Abstract: In some embodiments, a method receives a first ranking of content delivery networks for a playback session of a video and receives global constraints for the content delivery networks. The global constraints define an allocation for respective content delivery networks. The method alters a score for a content delivery network in the first ranking to generate a second ranking of content delivery networks. Then, a content delivery network is selected from the second ranking for the playback session of the video.

Abstract: In some embodiments, a method receives a plurality of video segments of a video using a plurality of computing instances and measures data received for the plurality of computing instances during a time window. A video segment for a computing instance in the plurality of computing instances is not fully downloaded during the time window. The method calculates a video delivery metric for the plurality of computing instances based on the data received and calculates an evaluation measurement based on the video delivery metric. The evaluation measurement is used to control an addition or a termination of a computing instance.

Abstract: In some embodiments, a method sends a set of requests for a video using a first protocol. The first protocol is selected from a plurality of protocols available for use in a playback session for the video. The method compares a first performance of the first protocol and a second performance of a second protocol and determines whether to switch from using the first protocol to the second protocol in the playback session based on the comparing.

Abstract: In some embodiments, a method receives session features for a session associated with a request for a video from a client and predicts network conditions for the session using the session features. A subset of available profiles is selected based on the network conditions. The available profiles are associated with a different playback characteristic. The method provides a profile ladder that includes the subset of available profiles for the playback of the video to the client. The profile ladder restricts the client to using the subset of available profiles to request segments of the video during the session.