Video data recording and reproducing apparatus, a video data reproducing apparatus, and a method of recording and reproducing video data with data modification detection

A video data reproducing apparatus for reproducing combined data including compressed video data and first modification detection data on a removable recording medium, said video data being recorded with first modification detection data generated in accordance with said video data with correspondence with said video data, comprising:

• reading means for reading said combined data from said removable recording medium;
• separating means for separating said combined data from said reading means into said compressed video data and said first modification detection data;
• 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.

A method of detecting modification comprising the steps of:

• generating first modification detection data in accordance with said compressed video data;
• correspondingly recording said compressed video data and said modification detection data on a recording medium;
• reading means for reading said compressed video data and said first modification detection data from said recording medium;
• generating second data modification detection data in accordance with said read compressed data;
• comparing said read first data modification detection data with said second data modification detection data;
• and
• controlling reproducing said compressed data in accordance with said comparing result.

A video data recording and reproducing apparatus comprising:

• first modification detection data generation means for generating first modification detection data from video data;
• recording means for correspondingly recording said video data and said first modification detection data on a recording medium;
• reading means for reading said video data and said first modification detection data from said recording medium;
• second modification detection data generation means for generating second modification detection data in accordance with said video data from said reading means;
• comparing means for comparing said first data modification detection data from said reading means with said second data modification detection data;
• and
• outputting control means for controlling outputting said video data from said reading means in accordance with said result of said comparing means.

A video data reproducing apparatus comprising:

• receiving means for receiving video data and first modification detection data generated in accordance with said video data;
• modification detection data generation means for generating second modification detection data in accordance with said video data from said receiving means;
• comparing means for comparing said first modification detection data from said receiving means with said second data modification detection data;
• and
• outputting control means for controlling outputting said video data in accordance with said result of said comparing means.