Concept for picture/video data streams allowing efficient reducibility or efficient random access
A video data stream is rendered reducible in a manner so that the reduction leads to a restriction of pictures of the reduced video data stream to merely a predetermined subarea of the pictures of the original video data stream and in a manner so that transcoding, such as re-quantization, may be avoided and a conformance of the reduced video data stream relative to the codec underlying the original video data stream be maintained. This is achieved by providing the video data stream with information including an indication of the predetermined subarea and replacement indices for redirecting the indices included by the payload portion so as to refer to, and/or replacement parameters for adjusting the first set of coding parameter settings so as to result in, a second set of coding parameter settings.
1. A method for decoding a data stream having a picture encoded thereinto, the method comprising
reconstructing the picture from the data stream, and
synthesizing a target picture on the basis of the picture by
reading, as part of displacing information contained in the data stream, from the data stream, for each predetermined subregion of a set of predetermined subregions of the picture,
first position information on a position of the respective predetermined subregion in the target picture area,
second information on a position of the respective predetermined subregion within the picture, and
information on a rotation when mapping the respective predetermined subregion between the target picture area and the picture,
displacing and rotating each of the predetermined subregions of the set of predetermined subregions of the picture relative to an overlay of the picture onto the area of the target picture according to the first position information, the second position information and the information on the rotation,
wherein the method further comprises reading from the data stream default filling information which indicates how to fill a portion of the target picture where none of the set of predetermined subregions of the picture lies according to the displacing information.
2. The method according to claim 1 , wherein the picture is coded into the data stream in units of tiles, into which the picture is sub-divided, without spatial coding inter-dependencies across boundaries of the tiles and by use of a coding order which traverses each tile before a next tile in a raster scan tile order.