Encoding/decoding moving images with forward and backward keyframes for forward and reverse display
Patent 5267334 Issued on November 30, 1993. Estimated Expiration Date: 
January 21, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
January 21, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesApparatus for adaptive inter-frame predictive encoding of video signal Inter-frame predictive encoding system with encoded and transmitted prediction error Three dimensional motion compensated video coding Patent #: 4999705 InventorsAssigneeApplicationNo. 006686 filed on 01/21/1993US Classes:382/236, Interframe coding (e.g., difference or motion detection)375/240.12, Predictive382/239Adaptive coding (i.e., changes based upon history, activity, busyness, etc.)ExaminersPrimary: Boudreau, Leo H.Assistant: Johns, Andrew W. Attorney, Agent or FirmInternational ClassesG06K 009/36H04N 007/12 AbstractA method of removing frame redundancy in a computer system for a sequence of moving images. The method comprises detecting a first scene change in the sequence of moving images and generating a first keyframe containing complete scene information for a first image. The first keyframe is known, in a preferred embodiment, as a "forward-facing" keyframe or intra frame, and it is normally present in CCITT compressed video data. The process then comprises generating at least one intermediate compressed frame, the at least one intermediate compressed frame containing difference information from the first image for at least one image following the first image in time in the sequence of moving images. In a preferred embodiment, this at least one frame is known as an inter frame. Finally, detecting a second scene change in the sequence of moving images and generating a second keyframe containing complete scene information for an image displayed at the time just prior to the second scene change. This is known, in the preferred embodiment, as a "backward-facing" keyframe. The first keyframe and the at least one intermediate compressed frame are linked for forward play, and the second keyframe and the intermediate compressed frames are linked in reverse for reverse play. In a preferred embodiment, the intra frame is used for generation of complete scene information when the images are played in the forward direction. When this sequence is played in reverse, the backward-facing keyframe is used for the generation of complete scene information.Other References
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