An apparatus, a method, and a computer-readable medium having instructions encoded thereon that when executed cause a method to be carried out. The method includes dividing at least a portion of a picture of a video stream into parts of blocks, and processing the parts in parallel by a plurality of interconnected processors. The processing of a respective part by its respective processor includes determining block-level temporal difference features. Each processor also performs coding functions on its respective part of the picture. The method also includes block-level processing using the block-level temporal difference features to determine which blocks in the picture are likely to be that of a face, the block-level processing being at the granularity of at least a block. In one version, the processing in each processor includes edge detection and color segmentation to determine block-level edge features including block-level color-segmented edge features that are then used in the block level processing.