BIT STREAM GENERATION METHOD AND BIT STREAM GENERATATION APPARATUS
A bit stream generation apparatus includes: an analysis unit which specifies, for each overlay position, an overlay position for overlaying, onto the first bit stream, respective bits of supplementary information which is a bit string, and also specifies replacement data for the replacement in accordance with the supplementary information, by analyzing a data structure of a first bit stream; a transformation table creation unit which creates a transformation table indicating the overlay position and the replacement data specified by the analysis unit; and an adding unit which generates a second bit stream by adding, to the first bit stream, the transformation table created by the transformation table creation unit.
1 . A bit stream generation method for generating a bit stream, said method comprising:
creating transformation information indicating a position for overlaying, onto a first bit stream resulting from coding of data, respective bits of supplementary information which is a bit string, the position being a position at which it is determined whether or not data is to be replaced, according to the respective bits of the supplementary information; and
generating a second bit stream by adding the generated transformation information to the first bit stream.
2 . The bit stream generation method according to claim 1 ,
wherein said creating of the transformation information includes:
specifying replacement data per position by analyzing a data structure of the first bit stream, the replacement data replacing data in accordance with the position and the supplementary information, and having a code length which does not change through the replacement; and
creating the replacement data and the information indicating the specified position, as the transformation information.
3 . The bit stream generation method according to claim 2 ,
wherein the first bit stream is variable-length coded,
said creating of the transformation information includes specifying a position, in variable-length coding, of coded data having a same run length, a different level and a same code length is specified as the position, by analyzing a data structure of the first bit stream, and
said specifying of the replacement data includes specifying, as the replacement data, coded data of a same run length, a different level and a same code length as compared with the coded data located in the specified position.
4 . The bit stream generating method according to claim 2 ,
wherein the first bit stream is variable-length coded,
said creating of the transformation information includes
specifying a position, in variable length coding, of coded data having a same level, a different run length and a same code length, as the position by analyzing the data structure of the first bit stream, and
said specifying of the replacement data includes
specifying, as the replacement data, coded data having a same level, a different run length and a same code length as compared with the coded data located in the specified position.
5 . The bit stream generation method according to claim 1 ,
wherein said generating of the second bit stream includes:
changing a stuff bit to a longer stuff bit, the stuff bit being added to a predetermined unit including the position so that the predetermined unit reaches a pre-set code length; and
generating the second bit stream by adding the changed first bit stream to the transformation information.
6 . The bit stream generation method according to claim 1 ,
wherein said creating of the transformation information includes
specifying, as the position, a predetermined unit which includes a stuff bit of a predetermined threshold or greater, by analyzing a data structure of the first bit stream, the stuff data being added so that the predetermined unit reaches a pre-set code length, and
said generating of the second bit stream includes
creating information indicating the specified position, as the transformation information.
7 . A bit stream generation apparatus which generates a bit stream, said apparatus comprising:
a transformation information creation unit operable to create transformation information indicating a position which is a position for overlaying, onto a first bit stream resulting from coding of data, respective bits of supplementary information that is a bit string, the position being a position at which it is determined whether or not data is to be replaced, according to the respective bits of the supplementary information; and
an adding unit operable to generate a second bit stream by adding, to the first bit stream, the transformation information is created by said transformation information creation unit.
8 . A program for generating a bit stream, the program causing a computer to execute:
creating transformation information indicating a position for overlaying, onto a first bit stream resulting from coding of data, respective bits of supplementary information which is a bit string, the position being a position at which it is determined whether or not data is to be replaced, according to the respective bits of the supplementary information; and
generating a second bit stream by adding, to the first bit stream, the transformation information created by said transformation information creation unit.
9 . A storage medium in which a bit stream is stored,
wherein transformation information indicating a position is further stored, the position being a position for overlaying, onto a first bit stream resulting from coding of data, respective bits of supplementary information which is a bit string, and being a position at which it is determined whether or not data is to be replaced, according to the respective bits of the supplementary information.