1. A playback device configured to perform multiphase adaptive bitrate streaming by requesting portions of encoded media from a plurality of alternative streams of encoded media that are encoded at different maximum bitrates in response to changes in streaming conditions, the playback device comprising: a processor configured, via a client application, to request portions of files from a remote server; wherein the client application further configures the processor to: commence streaming of the encoded media in a first operational phase utilizing a first set of stream switching conditions by requesting portions of the encoded media from one of the plurality of alternative streams encoded at a specified maximum bitrate; measure streaming conditions for receiving the requested portions of the encoded media from a current one of the plurality of alternate streams having a current maximum bitrate; determine when a first set of stream switching conditions is satisfied in a first operational phase by the measured streaming conditions; request portions of the encoded media from another one of the plurality of alternative streams encoded at a maximum bitrate that is different than the current maximum bitrate in response to the determination that the first set of stream switching conditions are satisfied; determine when at least one phase transition criterion of the first operational phase is satisfied by the measured streaming conditions; transition to a second operational phase utilizing a second set of stream switching conditions in response to the determination that the at least one transition criterion is satisfied; determine when the second set of stream switching conditions is satisfied in the second operational phase by the measured streaming conditions; and request portions of the encoded media from another one of the plurality of alternative streams encoded at a maximum bitrate that is different from the current maximum bitrate in response to the determination that the second set of stream switching conditions are satisfied.