Methods for reduced cost insertion of video subwindows into compressed video

Methods and apparatus for encoding image data to facilitate subsequent insertion of local image data. Also methods and apparatus for inserting image data, e.g., at local broadcast stations, without having to fully decode a received encoded bitstream. The encoding methods involve treating images to be encoded as a plurality of distinct, non-overlapping image regions or segments for encoding purposes. Image segments which are designated for use for local data insertion are not used as reference data for motion compensated prediction purposes when generating motion vectors to represent image areas, e.g., the area representing the main picture, which are outside the local data insertion segments. Because image segments which may be replaced are not used as reference data for image segments which will not be replaced, unintentional prediction errors which might otherwise result from replacing one or more image segments as part of a local data insertion operation are avoided.