Methods of encoding a video stream in a video encoder and decoding an encoded video stream in a video decoder using a low complexity large transform are provided. An encoding method includes receiving an n×n residual block in a transform component of the video encoder, and transforming the n×n residual block using an n×n transform to generate an n×n transform coefficient block, wherein the n×n transform is based on (n/m*n/m) m×m Hadamard transforms and (m*m) (n/m)×(n/m) discrete cosign transforms, wherein m