Low bit rate video coding using DCT-based fast decimation/interpolation and embedded zerotree coding

We present a low bit rate video coding procedure in the discrete cosine transform (DCT) domain that is based on fast decimation and interpolation and on embedded zerotree coding algorithms. The theory for decimation/interpolation in the DCT domain is given, and we show how to obtain fast algorithms. Motivated by the compositing of several video sources in multi-point video conferencing, we come up with a new method for single video streams that uses the proposed DCT-decimation in the encoder and the corresponding interpolation in the decoder. The decimated video frames are encoded using an embedded zerotree and an adaptive arithmetic coder to improve the quality of the decoded video and at an exact bit rate. The decimation and interpolation can be done with integer or rational factors, allowing flexibility in choosing the bit rate. Our codec performance is illustrated using different decimation factors, and it is shown that this codec is particularly efficient for low bit rates.