Hybrid transform scheme for video coding

Abstract

Blocks of a frame are encoded by selected according to a hybrid symmetrical discrete sine transform scheme. For a residual block resulting from inter prediction, the residual block is respectively transformed using a discrete cosine transform (DCT) and a symmetrical discrete sine transform (SDST). A first rate-distortion value for encoding the residual block using the DCT and a second rate-distortion value for encoding the residual block using the SDST are generated. For a residual block generated by intra prediction, the residual block is respectively transformed using at least one transform mode, each of which is not the SDST. Multiple inter prediction and intra prediction modes may be considered to encode the current block. The transform mode and the prediction mode resulting in a lowest rate-distortion value for encoding the current block are selected, and the current block is encoded into an encoded bitstream using the selected modes.