| 摘要 |
PURPOSE:Not to reproduce a high-resolution video signal but to reproduce a low-resolution video signal when a cryptographic key is not suitable. CONSTITUTION:An analog HD signal 10 is converted to the encoded data of a normal-resolution video signal by an A/D converter 12, HD/SD conversion circuit 14 and encoder circuit 16. Those code data are converted again to high resolution by a decoder circuit 18 and an SD/-HD conversion circuit 20. A subtracter 22 subtracts the output of the SD/HD conversion circuit 20 from the output of the A/D converter 12 for each picture element and outputs the subtracted result as an auxiliary video signal. An encoder circuit 24 encodes the output of the subtracter 22, and a ciphering circuit 26 ciphers the output of the circuit 24 by using a cryptographic key 28. A multiplexer circuit 30 multiplexes the outputs of the circuits 16 and 26, and an output device 32 outputs the multiplexed data of the circuit 30 to a transmission line. |
