Video coding method using at least evaluated visual quality and related video coding apparatus

Abstract

One exemplary video coding method includes at least the following steps: utilizing a visual quality evaluation module for evaluating visual quality based on data involved in a coding loop; and referring to at least the evaluated visual quality for deciding a target configuration of at least one of a coding unit, a transform unit and a prediction unit. Another exemplary video coding method includes at least the following steps: utilizing a visual quality evaluation module for evaluating visual quality based on data involved in a coding loop; and referring to at least the evaluated visual quality for deciding a target coding parameter associated with at least one of a coding unit, a transform unit and a prediction unit in video coding.

What is claimed is: 
     
         1 . A video coding method, comprising:
 utilizing a visual quality evaluation module for evaluating visual quality based on data involved in a coding loop; and   referring to at least the evaluated visual quality for deciding a target configuration of at least one of a coding unit, a transform unit and a prediction unit.   
     
     
         2 . The video coding method of  claim 1 , wherein the data involved in the coding loop is raw data of a source frame. 
     
     
         3 . The video coding method of  claim 1 , wherein the data involved in the coding loop is processed data derived from raw data of a source frame. 
     
     
         4 . The video coding method of  claim 3 , wherein the processed data includes transformed coefficients, quantized coefficients, reconstructed pixel data, motion-compensated pixel data, or intra-predicted pixel data. 
     
     
         5 . The video coding method of  claim 1 , wherein the evaluated visual quality is derived from checking at least one image characteristic that affects human visual perception, and the at least one image characteristic includes sharpness, noise, blur, edge, dynamic range, blocking artifact, mean intensity, color temperature, scene composition, human face, animal presence, image content that attracts more or less interest, spatial masking, temporal masking, or frequency masking. 
     
     
         6 . The video coding method of  claim 1 , wherein the step of evaluating the visual quality comprises:
 calculating a single visual quality metric according to the data involved in the coding loop; and   determining each evaluated visual quality solely based on the single visual quality metric.   
     
     
         7 . The video coding method of  claim 1 , wherein the step of evaluating the visual quality comprises:
 calculating a plurality of distinct visual quality metrics according to the data involved in the coding loop; and   determining each evaluated visual quality based on the distinct visual quality metrics.   
     
     
         8 . The video coding method of  claim 7 , wherein the step of determining each evaluated visual quality based on the distinct visual quality metrics comprises:
 determining a plurality of weighting factors; and   determining each evaluated visual quality by combining the distinct visual quality metrics according to the weighting factors.   
     
     
         9 . The video coding method of  claim 8 , wherein the weighting factors are determined by training. 
     
     
         10 . The video coding method of  claim 1 , wherein the step of deciding the target configuration of at least one of the coding unit, the transform unit and the prediction unit comprises:
 deciding a best mode from different intra modes of the coding unit;   deciding a best mode from different inter modes of the coding unit; or   deciding that the coding unit is an intra-mode coding unit or an inter-mode coding unit.   
     
     
         11 . The video coding method of  claim 1 , wherein the step of deciding the target configuration of at least one of the coding unit, the transform unit and the prediction unit comprises:
 deciding a size of the prediction unit; or   deciding that the prediction unit is a symmetric prediction unit or an asymmetric prediction unit.   
     
     
         12 . The video coding method of  claim 1 , wherein the step of deciding the target configuration of at least one of the coding unit, the transform unit and the prediction unit comprises:
 deciding a size of the transform unit;   deciding a quad-tree depth of the transform unit; or   deciding that the transform unit is a residual quad-tree (RQT) transform unit or a non-square quad-tree (NSQT) transform unit.   
     
     
         13 . The video coding method of  claim 1 , further comprising:
 calculating pixel-based distortion based on at least a portion of raw data of a source frame and at least a portion of processed data derived from the raw data of the source frame;   wherein the step of deciding the target configuration of at least one of the coding unit, the transform unit and the prediction unit comprises:   deciding the target configuration of at least one of the coding unit, the transform unit and the prediction unit according to the evaluated visual quality and the pixel-based distortion.   
     
