Method and apparatus for video decoding of area of interest in a bitstream
A method for decoding 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 method comprises receiving the first bitstream which includes tile split information and area information, generating a second bitstream to be decoded, by extracting, from the first bitstream, only encoded data corresponding to the area defined by the area information which is included in the header of the first bitstream, and modifying syntax elements in the first bitstream using the reference position, and the width and the height from the reference position included in the area information, and outputting the second bitstream to thereby decode the extracted encoded data.
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 a first syntax element for indicating a reference position in the pictures, and second and third 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 second and third syntax elements from the reference position indicated by the first syntax element, 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 included in 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 generating of the second bitstream comprises:
decoding the area information from the header of the first bitstream and determining whether an area on which partial decoding is to be performed is indicated by the area information; and
when the area on which partial decoding is to be performed is indicated by the area information, generating the second bitstream which is comprised of only encoded pixel data corresponding to the at least one area indicated by the area information.
5. The method of claim 1 , wherein the area information are included in the header of the first bitstream when NAL unit type information included in a NAL unit header of the first bitstream corresponds to a Video Coding Layer (VCL) or an Intra (I) slice.
6. The method of claim 1 ,
wherein the area information further includes information for indicating an additional area expanded from the area, and
wherein the additional area is defined as a proportion to a size of the at least one area or an absolute size.
7. A video decoding system for decoding a first bitstream received from an video encoding apparatus, the first bitstream including encoded pixel data in which each of pictures has been encoded with being split into a plurality of tiles and parameters used for encoding the pictures, each tile comprised of one or more coding tree units, the video decoding system comprising:
a bitstream generator configured to
receive 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 a first syntax element for indicating a reference position in the pictures, and second and third syntax elements for respectively indicating a width and a height from the reference position, and allows an area which includes two or more tiles, and
generate a to-be-decoded second bitstream, 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 second and third syntax elements from the reference position indicated by the first syntax element, 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 included in the area information; and
a video decoding apparatus configured to receive the second bitstream and thereby decode the extracted encoded pixel data.