Application enhancement tracks

摘要

Systems and methods of providing enhanced digital media playback through application enhancement tracks are described. Application enhancement tracks are derived from the main content that they are associated with and are encoded to aid the performance of one or more functions related to the content, such as visual-search using a video application enhancement track, or trick-play track. In several embodiments, a method of decoding a media file for play back includes obtaining a media file containing compressed content and an accompanying application enhancement track which is a subset of the compressed content, playing back the compressed content, and decoding frames of the application enhancement track at a rate proportional to a visual-search speed and from a location determined by the portion of the compressed content most recently played back.

主权项

1. A method of encoding and playing back a media file, comprising:
extracting a video track from an original media file, where content is encoded in the video track; using the encoded content to encode a tricky-play track configured to enable the visual-search of the video track, where encoding the tricky-play track includes encoding at least one key frame that corresponds to a frame in the encoded content that is not a key frame and where the distance between key frames in the encoded content is not uniform; requesting portions of the encoded content from a media server using HTTP using a playback device; playing back a portion of the compressed video track using the playback device; receiving a trick-play request using the playback device; determining, in response to the received trick-play request, a position in the trick-play track corresponding to the position of the compressed video track being played using a first index using the playback device; playing back a portion of the trick-play track starting from the determined position in the trick-play track using the playback device; receiving a normal-play request using the playback device; determining, in response to the received normal-play request, a position in the compressed video track corresponding to the position of the trick-play track being played using a second index using the playback device; locating a key frame with the closest timestamp preceding the determined position in the compressed video track; recursively decoding the located key frame and decoding the difference frames between the located key frame and the difference frame at the determined position in the compressed video track; and playing back a portion of the compressed video track starting from the difference frame at the determined position in the compressed video track.