Video encoding and decoding

Abstract

A decoder can be configured to decode a picture from a bitstream in which the picture is partitioned into a plurality of tile groups. The decoder can decode a first part of the bitstream (including parameter set data) to form a size mapping that maps a tile group index value to a number of tiles to be decoded for a first tile group. The decoder can further decode a second part of the bitstream (including includes coded tile groups) by: decoding, from a tile group header in a first coded tile group, a first tile group index value for the first tile group; determining a first size for the first tile group based on the first tile group index value and the size mapping; and decoding a number of coded tiles to form the decoded picture, the number of coded tiles being equal to the first size.

What is claimed is: 
     
         1 . A method of operating a decoder to decode a picture from a bitstream, the picture being partitioned into a plurality of tile groups, the method comprising:
 decoding a first part of the bitstream to form a size mapping that maps a tile group index value to a number of tiles to be decoded for a first tile group, the first part of the bitstream including parameter set data,; and   decoding a second part of the bitstream that includes coded tile groups,   wherein decoding the second part of the bitstream comprises decoding a first coded tile group corresponding to the first tile group, and   wherein decoding the first coded tile group comprises:
 decoding, from a tile group header in the first coded tile group, a first tile group index value for the first tile group; 
 determining a first size for the first tile group based on the first tile group index value and the size mapping; and 
 decoding a number of coded tiles to form the decoded picture, the number of coded tiles being equal to the first size. 
   
     
     
         2 . The method of  claim 1 , wherein the size mapping includes one or more of an array and/or list and a parallel set of arrays and/or lists. 
     
     
         3 . The method of  claim 1 , wherein decoding the first part of the bitstream to form the size mapping comprises:
 decoding from the bitstream a first value indicating a number of list values; and   forming a list by decoding from the bitstream a number of list values, the number of list values being equal to the first value.   
     
     
         4 . The method of  claim 1 , further comprising:
 decoding from the bitstream a first value indicating a number of list values;   forming a first list (KEY) and a second list (VALUE) by decoding from the bitstream a number of values representing key-value pairs k and v, the number of key-value pairs being equal to the first value, the first list including the keys k and the second list includes the values v of the key-value pairs, and an ordering of the first list and the second list being such that for a given key-value pair, an index for the given key k in the first list corresponds to an index for the given value v in the second list; and   determining an index (i) such that the value corresponding to the index in the first list (KEY[i]) matches the first tile group index value.   
     
     
         5 . The method of  claim 1 , wherein determining the first size for the first tile group based on the first tile group index value and the size mapping comprises performing a lookup operation using the first tile group index value. 
     
     
         6 . The method of  claim 1 , wherein a tile group comprises one or more tiles. 
     
     
         7 . The method of  claim 1 , wherein a tile group comprises only one tile. 
     
     
         8 . A method of operating an encoder to encode a picture into a bitstream, the picture being partitioned into a plurality of tile groups, the method comprising:
 determining a size mapping that maps a tile group index value to a number of tiles to be encoded for a first tile group;   encoding a first part of the bitstream that includes parameter set data; and   encoding a second part of the bitstream that includes coded tile groups,   wherein encoding the first part of the bitstream comprises generating parameter set code words forming the size mapping that maps a tile group index value to a number of tiles to be encoded for the first tile group,   wherein encoding the second part of the bitstream comprises encoding a first tile group into a coded tile group, and   wherein encoding the first tile group into the coded tile group comprises:
 determining a first tile group index value for the first tile group, the size mapping mapping the first tile group index value for the first tile group to a first size, the first size being a number of tiles to be encoded into the coded tiles for the first tile group; 
 encoding the first tile group index value for the first tile group into one or more tile group header code words representing the first tile group index value; and 
 encoding a number of tiles for the first tile group into coded tiles, the number of tiles being equal to the first size. 
   
     
     
         9 . The method of  claim 8 , wherein the size mapping includes one or more of an array and/or list and a parallel set of arrays and/or lists. 
     
     
         10 . The method of  claim 8 , wherein a tile group comprises one or more tiles. 
     
     
         11 . The method of  claim 8 , wherein a tile group comprises only one tile. 
     
     
         12 . A decoder configured to decode a picture from a bitstream, the picture being partitioned into a plurality of tile groups, the decoder comprising:
 processing circuitry; and   memory coupled to the processing circuitry and having instructions stored therein that are executable by the processing circuitry to cause the decoder to perform operations comprising:   decoding a first part of the bitstream to form a size mapping that maps a tile group index value to a number of tiles to be decoded for a first tile group, the first part of the bitstream including parameter set data; and   decoding a second part of the bitstream that includes coded tile groups,   wherein decoding the second part of the bitstream comprises decoding a first coded tile group corresponding to the first tile group, and   wherein decoding the first part of the bitstream comprises:
 decoding, from a tile group header in the first coded tile group, a first tile group index value for the first tile group; 
 determining a first size for the first tile group based on the first tile group index value and the size mapping; and 
 decoding a number of coded tiles to form the decoded picture, the number of coded tiles being equal to the first size. 
   
