Quantized discrete cosine transform: a combination of DCT and scalar quantization

A typical MPEG-2 video encoder requires that DCT and quantization be performed in most cases. In this paper we show how to combine these two steps, reducing substantially the number of computations. The new nonlinear transform is called the quantized discrete cosine transform, or QDCT. We also introduce a new method to trade-off the computational complexity and the precision of the QDCT. Although the QDCT is independent of the input data, better trade-offs can be obtained by making it data dependent, which is appropriate in multimedia applications such as MPEG-2 video coding. The results presented in this paper can also be extended to other linear transforms and/or other coding methods