Block decoding method and system capable of rotating direction before decoding and outputting

This invention relates to one area decoding method and system output by rotation direction, which comprises one decoding device, one gear device, one anti-quantizer, one cosine device, one materials buffer area and one control device. The invention uses one dynamic set decoding window located on the decoding window for complete decoding and processes Hofmann decoding to the area without decoding window. When there are several rows of areas for output, then dynamically adjusting the decoding window position to get next area.