| 摘要 |
Unauthorized copying of a video signal is prevented by means of a compression encoding circuit that selectively applies scrambling to the encoded signal. The compression encoding circuit is of the type which divides frames of a digital video signal into rectangular data blocks, aggregates a predetermined number of data blocks to form macroblocks, shuffles the macroblocks within the video frame, and performs discrete cosine transform processing block-by-block on the rectangular data blocks making up the shuffled macroblocks. The scrambling may be accomplished by rearranging the order of the rectangular data blocks within each macroblock, or by changing the pattern according to which macroblocks are shuffled in the video frames. The scrambling may also be accomplished by interchanging bits in a component, such as the DC component, of the DCT-processed data, or by setting such data bits to predetermined values. A compression encoding circuit with the above-described scrambling capability may be used in a digital video tape recorder (VTR), and the scrambling capability may be activated in response to a copyright protection signal present in an analog video signal supplied as an input to the digital VTR. i |
