A Content-Dependent Fast DCT for Low Bit-Rate Video Coding

A new content-dependent fast discrete cosine transform (DCT) algorithm is introduced. Since it requires less than half of the samples of an 8 8 block as input and produces only the rst three DCT coe cients, it is far less complex than conventional full fast DCT algorithms. It is shown that these three coe cients are su cient for the majority of the blocks for motion-compensated low bit-rate video coding. For other blocks, a conventional full-coe cient DCT is employed. Experiments with both low and high complexity sequences show that the content-dependent algorithm reduces the computational load of the DCT by a factor > 2 without loss in image quality and a factor 4 , if a slight PSNR loss is acceptable. In Proc. IEEE Int. Conf. on Imag. Processing, Oct. 98, Chicago