Patent ID: 7103839
Filing Date: 2006-09-05
Classification: G11B

Abstract:
1. A computer program product, tangibly stored on a computer-readable medium, for calculating the validity of a cached frame of a movie in a movie compositing system, comprising instructions operable to cause a programmable processor to: maintain a global editing timestamp that is updated with each editing operation performed by the system, the global editing timestamp representing an edit sequence position in a sequence of edits made to the movie; establish an interval list for each node in a compositing tree defining a movie, each node having a timeline that maps to a master timeline of the movie, an interval list for a node including, for each interval in the node's timeline, a single editing timestamp; update the interval list for a node when the node is edited; and use the interval list for a first node to evaluate the validity of a cached frame for a particular interval of the master timeline, the cached frame having been produced by compositing the first node in the compositing tree, the evaluation being performed by (a) comparing (i) an editing timestamp associated with the cached frame with (ii) the editing timestamps of intervals in the interval list that map to at least a portion of the interval of the master timeline, and (b) treating the cached frame as invalid if any of the intervals' editing timestamps is later than the editing timestamp associated with the cached frame.