The post-processing algorithm consists of the deblocking and the deringing filters. Post-processing is a CPU-intensive process, which sometimes takes longer than decoding. You may not want to post-process, especially if you prefer the un-post-processed image, or if your PC is not powerful enough. To cater to users’ post-processing preferences, 6 different levels of post-processing have been defined. At the minimum (level 0), no post-processing algorithm is used; at the maximum (level 6), every clever algorithm is tried to enhance the appearance of your frames.
The human eye is less sensitive to the chrominance components of the video signal and more sensitive to the luminance components. For this reason, only the luminance plane is processed at lower post-processing levels, while higher levels activate the same algorithms on the chrominance planes. The post-processing algorithms used are activated in the following order: deblocking on luminance planes, deblocking on chrominance planes, deringing.
You can adjust postprocessing level in two ways. Either use the slider in configuration dialog of DivX DirectShow filter ( which can be accessed from Windows Media Player window while playing ) or in configuration dialog of encoder DLL. Both sliders do exactly the same thing.