Video processing methods and apparatuses in a video encoding or decoding system for processing a video picture partitioned into blocks with one or more partition constraints. The video encoding or decoding system receives input data of a current block and checks whether a predefined splitting type is allowed to partition the current block according to first and second constraints. The first constraint restricts each sub-block partitioned from the current block to be completely contained in one pipeline unit, and the second constraint restricts each sub-block partitioned from the current block to contain one or more complete pipeline units. The pipeline units are non-overlapping units in the video picture designed for pipeline processing. The current block is not partitioned by the predefined splitting type if any sub-block partitioned by the predefined splitting type violates both the first and second constraints. The system encodes or decodes the current block.