Multiplexing/demultiplexing method for superimposing sub- images on a main image.

摘要

A main image and at least one sub-image for superimposing on the main image are encoded in the following manner. The main image is subdivided into a plurality of main image regions that are compressed and encoded, including location information indicative of a location of each main image region in the main image. The sub-image is subdivided into a plurality of sub-image regions that are compressed and encoded, including location information indicative of a location where each of the sub-image regions is to be superimposed on the main image. Encoded data of the main image and sub-image regions are then arranged in such a manner that a main image region and a sub-image region which share the same location information are concatenated such that the encoded data of the sub-image region precedes that of the main image region. The encoded video sequence thus obtained are decoded in the following manner. A current region is decoded to obtain decoded data. Next, either one of the following steps (1) or (2) is performed if the location information of the current region is the same as that of the previous region: (1) discarding the decoded data of the current region when displaying the sub-image; and (2) displacing the decoded data of the previous region with that of the current region when not displaying the sub-image.