Recursive Integer Cosine Transform for HEVC and Future Video Coding Standards

A method to derive an order-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sup> integer cosine transform is presented in this paper. The proposed transform has orthogonal basis vectors and inherits the recursive structure from the discrete cosine transform such that an order-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sup> transform can be derived from an order-2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(N-1</sup> transform. In this paper, transforms up to order 32 are derived and implemented into High Efficiency Video Coding reference model HM13.0. Compared with the core transform in HM13.0, the proposed transform has more flexibility and lower complexity for implementation while providing almost the same coding performance.