Method and apparatus for intra prediction using an interpolation filter

A decoding device, comprising:

• at least one processor;
• and
• one or more memories coupled to the at least one processor and storing programming instructions for execution by the at least one processor to cause the decoding device to:
• perform entropy decoding, inverse quantization and inverse transformation on a bitstream, to obtain residual information;
• perform an intra-prediction process of a block comprising samples to be predicted, to obtain predicted sample values of the block, wherein an interpolation filter is applied to reference samples of the block during the intra-prediction process of the block;
• and
• obtain reconstructed sample values of the block according to the residual information and the predicted sample values of the block;
• wherein the interpolation filter is selected from a set of interpolation filters used for the intra-prediction process on the basis of a non-integer part of an offset between the reference samples and the samples to be predicted;
• and
• wherein a size of a main reference side used in the intra-prediction process is determined according to a length of the interpolation filter and an intra-prediction mode that provides, out of a set of available intra-prediction modes, the greatest non-integer value of a maximum subpixel offset, the greatest non-integer value of the maximum subpixel offset being a greatest value of offsets between the reference samples and the samples to be predicted that occur in the intra-prediction process of the block by means of the available intra-prediction modes, and the main reference side comprises the reference samples.

A non-transitory computer-readable medium storing computer instructions for video decoding, that when executed by one or more processors, cause the one or more processors to perform operations comprising:

• performing entropy decoding, inverse quantization and inverse transformation on a bitstream, to obtain residual information;
• performing an intra-prediction process of a block comprising samples to be predicted, to obtain predicted sample values of the block, wherein an interpolation filter is applied to reference samples of the block during the intra-prediction process of the block;
• and
• obtaining reconstructed sample values of the block according to the residual information and the predicted sample values of the block;
• wherein the interpolation filter is selected from a set of interpolation filters used for the intra-prediction process on the basis of a non-integer part of an offset between the reference samples and the samples to be predicted;
• and
• wherein a size of a main reference side used in the intra-prediction process is determined according to a length of the interpolation filter and an intra-prediction mode that provides, out of a set of available intra-prediction modes, the greatest non-integer value of a maximum subpixel offset, the greatest non-integer value of the maximum subpixel offset being a greatest value of offsets between the reference samples and the samples to be predicted that occur in the intra-prediction process of the block by means of the available intra-prediction modes, and the main reference side comprises the reference samples.

A non-transitory computer readable storage medium having an encoded bitstream for a video signal, the encoded bitstream is decoded using a video decoding method, wherein the video decoding method comprises:

• performing entropy decoding, inverse quantization and inverse transformation on a bitstream, to obtain residual information;
• performing an intra-prediction process of a block comprising samples to be predicted, to obtain predicted sample values of the block, wherein an interpolation filter is applied to reference samples of the block during the intra-prediction process of the block;
• and
• obtaining reconstructed sample values of the block according to the residual information and the predicted sample values of the block;
• wherein the interpolation filter is selected from a set of interpolation filters used for the intra-prediction process on the basis of a non-integer part of an offset between the reference samples and the samples to be predicted;
• and
• wherein a size of a main reference side used in the intra-prediction process is determined according to a length of the interpolation filter and an intra-prediction mode that provides, out of a set of available intra-prediction modes, the greatest non-integer value of a maximum subpixel offset, the greatest non-integer value of the maximum subpixel offset being a greatest value of offsets between the reference samples and the samples to be predicted that occur in the intra-prediction process of the block by means of the available intra-prediction modes, and the main reference side comprises the reference samples.