Fast video codec transform implementations

摘要

A fast implementation of the 8-point transform is realized using a sequence of butterfly operations and matrix multiplies. A fast implementation of the inverse transform is realized by applying inverses of the butterfly operations with the matrix multiplies in reverse flow. These fast implementations permit scaling to be incorporated into the transform stages either at the end of both dimensions of filtering, or separately at each stage. These fast implementations of the transform can be used in encoders and decoders based on this transform in image compression and other signal processing systems.