and force the viewer select the desired configuration. 2. Adaptive Streaming Vendors and Service Providers
The players fall into three general categories:
1. Technology Developers.
2. Service Providers.
3. Standard Based Technologies.
Prominent technology developers include:
Adobe with Flash-based Dynamic Streaming,
Apple with HTTP Live Streaming (HLS), and
Microsoft with Smooth Streaming for Silverlight.
Move Networks, which pioneered this market, has largely dropped out as a general-purpose technology provider. Several WebM-based HTML5 options are also under development or available, including technologies from Anevia and Quavlive.
Service providers include primarily Akamai, with its Akamai HD Network, which is a platform that can deliver to iOS devices, Flash and Silverlight clients. Several companies, most notably Netflix, have developed their own adaptive streaming technologies for internal use.
Standard-based technologies include Scalable Video Coding (SVC), which is an extension of the H.264 specification. In...
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