Signaling picture size in video coding

Abstract

A video encoder is configured to determine a picture size for one or more pictures included in a video sequence. The picture size associated with the video sequence may be a multiple of an aligned coding unit size for the video sequence. In one example, the aligned coding unit size for the video sequence may comprise a minimum coding unit size where the minimum coding unit size is selected from a plurality of smallest coding unit sizes corresponding to different pictures in the video sequence. A video decoder is configured to obtain syntax elements to determine the picture size and the aligned coding unit size for the video sequence. The video decoder decodes the pictures included in the video sequence with the picture size, and stores the decoded pictures in a decoded picture buffer.

1 . A method of encoding video data comprising:
 determining a smallest coding unit size for each of a plurality of pictures defining a video sequence, wherein a smallest coding unit size is selected from a plurality of possible coding unit sizes including a maximum possible coding unit size;   determining an aligned coding unit size for the video sequence based on the plurality of possible coding unit sizes;   determining a picture size associated with the video sequence, wherein the picture size associated with the video sequence is an multiple of the aligned coding unit size; and   signaling the aligned coding unit size value in sequence level syntax information.   
     
     
         2 . The method of  claim 1 , wherein the aligned coding unit size is the maximum possible coding unit size. 
     
     
         3 . The method of  claim 2 , wherein the plurality of possible coding unit sizes includes a maximum coding unit size of 64×64 pixels. 
     
     
         4 . The method of  claim 1 , wherein determining a smallest coding unit size for each of the plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the aligned coding unit size for the video sequence is 4×4 pixels. 
     
     
         5 . The method of  claim 1 , wherein determining a smallest coding unit size for each of the plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the aligned coding unit size for the video sequence is 8×8 pixels. 
     
     
         6 . The method of  claim 1 , wherein the picture size specifies a picture size of a decoded picture stored in a decoded picture buffer. 
     
     
         7 . A device configured to encode video data comprising:
 means for determining a smallest coding unit size for each of a plurality of pictures defining a video sequence, wherein a smallest coding unit size is selected from a plurality of possible coding unit sizes including a maximum possible coding unit size;   means for determining an aligned coding unit size for the video sequence based on the plurality of possible coding unit sizes;   means for determining a picture size associated with the video sequence, wherein the picture size associated with the video sequence is an multiple of the aligned coding unit size; and   means for signaling the aligned coding unit size value in sequence level syntax information.   
     
     
         8 . The device of  claim 7 , wherein the aligned coding unit size is the maximum possible coding unit size. 
     
     
         9 . The method of  claim 7 , wherein the plurality of possible coding unit sizes includes a maximum coding unit size of 64×64 pixels. 
     
     
         10 . The device of  claim 7 , wherein determining a smallest coding unit size for each of a plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the aligned coding unit size for the video sequence is 4×4 pixels. 
     
     
         11 . The device of  claim 7 , wherein determining a smallest coding unit size for each of a plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the aligned coding unit size for the video sequence is 8×8 pixels. 
     
     
         12 . The device of  claim 7 , wherein the picture size specifies a picture size of a decoded picture stored in a decoded picture buffer. 
     
     
         13 . A device comprising a video encoder configured to:
 determine a smallest coding unit size for each of a plurality of pictures defining a video sequence, wherein a smallest coding unit size is selected from a plurality of possible coding unit sizes including a maximum possible coding unit size;   determine an aligned coding unit size for the video sequence based on the plurality of possible coding unit sizes;   determine a picture size associated with the video sequence, wherein the picture size associated with the video sequence is an multiple of the aligned coding unit size; and   signal the aligned coding unit size value in sequence level syntax information.   
     
     
         14 . The device of  claim 13 , wherein the aligned coding unit size is the maximum possible coding unit size. 
     
     
         15 . The device of  claim 14 , wherein the plurality of possible coding unit sizes includes a maximum coding unit size of 64×64 pixels. 
     
     
         16 . The device of  claim 13 , wherein determining a smallest coding unit size for each of a plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the aligned coding unit size for the video sequence is 4×4 pixels. 
     
     
         17 . The device of  claim 13 , wherein determining a smallest coding unit size for each of a plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the aligned coding unit size for the video sequence is 8×8 pixels. 
     
     
         18 . The device of  claim 13 , wherein the picture size specifies a picture size of a decoded picture stored in a decoded picture buffer. 
     
