Method and apparatus for low-complexity bi-directional intra prediction in video encoding and decoding

A method for video encoding, comprising:

• obtaining a directional intra prediction mode for a block of a picture in a video, said directional intra prediction mode having a direction;
• obtaining, based on said directional intra prediction mode, a first predictor for a sample, the sample being within said block;
• determining a displacement value along an array of reference samples, based on said direction, using integer-based operations, wherein said displacement value is determined using a magnitude value for an angle parameter associated with said direction of said directional intra prediction mode from a set of available directional intra prediction modes, and wherein said magnitude value is determined by N/A, where A is said angle parameter associated with said direction and N is a power of 2, wherein said power depends on a sample accuracy of said direction;
• identifying a second predictor for said sample based on said displacement value, said first and second predictors being on a line along or approximating said direction, wherein said sample is substantially located on said line, between said first and second predictors, said second predictor being substantially at an intersection of said line and said array of reference samples;
• predicting a sample value of said sample, by using said first and second predictors;
• and
• encoding said sample of said block based on said predicted sample value.

An apparatus for video decoding, comprising one or more processors and at least one memory, wherein said one or more processors are configured to:

• decode a directional intra prediction mode for a block of a picture in a video, said directional intra prediction mode having a direction;
• obtain, based on said directional intra prediction mode, a first predictor for a sample, the sample being within said block;
• determine a displacement value along an array of reference samples, based on said direction, using integer-based operations, wherein said displacement value is determined using a magnitude value for an angle parameter associated with said direction of said directional intra prediction mode from a set of available directional intra prediction modes, and wherein said magnitude value is determined by N/A, where A is said angle parameter associated with said direction and N is a power of 2, wherein said power depends on a sample accuracy of said direction;
• identify a second predictor for said sample based on said displacement value, said first and second predictors being on a line along or approximating said direction, wherein said sample is substantially located on said line, between said first and second predictors, said second predictor being substantially at an intersection of said line and said array of reference samples;
• predict a sample value of said sample, by using said first and second predictors;
• and
• decode said sample of said block based on said predicted sample value.

An apparatus for video decoding, comprising one or more processors and at least one memory, wherein said one or more processors are configured to:

• obtain a directional intra prediction mode for a block of a picture in a video, said directional intra prediction mode having a direction;
• obtain, based on said directional intra prediction mode, a first predictor for a sample, the sample being within said block;
• determine a displacement value along an array of reference samples, based on said direction, using integer-based operations, wherein said displacement value is determined using a magnitude value for an angle parameter associated with said direction of said directional intra prediction mode from a set of available directional intra prediction modes, and wherein said magnitude value is determined by N/A, where A is said angle parameter associated with said direction and N is a power of 2, wherein said power depends on a sample accuracy of said direction;
• identify a second predictor for said sample based on said displacement value, said first and second predictors being on a line along or approximating said direction, wherein said sample is substantially located on said line, between said first and second predictors, said second predictor being substantially at an intersection of said line and said array of reference samples;
• predict a sample value of said sample, by using said first and second predictors;
• and
• encode said sample of said block based on said predicted sample value.