A transform video coder source model and its application

A source model describes the relationship between the bits, distortion, and quantization step sizes of a large class of block-transform video coder is proposed. This model is derived from rate-distortion theory, and verified by real images. It enables us to predict the bits needed to encode a picture for a given distortion or to adjust the quantization scales of a coder for a given bit rate. Based on this derived model, a variable frame rate coding algorithm is developed. It can be used to control the frame rate of a coder to ensure a minimum picture quality of every frame. Simulation results indicate that improved performance is obtained by using this variable frame rate coding scheme when compared to the simple approach of varying the quantization scale linearly proportional to the encoder buffer level