     
     
         13 . The decoder of  claim 12 , wherein the size mapping includes one or more of an array and/or list and a parallel set of arrays and/or lists. 
     
     
         14 . The decoder of  claim 12 , wherein decoding the first part of the bitstream to form the size mapping comprises:
 decoding from the bitstream a first value indicating a number of list values; and   forming a list by decoding from the bitstream a number of list values, the number of list values being equal to the first value.   
     
     
         15 . The decoder of  claim 12 , the operations further comprising:
 decoding from the bitstream a first value indicating a number of list values;   forming a first list (KEY) and a second list (VALUE) by decoding from the bitstream a number of values representing key-value pairs k and v, the number of key-value pairs being equal to the first value, the first list including the keys k and the second list includes the values v of the key-value pairs, and an ordering of the first list and the second list being such that for a given key-value pair, an index for the given key k in the first list corresponds to an index for the given value v in the second list; and   determining an index (i) such that the value corresponding to the index in the first list (KEY[i]) matches the first tile group index value.   
     
     
         16 . The decoder of  claim 12 , wherein determining the first size for the first tile group based on the first tile group index value and the size mapping comprises performing a lookup operation using the first tile group index value. 
     
     
         17 . An encoder configured to encode a picture into a bitstream, the picture being partitioned into a plurality of tile groups, the decoder comprising:
 processing circuitry; and   memory coupled to the processing circuitry and having instructions stored therein that are executable by the processing circuitry to cause the encoder to perform operations comprising:   determining a size mapping that maps a tile group index value to a number of tiles to be encoded for a first tile group;   encoding a first part of the bitstream that includes parameter set data; and   encoding a second part of the bitstream that includes coded tile groups,   wherein encoding the first part of the bitstream comprises generating parameter set code words forming the size mapping that maps a tile group index value to a number of tiles to be encoded for the first tile group,   wherein encoding the second part of the bitstream comprises encoding a first tile group into a coded tile group, and   wherein encoding the first tile group into the coded tile group comprises:
 determining a first tile group index value for the first tile group, the size mapping mapping the first tile group index value for the first tile group to a first size, the first size being a number of tiles to be encoded into the coded tiles for the first tile group; 
 encoding the first tile group index value for the first tile group into one or more tile group header code words representing the first tile group index value; and 
 encoding a number of tiles for the first tile group into coded tiles, the number of tiles being equal to the first size. 
   
     
     
         18 . The encoder of  claim 17 , wherein the size mapping includes one or more of an array and/or list and a parallel set of arrays and/or lists. 
     
     
         19 . A non-transitory computer-readable medium having instructions stored therein that are executable by processing circuitry of a decoder to cause the decoder to perform operations, the decoder configured to decode a picture from a bitstream, the picture being partitioned into a plurality of tile groups, the operations comprising:
 decoding a first part of the bitstream to form a size mapping that maps a tile group index value to a number of tiles to be decoded for a first tile group, the first part of the bitstream including parameter set data; and   decoding a second part of the bitstream that includes coded tile groups,   wherein decoding the second part of the bitstream comprises decoding a first coded tile group corresponding to the first tile group, and   wherein decoding the first part of the bitstream comprises:
 decoding, from a tile group header in the first coded tile group, a first tile group index value for the first tile group; 
 determining a first size for the first tile group based on the first tile group index value and the size mapping; and 
 decoding a number of coded tiles to form the decoded picture, the number of coded tiles being equal to the first size. 
   
     
     
         20 . A non-transitory computer-readable medium having instructions stored therein that are executable by processing circuitry of an encoder to cause the encoder to perform operations, the encoder configured to encode a picture into a bitstream, the picture being partitioned into a plurality of tile groups, the operations comprising:
 determining a size mapping that maps a tile group index value to a number of tiles to be encoded for a first tile group;   encoding a first part of the bitstream that includes parameter set data; and   encoding a second part of the bitstream that includes coded tile groups,   wherein encoding the first part of the bitstream comprises generating parameter set code words forming the size mapping that maps a tile group index value to a number of tiles to be encoded for the first tile group,   wherein encoding the second part of the bitstream comprises encoding a first tile group into a coded tile group, and   wherein encoding the first tile group into the coded tile group comprises:
 determining a first tile group index value for the first tile group, the size mapping mapping the first tile group index value for the first tile group to a first size, the first size being a number of tiles to be encoded into the coded tiles for the first tile group; 
 encoding the first tile group index value for the first tile group into one or more tile group header code words representing the first tile group index value; and 
 encoding a number of tiles for the first tile group into coded tiles, the number of tiles being equal to the first size.