     
         14 . The video coding method of  claim 13 , wherein the step of deciding the target configuration of at least one of the coding unit, the transform unit and the prediction unit according to the evaluated visual quality and the pixel-based distortion comprises:
 performing a coarse decision according to one of the evaluated visual quality and the pixel-based distortion to determine a plurality of coarse configuration settings; and   performing a fine decision according to another of the evaluated visual quality and the pixel-based distortion to determine at least one fine configuration setting from the coarse configuration settings, wherein the target configuration is derived from the at least one fine configuration setting.   
     
     
         15 . A video coding method, comprising:
 utilizing a visual quality evaluation module for evaluating visual quality based on data involved in a coding loop; and   referring to at least the evaluated visual quality for deciding a target coding parameter associated with at least one of a coding unit, a transform unit and a prediction unit in video coding.   
     
     
         16 . The video coding method of  claim 15 , wherein the target coding parameter is a quantization parameter or a transform parameter. 
     
     
         17 . The video coding method of  claim 15 , wherein the data involved in the coding loop is raw data of a source frame. 
     
     
         18 . The video coding method of  claim 15 , wherein the data involved in the coding loop is processed data derived from raw data of a source frame. 
     
     
         19 . The video coding method of  claim 18 , wherein the processed data includes transformed coefficients, quantized coefficients, reconstructed pixel data, motion-compensated pixel data, or intra-predicted pixel data. 
     
     
         20 . The video coding method of  claim 15 , wherein the evaluated visual quality is derived from checking at least one image characteristic that affects human visual perception, and the at least one image characteristic includes sharpness, noise, blur, edge, dynamic range, blocking artifact, mean intensity, color temperature, scene composition, human face, animal presence, image content that attracts more or less interest, spatial masking, temporal masking, or frequency masking. 
     
     
         21 . The video coding method of  claim 15 , wherein the step of evaluating the visual quality comprises:
 calculating a single visual quality metric according to the data involved in the coding loop; and   determining each evaluated visual quality solely based on the single visual quality metric.   
     
     
         22 . The video coding method of  claim 15 , wherein the step of evaluating the visual quality comprises:
 calculating a plurality of distinct visual quality metrics according to the data involved in the coding loop; and   determining each evaluated visual quality based on the distinct visual quality metrics.   
     
     
         23 . The video coding method of  claim 22 , wherein the step of determining each evaluated visual quality based on the distinct visual quality metrics comprises:
 determining a plurality of weighting factors; and   determining each evaluated visual quality by combining the distinct visual quality metrics according to the weighting factors.   
     
     
         24 . The video coding method of  claim 23 , wherein the weighting factors are determined by training. 
     
     
         25 . The video coding method of  claim 15 , further comprising:
 calculating pixel-based distortion based on at least a portion of raw data of a source frame and at least a portion of processed data derived from the raw data of the source frame;   wherein the step of deciding the target coding parameter comprises:   deciding the target coding parameter according to the evaluated visual quality and the pixel-based distortion.   
     
     
         26 . The video coding method of  claim 25 , wherein the step of deciding the target coding parameter according to the evaluated visual quality and the pixel-based distortion comprises:
 performing a coarse decision according to one of the evaluated visual quality and the pixel-based distortion to determine a plurality of coarse parameter settings; and   performing a fine decision according to another of the evaluated visual quality and the pixel-based distortion to determine at least one fine parameter setting from the coarse parameter settings, wherein the target coding parameter is derived from the at least one fine parameter setting.   
     
     
         27 . The video coding method of  claim 15 , wherein the target coding parameter is included in a bitstream generated by encoding a source frame. 
     
     
         28 . A video coding apparatus, comprising:
 a visual quality evaluation module, arranged to evaluate visual quality based on data involved in a coding loop; and   a coding circuit, comprising the coding loop, the coding circuit arranged to refer to at least the evaluated visual quality for deciding a target configuration of at least one of a coding unit, a transform unit and a prediction unit.   
     
     
         29 . A video coding apparatus, comprising:
 a visual quality evaluation module, arranged to evaluate visual quality based on data involved in a coding loop; and   a coding circuit, comprising the coding loop, the coding circuit arranged to refer to at least the evaluated visual quality for deciding a target coding parameter associated with at least one of a coding unit, a transform unit and a prediction unit in video coding.