Method and apparatus for video coding

Abstract

In a method of video decoding at a video decoder, a first high level syntax (HLS) element and a second HLS element can be received. The first HLS element can indicate whether an explicit multiple transform selection (MTS) is enabled or disabled for an intra coded block. The second HLS element can indicate whether the explicit MTS is enabled or disabled for an inter coded block. The first and second HLS elements can control a same set of coding blocks that include the intra coded block and the inter coded block. An implicit MTS can be enabled for the intra coded block when the first HLS element indicates the explicit MTS is disabled for the intra coded block, and the second HLS element indicates the explicit MTS is enabled for the inter coded block.

What is claimed is: 
     
         1 . A method for video processing, comprising:
 receiving a first high level syntax (HLS) element indicating whether an explicit multiple transform selection (MTS) is enabled or disabled for a first block that is an intra coded block, wherein transform type information indicating a transform type is signaled in the explicit MTS;   receiving a second HLS element indicating whether the explicit MTS is enabled or disabled for a second block that is an inter coded block; and   enabling an implicit MTS for the first block based on the first HLS element indicating the explicit MTS is disabled for the first block and irrespective of whether the second HLS element indicates the explicit MTS is enabled or disabled for the second block, wherein the transform type information is not signaled in the implicit MTS.   
     
     
         2 . The method of  claim 1 , further comprising:
 applying the implicit MTS to the intra coded block, wherein a transform type for processing the intra coded block is determined according to a size of the intra coded block.   
     
     
         3 . The method of  claim 1 , wherein the first or second HLS element is one of:
 a video parameter set (VPS) syntax element,   a sequence parameter set (SPS) syntax element,   a picture parameter set (PPS) syntax element,   a slice header syntax element,   a tile header syntax element, or   a tile group header syntax element.   
     
     
         4 . The method of  claim 1 , wherein the intra coded block is not coded with an intra sub-partitioning (ISP) mode. 
     
     
         5 . The method of  claim 1 , further comprising:
 receiving a third HLS element indicating an MTS is enabled for each of the inter and intra coded blocks.   
     
     
         6 . The method of  claim 1 , wherein the transform type information includes an MTS index, the MTS index signaling the transform type for the explicit MTS. 
     
     
         7 . The method of  claim 1 , wherein the enabling comprises:
 determining whether to enable the implicit MTS for the intra coded block based on whether a non-separable secondary transform (NSST) and a matrix-based intra prediction (MIP) are applied to the intra coded block.   
     
     
         8 . An apparatus for video processing, comprising circuitry configured to:
 receive a first high level syntax (HLS) element indicating whether an explicit multiple transform selection (MTS) is enabled or disabled for a first block that is an intra coded block, wherein transform type information indicating a transform type is signaled in the explicit MTS;   receive a second HLS element indicating whether the explicit MTS is enabled or disabled for a second block that is an inter coded block; and   enable an implicit MTS for the first block based on the first HLS element indicating the explicit MTS is disabled for the first block and irrespective of whether the second HLS element indicates the explicit MTS is enabled or disabled for the second block, wherein the transform type information is not signaled in the implicit MTS.   
     
     
         9 . The apparatus of  claim 8 , wherein the circuitry is further configured to:
 apply the implicit MTS to the intra coded block, wherein a transform type for processing the intra coded block is determined according to a size of the intra coded block.   
     
     
         10 . The apparatus of  claim 8 , wherein the first or second HLS element is one of:
 a video parameter set (VPS) syntax element,   a sequence parameter set (SPS) syntax element,   a picture parameter set (PPS) syntax element,   a slice header syntax element,   a tile header syntax element, or   a tile group header syntax element.   
     
     
         11 . The apparatus of  claim 8 , wherein the intra coded block is not coded with an intra sub-partitioning (ISP) mode. 
     
     
         12 . The apparatus of  claim 8 , wherein the circuitry is further configured to:
 receive a third HLS element indicating an MTS is enabled for each of the inter and intra coded blocks.   
     
     
         13 . The apparatus of  claim 8 , wherein the transform type information includes an MTS index, the MTS index signaling the transform type for the explicit MTS. 
     
     
         14 . The apparatus of  claim 8 , wherein the circuitry is further configured to:
 determine whether to enable the implicit MTS for the intra coded block based on whether a non-separable secondary transform (NSST) and a matrix-based intra prediction (MIP) are applied to the intra coded block.   
     
     
         15 . A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method for video processing, the method comprising:
 receiving a first high level syntax (HLS) element indicating whether an explicit multiple transform selection (MTS) is enabled or disabled for a first block that is an intra coded block, wherein transform type information indicating a transform type is signaled in the explicit MTS;   receiving a second HLS element indicating whether the explicit MTS is enabled or disabled for a second block that is an inter coded block; and   enabling an implicit MTS for the first block based on the first HLS element indicating the explicit MTS is disabled for the first block and irrespective of whether the second HLS element indicates the explicit MTS is enabled or disabled for the second block, wherein the transform type information is not signaled in the implicit MTS.   
     
     
         16 . The non-transitory computer-readable medium of  claim 15 , wherein the method further comprises:
 applying the implicit MTS to the intra coded block, wherein a transform type for processing the intra coded block is determined according to a size of the intra coded block.   
     
     
         17 . The non-transitory computer-readable medium of  claim 15 , wherein the first or second HLS element is one of:
 a video parameter set (VPS) syntax element,   a sequence parameter set (SPS) syntax element,   a picture parameter set (PPS) syntax element,   a slice header syntax element,   a tile header syntax element, or   a tile group header syntax element.   
     
     
         18 . The non-transitory computer-readable medium of  claim 15 , wherein the intra coded block is not coded with an intra sub-partitioning (ISP) mode. 
     
     
         19 . The non-transitory computer-readable medium of  claim 15 , wherein the transform type information includes an MTS index, the MTS index signaling the transform type for the explicit MTS. 
     
     
         20 . The non-transitory computer-readable medium of  claim 15 , wherein the enabling comprises:
 determining whether to enable the implicit MTS for the intra coded block based on whether a non-separable secondary transform (NSST) and a matrix-based intra prediction (MIP) are applied to the intra coded block.