File generating method and file generating apparatus
A file generating method according to one aspect of the present disclosure is a file generating method for generating an MP4 file, the file generating method including: step S 11 of acquiring an original file made in a file format different from MP4; step S 12 of acquiring a difference file including data that is not included in the original file; step S 13 of acquiring a procedure file indicating a procedure for generating the MP4 file; and step S 14 of generating the MP4 file by combining the data included in the difference file and data included in the original file in accordance with the procedure indicated in the procedure file.
1. A file generating method for generating an MP4 file, the file generating method comprising:
acquiring an original file made in a file format different from MP4;
acquiring a difference file including data that is not included in the original file;
acquiring a procedure file indicating a procedure for generating the MP4 file; and
generating the MP4 file by combining the data included in the difference file with data included in the original file in accordance with the procedure indicated in the procedure file, wherein
in acquisition of the original file, the original file in plain text is acquired, and
in generation of the MP4 file,
every time a section that constitutes the original file is acquired, a portion of the MP4 file corresponding to the section is generated and encrypted, and
every time the portion that constitutes the MP4 file is encrypted, the section of the original file corresponding to the portion is deleted.
2. The file generating method according to claim 1 , wherein in acquisition of the original file, the original file made in a file format of MPEG2-TS is acquired.
3. The file generating method according to claim 1 , wherein in acquisition of the original file, the difference file, and the procedure file, acquisition is performed through reading of the original file, the difference file, and the procedure file from an optical disc.
4. The file generating method according to claim 1 , wherein
the procedure file describes ranges of a plurality of respective sections included in the difference file, and ranges of a plurality of respective sections included in the original file, so that the ranges of the sections included in the difference file and the ranges of the sections included in the original file are arranged alternately, and
in generation of the MP4 file, the MP4 file is generated through combination of the sections indicated by the respective ranges in order of the respective ranges described in the procedure file.
5. The file generating method according to claim 4 , wherein
the ranges of the plurality of respective sections included in the difference file are described in the procedure file in data size, and
the ranges of the plurality of respective sections included in the original file are described in the procedure file in starting position and data size of the sections.
6. The file generating method according to claim 1 , wherein
the data size of the MP4 file is described in the procedure file, and
the file generating method further comprises determining whether a medium has free space for recording the MP4 file based on the data size of the MP4 file described in the procedure file.
7. The file generating method according to claim 1 , wherein
an attribute of the MP4 file is described in the procedure file, and
the file generating method further comprises reading the attribute described in the procedure file.
8. The file generating method according to claim 1 , wherein
a buffer size required for playback of the MP4 file is described in the procedure file, and
the file generating method further comprises reading the buffer size described in the procedure file.
9. The file generating method according to claim 1 , wherein
a first file name, which is a name of the original file, and a second file name, which is a name of the difference file, are described in the procedure file, and
the file generating method further comprises specifying a file with the first file name described in the procedure file as the original file, and specifying a file with the second file name described in the procedure file as the difference file.
10. The file generating method according to claim 1 , wherein in generation of the MP4 file, MP4-conforming header information that is data included in the difference file is combined with data included in the original file.
11. A file generating apparatus for generating an MP4 file, the file generating apparatus comprising:
an original file acquisition unit that acquires an original file made in a file format different from MP4;
a difference file acquisition unit that acquires a difference file including data that is not included in the original file;
a procedure file acquisition unit that acquires a procedure file indicating a procedure for generating the MP4 file; and
a generation unit that generates the MP4 file by combining the data included in the difference file with data included in the original file in accordance with the procedure indicated in the procedure file, wherein
in acquisition of the original file, the original file in plain text is acquired, and
in generation of the MP4 file,
every time a section that constitutes the original file is acquired, a portion of the MP4 file corresponding to the section is generated and encrypted, and
every time the portion that constitutes the MP4 file is encrypted, the section of the original file corresponding to the portion is deleted.