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 non-transitory digital storage medium having a computer program stored thereon to perform, when said computer program is run by a computer, a method for decoding a data stream having a picture encoded thereinto, the method comprising
reconstructing the picture from the data stream, and
reading, for syntheses of a target picture on the basis of the picture, from the data stream displacing information which indicates how to displace each of a set of predetermined subregions of the picture within an area of the target picture, wherein the reading comprises reading, as part of the displacing information, from the data stream
a count of the predetermined subregions within the set of predetermined subregions of the picture,
size parameters defining a size of the target picture,
for each predetermined subregion of the set of predetermined subregions of the picture,
a width, a height, a top sample row and a left-most sample column of the respective predetermined subregion in the target picture and
a further width, a further height, a further top sample row and a further left-most sample column of the respective predetermined subregion within the picture; and
displacing each of the predetermined subregions of the set of predetermined subregions of the picture within the target picture according to the width, the height, the top sample row and the left-most sample column of the respective predetermined subregion of the picture within the target picture and the further width, the further height, the further top sample row and the further left-most sample column of the respective predetermined subregion of the picture within the picture, as read for the respective predetermined subregion,
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 is displaced to according to the displacing information.
2. The non-transitory digital storage medium according to claim 1 , wherein the set of subregion of the picture is a subset of a gapless and overlap-free spatial partitioning of the picture into an array of subregions.
3. The non-transitory digital storage medium according to claim 1 , wherein the displacing information comprises
for each predetermined subregion of the set of predetermined subregion of the picture,
information on a rotation and information on a mirroring when mapping the respective predetermined subregion between the target picture and the picture.
4. The non-transitory digital storage medium according to claim 3 , wherein the data stream has a sequence of pictures encoded thereinto, wherein the displacing information is valid for the sequence of pictures.
5. The non-transitory digital storage medium according to claim 4 , wherein the target picture area represents a cubic projection of a panoramic scene.
6. The non-transitory digital storage medium according to claim 1 , wherein the displacing information indicates how to displace each of a set of predetermined subregions of the picture within an area of the target picture in a manner that allows for
a change of a spatial relative arrangement of the predetermined subregions within the picture relative to a spatial relative arrangement of the predetermined subregions within the target picture, and
a scaling of each predetermined subregion between the picture and the target picture.
7. The non-transitory digital storage medium according to claim 1 , wherein the displacing information comprises
for each predetermined subregion of the set of predetermined subregions of the picture, one syntax element for each of
the width of the respective predetermined subregion of the picture within the target picture,
the height of the respective predetermined subregion of the picture within the target picture,
the top sample row of the respective predetermined subregion of the picture within the target picture,
the left-most sample column of the respective predetermined subregion of the picture within the target picture,
the further width of the respective predetermined subregion of the picture within the picture,
the further height of the respective predetermined subregion of the picture within the picture,
the further top sample row of the respective predetermined subregion of the picture within the picture, and
the further left-most sample column of the respective predetermined subregion of the picture within the picture.
8. The non-transitory digital storage medium according to claim 7 , wherein the displacing information comprises
for each predetermined subregion of the set of predetermined subregion of the picture,
information on a rotation and information on a mirroring when mapping the respective predetermined subregion between the target picture and the picture.
9. The non-transitory digital storage medium according to claim 8 , wherein the data stream has a sequence of pictures encoded thereinto, wherein the displacing information is valid for the sequence of pictures.
10. The non-transitory digital storage medium according to claim 9 , wherein the target picture represents a cubic projection of a panoramic scene.