Anpassning av bithastighet för mobil video

The last few years mobile devices have become more and more powerful and with larger and more colorful displays. This has paved the way for delivering high video quality forthese devices. Every year each of the big mobile manufacturers, Samsung, Sony, HTC and so on, release numerous devices - each with different technical specifications. Some of them follows most of the standards, most of them follows some of the standards. This never ending flow of new devices with varying amount of standards followed combines to fragmenting the market in a way that makes it extremely difficult to support different devices when developing mobile clients or mobile web sites. This fragmentation also makes it diffcult to deliver the best possible video quality to each individual device. This thesis proposes a way of combined approaches to find out the available bandwidth for a specific device, and thus be able to adapt the video bit-rate. The different techniques which winded up in the final solutions consists of values found in HTTP headers as well as values parsed from a User-Agent Profile of a device, but also of more protocol specific solutions: iPhone Live Streaming, MBR ASF and a modification to Darwin Streaming Server. As a final fallback a small sample image was downloaded before the video was requested to provide an approximate measurement of the available bandwidth. The solution proposed in this thesis covers three delivery methods used; MMS, RTSP and progressive download. A switch in bit-rate will not happen in all cases, however, the solution will improve the user experience for many users.Validerat; 20121126 (global_studentproject_submitter