Patent Number 6807365
Issue Date 2004 10 19
Assignee Matsushita Electric Industrial Co., Ltd.
Inventor(s) Aoki, Yoshito
Title: Video data recording and reproducing apparatus, a video data reproducing apparatus, and a method of recording and reproducing video data with data modification detection
Abstract: First modification detection data is generated from the (compressed) video data. The video data is combined with the first modification detection data. The combined data is recorded on a recording medium. The read combined data is separated into the compressed video data and the first modification detection data. Second modification detection data is generated according to the separated compressed data. The separated first data modification detection data is compared with the second data modification detection data to detect data modification. Outputting expanded video data is controlled according to the comparing result. The recorded data may be copied on a removable disc. A data reproducing apparatus having the second modification detection data generation circuit and the comparing circuit reproduces the removable disc. The reproduced video data may be further processed by a watermark processing circuit to embed watermark data in the video data which are recorded on another removable disc. The compressed video data may be transmitted through a network with encrypting. Encrypting key data is exchanged between the data transmitting side and the receiving side for decrypting. Encrypted video data may be recorded or transmitted and the encrypting key is stored for decrypting or transmitted for decrypting. Exmp. Claim 1 Ex Claim text A video data recording and reproducing apparatus comprising: data compression means for compressing video data; first modification detection data generation means for generating first modification detection data in accordance with said compressed video data; combining means for combining said video data with said first modification detection data to output combined data; recording means for recording said combined data on a recording medium; reading means for reading said combined data from said recording medium; separating means for separating said combined data from said reading means into said compressed video data and said first modification detection data; second modification detection data generation means for generating second modification detection data in accordance with said compressed data from said separating means; comparing means for comparing said data modification detection data from said separating means with said second data modification detection data; data expansion means for expanding said compressed video data from said separating means to output expanded video data; and outputting control means for controlling outputting said expanded video data in accordance with said result of said comparing means.