Patent ID: 8885714

Claim:
A method of intra-coding blocks of pixels in a digital video sequence, the method comprising: selecting a block transform of a plurality of block transforms according to a spatial prediction mode used in generating a block of pixel residual values from a block of pixels, wherein the block transform is based on a single directional transform matrix predetermined for the spatial prediction mode and is a same size as the block of pixel values, wherein the single directional transform matrix for carrying out a directional transform; applying the block transform to the block of pixel residual values to generate transform coefficients of the residual pixel values, wherein applying the block transform comprises computing a product of a sparse matrix, a DCT matrix, the block of pixel residual values, a transpose of the DCT matrix, and a transpose of the sparse matrix, wherein the sparse matrix is derived from the single directional transform matrix; and entropy coding the generated transform coefficients.