Information recording device information recording method information reproduction device information reproduction method information recording program information reproduction program information recording medium and recording medium

An information-reproduction apparatus that reproduces said recorded information from said information-recording medium on which an encoded-information-recording area in which encoded information, which is obtained by encoding recording information containing at least one unit of image information while changing the encoding key at the boundary between the image-information unit and a different encoding unit;

• and a key-change-information-recording area in which key-change information, which indicates whether or not a plurality of encoding keys is necessary for encoding still-image information contained in said image-information unit in said encoded information, are recorded;
• and comprising:
• an encoded-information-detection device which detects said encoded information from said information-recording medium;
• a key-change-information-detection device which detects said key-change information from said information-recording medium;
• a decoding device which decodes said encoded information based on detected said key-change information;
• and
• a reproduction device which reproduces the decoded said encoded information.

An information-reproduction method that reproduces said recorded information from said information-recording medium on which an encoded-information-recording area in which encoded information, which is obtained by encoding recording information containing at least one unit of image information while changing the encoding key at the boundary between the image-information unit and a different encoding unit;

• and a key-change-information-recording area in which key-change information, which indicates whether or not a plurality of encoding keys is necessary for encoding still-image information contained in said image-information unit in said encoded information, are recorded;
• and comprising:
• an encoded-information-detection process of detecting said encoded information from said information-recording medium;
• a key-change-information-detection process of detecting said key-change information from said information-recording medium;
• a decoding process of decoding said encoded information based on detected said key-change information;
• and
• a reproduction process of reproducing the decoded said encoded information.

An information-reproduction program that makes a reproduction computer contained in an information-reproduction apparatus that reproduces said recorded information from said information-recording medium on which an encoded-information-recording area in which encoded information, which is obtained by encoding recording information containing at least one unit of image information while changing the encoding key at the boundary between the image-information unit and a different encoding unit;

• and a key-change-information-recording area in which key-change information, which indicates whether or not a plurality of encoding keys is necessary for encoding still-image information contained in said image-information unit in said encoded information, are recorded;
• function as:
• an encoded-information-detection device which detects said encoded information from said information-recording medium;
• a key-change-information-detection device which detects said key-change information from said information-recording medium;
• a decoding device which decodes said encoded information based on detected said key-change information;
• and
• a reproduction device which reproduces the decoded said encoded information.