SPRUHZ7K August 2015 – April 2024 AM5706 , AM5708 , AM5716 , AM5718 , AM5718-HIREL
When a poly-phase filter is used, usually it has to have many taps in order to achieve acceptable quality for very small downscaling ratio, which requires the use of many line buffers. In VIP, there is a weighted Running Average filter for downscaling when the scaling factor is small (for example, when the scaling ratio is less than 0.5). This highly optimized design requires only one line buffer for luma and one for chroma, which still achieving acceptable quality. The output of the running average filter is based on weighted average of pixels in the current and previous rows in vertical direction. Initializations of accumulators affect the weights.