Arbitrary spatial downsizing in H.264 to MPEG4 simple profile transcoder

We present a novel arbitrary spatial downsizing method in H.264 to MPEG4 simple profile transcoder. Using median filtering and scaling of input H.264 4times4 block level motion vectors, downsizing module generates target resolution compatible 4times4 block level motion vector, which is fed at MPEG4 encoder to generate MPEG4 compatible final 16times16 or 8times8 block level motion vector. Downsizing and encoding modules are differentiated for better portability. Our approach, being approximately 6-8 times faster compared to full encode system, achieves almost same compression as compared to full encoding.