Patent ID: 8909922

Claim:
A playback device, comprising: a processor; memory containing a client application; wherein the client application configures the processor to: obtain a top level index file identifying a plurality of separate container files each containing one of a plurality of alternative streams of protected video, wherein each of the alternative streams of protected video includes video frames that are encrypted using a common set of frame keys comprising a plurality of different frame keys, wherein each of the container files containing the alternative streams of protected video comprises (i) an encrypted copy of the common set of frame keys and (ii) a set of DRM information that identifies encrypted portions of the video frames and frame keys to utilize in accessing the encrypted portions of the video frames, and wherein the set of DRM information in each of the plurality of alternative streams of protected video references the same common set of frame keys; obtain an encrypted copy of the common set of frame keys from a given container file and decrypt the encrypted copy of the common set of frame keys using a content key; obtain a set of DRM information from the given container file; obtain portions of protected video from the given container file containing one of the plurality of alternative streams of protected video; decrypt encrypted video frames from the obtained portions of video using the decrypted copy of the common set of frame keys according to the obtained set of DRM information; and playback the obtained portions of video.