| 摘要 |
In a decoder/display system, a pre-processing stage (10) re-codes intra coded macroblock data in an image to produce an independent representation which observes byte alignment. Macroblock data is stored in structured form (26) so that it may readily be indexed for fast copying into foreign images. To avoid differential coding problems, two separate representations of each macroblock are generated for use as the first in a line of macroblocks or as part of a continuation of a line of macroblocks. The pre-processing stage may be used to combine separately encoded pictures and also to separate sprites (objects having a defined boundary) from their original scene. The content of the pictures may be changed at run-time by choosing combinations of macroblocks in a sequence of images to produce the desired effect. Pre-processed macroblocks are loaded into memory (26) as primitive sprites or whole encoded pictures to provide a database of MPEG (or similar) image data which may be interactively introduced and moved within an MPEG sequence. The provision of the database enables a system to generate a variety of interactive effects, including the introduction of sprites and other separately encoded data to the scene, the modification of motion vectors immediately prior to decoding that allow video animation within the scene, and the run-time scrolling of large image backgrounds. |