     
         19 . A computer readable medium comprising instructions stored thereon that when executed cause a processor to:
 determine a smallest coding unit size for each of a plurality of pictures defining a video sequence, wherein a smallest coding unit size is selected from a plurality of possible coding unit sizes including a maximum possible coding unit size;   determine an aligned coding unit size for the video sequence based on the plurality of possible coding unit sizes;   determine a picture size associated with the video sequence, wherein the picture size associated with the video sequence is an multiple of the aligned coding unit size; and   signal the aligned coding unit size value in sequence level syntax information.   
     
     
         20 . The computer readable medium of  claim 19 , wherein the aligned coding unit size is the maximum possible coding unit size. 
     
     
         21 . The computer readable medium of  claim 20 , wherein the plurality of possible coding unit sizes includes a maximum coding unit size of 64×64 pixels. 
     
     
         22 . The computer readable medium of  claim 19 , wherein determining a smallest coding unit size for each of a plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the minimum coding unit size for the video sequence is 4×4 pixels. 
     
     
         23 . The computer readable medium of  claim 19 , wherein determining a smallest coding unit size for each of a plurality of pictures includes determining a first smallest coding unit size of 4×4 pixels for a first picture and determining a second smallest coding unit size of 8×8 pixels for a second picture; and wherein the minimum coding unit size for the video sequence is 8×8 pixels. 
     
     
         24 . The device of  claim 19 , wherein the picture size specifies a picture size of a decoded picture stored in a decoded picture buffer. 
     
     
         25 . A method of decoding video data comprising:
 obtaining a coded video sequence including a first picture coded using a first smallest coding unit size and a second picture coded using second smallest coding unit size;   obtaining a picture size of a decoded picture to be stored in a decoded picture buffer wherein the picture size is a multiple of one of the first coding unit size, the second coding unit size, or a maximum coding unit size; and   storing the decoded picture in a decoded picture buffer.   
     
     
         26 . The method of  claim 25 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the first coding unit size. 
     
     
         27 . The method of  claim 25 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the second coding unit size. 
     
     
         28 . The method of  claim 25 , wherein the maximum coding unit size is 64×64 pixels and the pictures size is a multiple of the maximum coding unit size. 
     
     
         29 . A device configured to decode video data comprising:
 means for obtaining a coded video sequence including a first picture coded using a first smallest coding unit size and a second picture coded using second smallest coding unit size;   means for obtaining a picture size of a decoded picture to be stored in a decoded picture buffer wherein the picture size is a multiple of one of the first coding unit size, the second coding unit size, or a maximum coding unit size; and   means for storing the decoded picture in a decoded picture buffer.   
     
     
         30 . The device of  claim 29 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the first coding unit size. 
     
     
         31 . The device of  claim 29 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the second coding unit size. 
     
     
         32 . The device of  claim 29 , wherein the maximum coding unit size is 64×64 pixels and the pictures size is a multiple of the maximum coding unit size. 
     
     
         33 . A device comprising a video decoder configured to:
 obtain a coded video sequence including a first picture coded using a first smallest coding unit size and a second picture coded using second smallest coding unit size;   obtain a picture size of a decoded picture to be stored in a decoded picture buffer wherein the picture size is a multiple of one of the first coding unit size, the second coding unit size, or a maximum coding unit size; and   store the decoded picture in a decoded picture buffer.   
     
     
         34 . The device of  claim 33 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the first coding unit size. 
     
     
         35 . The device of  claim 33 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the second coding unit size. 
     
     
         36 . The device of  claim 33 , wherein the maximum coding unit size is 64×64 pixels and the pictures size is a multiple of the maximum coding unit size. 
     
     
         37 . A computer readable medium comprising instructions stored thereon that when executed cause a processor to:
 obtain a coded video sequence including a first picture coded using a first smallest coding unit size and a second picture coded using second smallest coding unit size;   obtain a picture size of a decoded picture to be stored in a decoded picture buffer wherein the picture size is a multiple of one of the first coding unit size, the second coding unit size, or a maximum coding unit size; and   store the decoded picture in a decoded picture buffer.   
     
     
         38 . The computer readable medium of  claim 37 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the first coding unit size. 
     
     
         39 . The computer readable medium of  claim 37 , wherein the first smallest coding unit size is 4×4 pixels and the second coding unit size is 8×8 pixels and the pictures size is a multiple of the first coding unit size. 
     
     
         40 . The computer readable medium of  claim 37 , wherein the maximum coding unit size is 64×64 pixels and the pictures size is a multiple of the maximum coding unit size.