Method and apparatus for video decoding of area of interest in a bitstream
A video decoding method for decoding an input bitstream in which each of pictures has been encoded with being split into a plurality of tiles, the method includes decoding partial decoding information included in the input bitstream and determining one or more target tiles to be decoded among the plurality of tiles according to the partial decoding information; and decoding video data corresponding to the one or more target tiles, wherein the partial decoding information includes at least one of first information indicating whether to perform partial decoding and second information indicating an area on which partial decoding is to be performed.
1. A method of processing, by a processor, a first bitstream in which each of pictures has been encoded with being split into a plurality of tiles, each tile comprised of one or more coding tree units, the first bitstream including encoded pixel data of the pictures and parameters used for encoding the pictures, the method comprising:
receiving the first bitstream which includes tile split information and area information,
wherein the area information is included in a header of the first bitstream, the header being a Sequence Parameter Set containing parameters which are referenced in common by all of the pictures, and
wherein the area information comprises first and second syntax elements for respectively indicating horizontal and vertical coordinates of a reference position in the pictures, and third and fourth syntax elements for respectively indicating a width and a height from the reference position, and allows an area which includes two or more tiles;
generating a second bitstream to be decoded, by:
extracting, from the encoded pixel data of the pictures included in the first bitstream, only encoded pixel data of an area extending by the width and the height indicated by the third and fourth syntax elements from the reference position indicated by the first and second syntax elements, and
modifying at least part of the parameters in the first bitstream using the reference position, and the width and the height from the reference position which are defined by the area information; and
outputting the second bitstream to thereby decode the extracted encoded pixel data.
2. The method of claim 1 , wherein the area information included in the first bitstream is a null or default value set in a predetermined field of the first bitstream received from a video encoding apparatus; and
wherein at least part of the parameters in the first bitstream are modified by resetting the null or default value set in the predetermined field of the first bitstream.
3. The method of claim 1 , wherein the generating of the second bitstream comprises:
decoding a flag indicating whether to perform partial decoding from the header of the first bitstream; and
when the flag indicates partial decoding, decoding the area information from the header of the first bitstream and generating the second bitstream which is comprised of only encoded pixel data corresponding to the area defined by the area information.
4. The method of claim 1 , wherein the area information further includes information for indicating an additional area expanded from the area,
wherein the additional area is defined as a proportion to a size of the area or an absolute size.
5. A non-transitory recording medium storing a second bitstream generated by a method of processing a first bitstream in which each of pictures has been encoded with being split into a plurality of tiles, each tile comprised of one or more coding tree units, the first bitstream including encoded pixel data of the pictures and parameters used for encoding the pictures, the method comprising:
receiving the first bitstream which includes tile split information and area information,
wherein the area information is included in a header of the first bitstream, the header being a Sequence Parameter Set containing parameters which are referenced in common by all of the pictures, and
wherein the area information comprises first and second syntax elements for respectively indicating horizontal and vertical coordinates of a reference position in the pictures, and third and fourth syntax elements for respectively indicating a width and a height from the reference position, and allows an area which includes two or more tiles;
generating a second bitstream to be decoded, by:
extracting, from the encoded pixel data of the pictures included in the first bitstream, only encoded pixel data of an area extending by the width and the height indicated by the third and fourth syntax elements from the reference position indicated by the first and second syntax elements, and
modifying at least part of the parameters in the first bitstream using the reference position, and the width and the height from the reference position which are defined by the area information; and
outputting the second bitstream to thereby decode the extracted encoded pixel data.