Method of constrained layer-wise video coding

Abstract

Method and apparatus of video coding using a multi-layer prediction mode, are disclosed. According to one method, a bitstream is generated at an encoder side or received at a decoder side, where the bitstream corresponds to coded data of current video data in a current layer. The bitstream complies with a bitstream conformance requirement corresponding both the bit depth values for the current layer and the reference layer being the same and the chroma format index values for the current layer and the reference layer being the same. The current video data in the current layer is then encoded or decoded by utilizing reference video data in the reference layer.

1 . A method for video coding, wherein a multi-layer prediction mode is supported, the method comprising:
 generating, at an encoder side, or receiving, at a decoder side, a bitstream corresponding to coded data of current video data in a current layer, wherein the bitstream complies with a bitstream conformance requirement comprising a first condition, a second condition, or both the first condition and the second condition, wherein the first condition corresponds to that first bit-depth for the current layer is greater than or equal to second bit-depth for a reference layer, wherein the second condition corresponds to that first chroma format index for the current layer is greater than or equal to second chroma format index for the reference layer, and wherein the first chroma format index and the second chroma format index specify chroma sampling relative to luma sampling for the current layer and the reference layer respectively, and a larger chroma format index value indicates a higher sub-sampling density; and   encoding, at the encoder side, or decoding at the decoder side, the current video data in the current layer by utilizing reference video data in the reference layer along with the first bit-depth and the second bit-depth, the first chroma format index and the second chroma format index, or both the first bit-depth and the second bit-depth and the first chroma format index and the second chroma format index.   
     
     
         2 . The method of  claim 1 , wherein the bit depth for the current layer and the reference layer are derived from bit_depth_minus8 syntax elements in the bitstream, and wherein the bit_depth_minus8 syntax elements correspond to the bit_depth_minus 8 for the current layer and the reference layer respectively. 
     
     
         3 . The method of  claim 1 , wherein the chroma format index for the current layer and the reference layer are determined according to chroma_format_idc syntax elements in the bitstream, and wherein the chroma_format_idc syntax elements specify chroma sampling relative to luma sampling for the current layer and the reference layer respectively. 
     
     
         4 . A method for coding a video sequence, wherein a multi-layer prediction mode is supported, the method comprising:
 receiving input data, wherein the input data correspond to video data in a current layer at a video encoder side or the input data correspond to coded video data in the current layer at a video decoder side; and   applying motion compensation to the video data in the current layer at the encoder side or to the coded video data in the current layer at the video decoder side by utilizing reference video data in a reference layer, wherein the motion compensation utilizes information comprising chroma formats or one or more variables related to the chroma format for both the current layer and the reference layer, bit-depth values for both the current layer and the reference layer, or both the chroma formats or said one or more variables related to the chroma format for both the current layer and the reference layer and the bit-depth values for both the current layer and the reference layer.   
     
     
         5 . The method of  claim 4 , wherein the bit-depth values are derived from syntax elements signaled in a bitstream or parsed from the bitstream, and wherein syntax elements correspond to the bit-depth values minus 8 for the current layer and the reference layer respectively. 
     
     
         6 . The method of  claim 4 , wherein the chroma formats or said one or more variables comprise a first variable corresponding to horizontal chroma sub-sampling factor, a second variable corresponding to vertical chroma sub-sampling factor, or both the first variable and the second variable. 
     
     
         7 . The method of  claim 6 , wherein a reference sample position of the reference layer is calculated in a motion compensation process by utilizing the horizontal chroma sub-sampling factor, the vertical chroma sub-sampling factor, or both. 
     
     
         8 . The method of  claim 6 , wherein a reference sample position of the reference layer is calculated in a motion compensation process by utilizing a first ratio of a first horizontal chroma sub-sampling factor of the current layer to a second horizontal chroma sub-sampling factor of the reference layer, a second ratio of a first vertical chroma sub-sampling factor of the current layer to a second vertical chroma sub-sampling factor of the reference layer, or both.