The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 14, 1998
Filed:
Dec. 23, 1996
Shanwei Cen, Aloha, OR (US);
Tektronix, Inc., Wilsonville, OR (US);
Abstract
Reverse playback of MPEG video from a random access source takes advantage of the symmetry of B frames within an IB data stream. The IB data stream is processed by a parsing algorithm to identify within the B frames during playback those bits associated with motion vector identification and values to develop a parsed B frame table. When the IB data stream is output from the storage source for reverse playback, the IB data stream is rearranged into a reversed IB data stream. As each B frame is processed prior to input to an MPEG decoder, the parsed B frame table is used to manipulate the appropriate bits within the B frames to turn forward motion vectors into backward motion vectors, and vice versa. Then when the B frame is decoded by the MPEG decoder the respective motion vectors are associated with the appropriate I frames within the reversed IB data stream to produce accurate decoding of the B frames during reverse playback. Alternatively the MPEG decoder controller may be modified to provide both forward and reverse playback capabilities by reversing the stores within a prediction module of the MPEG decoder so that for reverse playback the first I frame in the reversed IB data stream is input to a future store rather than a prior store and the next I frame is input to the prior store rather than the future store. Again the B frame motion vectors in this manner are associated with the proper I frames for decoding.