Abstract: A motion compensating coder which includes a control section for setting quantizer step size accounts for both the buffer occupancy and the texture of the image being coded. The coding control method, using well-accepted assumptions relating to the human visual sensitivity to quantization distortion in an image, employs a recursive strategy that maintains a coding rate which closely approximates the number of target bits.

Abstract: A motion adaptive vertical filter is used to filter an interlaced video signal on a frame basis in areas of the image that are not in motion and on a field basis in areas that are in motion. A soft switch mixes the field filtered data and the frame filtered data in areas where there is relatively little motion to prevent artifacts which may be caused by abruptly switching between the two vertical filtering schemes. The frame vertical filter reduces the vertical resolution of still NTSC images to 180 cycles per picture height (CPH) while the field filter reduces the vertical resolution to 90 CPH.