Abstract: A method and apparatus for Video Buffer Verifier (VBV) underflow and overflow control. A combination of picture and slice level control is used in the method and apparatus. Improved prevention of overflow and panic mode encoding is achieved by adjusting the virtual buffer-fullness which allows the quantization-step to have an improved response to the buffer-fullness at both high and low critical levels. The use of a non-linear quantization scheme and customised quantization matrices also provide improved prevention of panic mode encoding. The slice level control also reduces the computation complexity compared to the macroblock level control.