Video encoding methods and systems using adaptive color transform

Abstract

A video encoding method includes receiving a source video frame, dividing the source video frame into a coding tree unit, determining a coding unit from the coding tree unit, determining a correlation between components of the coding unit, enabling or disabling a coding mode of the coding unit, determining whether to evaluate a size of a transform unit for an enabled coding mode, and determining a transform unit of the coding unit for the enabled coding mode, wherein the size of the coding unit is defined by a number (N) of samples.

What is claimed is: 
     
         1 . A video encoding method comprising:
 receiving a source video frame;   dividing the source video frame into a coding tree unit;   determining a coding unit from the coding tree unit;   determining a correlation between components of the coding unit;   enabling or disabling a coding mode of the coding unit;   determining whether to evaluate a size of a transform unit for an enabled coding mode; and   determining a transform unit of the coding unit for the enabled coding mode;   wherein the size of the coding unit is defined by a number (N) of samples.   
     
     
         2 . The method of  claim 1 , wherein:
 determining a correlation between components of the coding unit comprises determining a color space of the coding unit.   
     
     
         3 . The method of  claim 2 , wherein:
 determining the color space comprises determining whether the color space is a red, green, and blue (RGB) color space or a luminance and chrominance (YUV) color space.   
     
     
         4 . The method of  claim 3 , further comprising:
 enabling, if the enabled coding mode is an intra prediction mode which enables an adaptive color transform, a cost-based mode decision when the color space is determined to be an RGB color space.   
     
     
         5 . The method of  claim 3 , further comprising:
 disabling, if the enabled coding mode is an intra prediction mode which enables an adaptive color transform, a cost-based decision when the color space is determined to be a YUV color space.   
     
     
         6 . The method of  claim 3 , further comprising
 disabling a coding mode of the coding unit when the color space is determined to be a YUV color space and N is greater than or equal to a threshold.   
     
     
         7 . The method of  claim 3 , further comprising
 determining whether N is smaller than a threshold; and   enabling, when the color space is determined to be a YUV color space and N is smaller than the threshold, a coding mode which enables an adaptive color transform   
     
     
         8 . The method of  claim 1 , further comprising:
 determining whether N is greater than or equal to a threshold; and   determining, when N is greater than or equal to the threshold and the enabled coding mode is a coding mode which enables an adaptive color transform, not to evaluate the size of the transform unit.   
     
     
         9 . The method of  claim 1 , further comprising:
 determining whether N is smaller than a threshold; and   evaluating, when N is smaller than the threshold and the enabled coding mode is a coding mode which enables an adaptive color transform, a size of the transform unit.   
     
     
         10 . The method of  claim 9 , further comprising:
 selecting the size of the transform unit.   
     
     
         11 . The method of  claim 1 , further comprising:
 determining whether N is smaller than a first threshold;   determining whether N is smaller than a second threshold;   enabling, when the color space is determined to be a YUV color space and when N is smaller than the first threshold, a coding mode which enables an adaptive color transform; and   evaluating a size of the transform unit for the coding mode which enables the adaptive color transform when N is smaller than the second threshold.   
     
     
         12 . The method of  claim 1 , further comprising:
 determining whether N is smaller than a first threshold;   determining whether N is greater than or equal to a second threshold;   enabling, when the color space is determined to be a YUV color space and when N is smaller than the first threshold, a coding mode which enables an adaptive color transform; and   determining not to evaluate the size of the transform unit for the coding mode which enables the adaptive color transform when N is greater than or equal to the second threshold.   
     
     
         13 . The method of  claim 1 , wherein:
 N equals a number of horizontal samples or a number of vertical samples.   
     
     
         14 . The method of  claim 1 , wherein:
 determining a correlation between components of the coding unit comprises comparing a correlation of pixel components to a threshold.   
     
     
         15 . A video encoding system comprising:
 a memory storing instructions; and   a processor configured to execute the instructions to:
 receive a source video frame; 
 divide the source video frame into a coding tree unit; 
 determine a coding unit from the coding tree unit; 
 determine a correlation between components of the coding unit; 
 enable or disable a coding mode of the coding unit; 
 determine whether to evaluate a size of a transform unit for an enabled coding mode; and 
 determine a transform unit of the coding unit for the enabled coding mode; 
 wherein the size of the coding unit is defined by a number (N) of samples. 
   
     
     
         16 . The system of  claim 15 , wherein the processor is further configured to execute instructions to:
 determine the correlation between components of the coding unit by determining a color space of the coding unit.   
     
     
         17 . The system of  claim 16 , wherein the processor is further configured to execute instructions to:
 determine the color space by determining whether the color space is a red, green, and blue (RGB) color space or a luminance and chrominance (YUV) color space.   
     
     
         18 . The system of  claim 15 , wherein the processor is further configured to execute instructions to:
 determine whether N is smaller than a first threshold;   determine whether N is smaller than a second threshold;   enable, when the color space is determined to be a YUV color space and when N is smaller than the first threshold, a coding mode which enables an adaptive color transform, and   evaluate a size of the transform unit for the coding mode which enables the adaptive color transform when N is smaller than the second threshold.   
     
     
         19 . The system of  claim 15 , wherein the processor is further configured to execute instructions to:
 determine whether N is smaller than a first threshold;   determine whether N is greater than or equal to a second threshold;   enable, when the color space is determined to be a YUV color space and when N is smaller than the first threshold, a coding mode which enables an adaptive color transform, and   determine not to evaluate the size of the transform unit for the coding mode which enables the adaptive color transform when N is greater than or equal to the second threshold.   
     
     
         20 . A non-transitory computer-readable storage medium storing a set of instructions that, when executed by one or more processors, cause the one or more processors to perform a method of video encoding, the method comprising:
 receiving a source video frame;   dividing the source video frame into a coding tree unit;   determining a coding unit from the coding tree unit;   determining a correlation between components of the coding unit;   enabling or disabling a coding mode of the coding unit;   determining whether to evaluate a size of a transform unit for an enabled coding mode; and   determining a transform unit of the coding unit for the enabled coding mode;   wherein the size of the coding unit is defined by a number (N) of samples.