File and content management

1. A table comprising:

at least one record mapping a respective data offset in a file containing a representation of a bitstream to a corresponding time offset in the bitstream,

wherein the at least one record stored on a storage medium in the table is used to search and retrieve data from the bitstream,

wherein at least one record in the table is mapped to at least one further record, wherein the at least one further record comprises conditional access information used to decode a desired portion of data in the bitstream upon location of the desired portion of data using the table and at least one television control command used to control access to at least one audio visual program included in the bitstream, and wherein the bitstream and the conditional access information are synchronized at the time of storing the conditional access information and the bitstream, and

wherein the bitstream comprises:

at least one key frame used to regenerate a portion of audiovisual data independently of other portions of bitstream data, and

at least one delta frame configured to map changes from the portion of audiovisual data represented by the key frame to the bitstream data.

2. A table according to claim 1 , wherein the bitstream is a variable bitrate bitstream.

3. A table according to claim 1 , wherein the table comprises at least three records, and the time offsets are periodic.

4. A table according to claim 3 , wherein the period of the time offsets is varied.

5. A table according to claim 3 , wherein the period of the time offsets is chosen to match a characteristic of the bitstream, and is one selected from the group consisting of 0.5, 1, 2, and 10 seconds.

6. A table according to claim 1 , wherein the bitstream comprises MPEG data, and the at least one portion of bitstream data comprises an intra-frame.

7. A table according to claim 1 , wherein the table is generated automatically during recordal of the representation of the bitstream in the file.

8. A table according to claim 1 , wherein the said at least one further record is stored in a further table.

9. A table according to claim 8 , wherein the said at least one further record is inserted upon command of a user.

10. A table according to claim 1 , wherein the said at least one record in the table is mapped to the respective at least one further record upon command of a user.

11. A table according to claim 1 , wherein the file is encoded and the at least one record maps a data offset in the encoded file to a corresponding time offset in the bitstream.

12. A table according to claim 1 , wherein records are inserted in dependence upon characteristics of the bitstream.

13. A table according to claim 1 , wherein at least one record is inserted upon command of a user.

14. A table according to claim 1 , wherein at least one record is inserted automatically.

15. A table according to claim 1 , adapted for storage in a file with the representation of the bitstream.

16. A table according to claim 1 , wherein a period of the corresponding time offset is chosen based on a size of a cryptoperiod.

17. A method of facilitating the searching of a file containing a representation of a bitstream, comprising:

generating a table comprising at least one record mapping a respective data offset in a file containing a representation of a bitstream to a corresponding time offset in the bitstream;

wherein the at least one record is used to search and retrieve data from the bitstream,

locating a desired portion of data in the representation of the bitstream using the table, wherein at least one record in the table is mapped to a respective at least one further record, and the said at least one further record comprises conditional access information and at least one television control command used to control access to at least one audio visual program included in the bitstream, and wherein the bitstream and the conditional access information are synchronized at the time of storing the conditional access information and the bitstream; and

decoding the desired portion of data in the representation of the bitstream using the conditional access information from the at least one further record,

wherein the bitstream comprises:

at least one key frame used to regenerate a portion of audiovisual data independently of other portions of bitstream data, and

at least one delta frame configured to map changes from the portion of audiovisual data represented by the key frame to the bitstream data.

18. A method according to claim 17 , wherein the bitstream is a variable bitrate bitstream.

19. A method according to claim 17 , wherein the table comprises at least three records, and the time offsets are periodic.

20. A method according to claim 19 , wherein the period of the time offsets is chosen to match a characteristic of the bitstream, and is one selected from the group consisting of 0.5, 1, 2, or 10 seconds.

21. A method according to claim 17 , wherein:

the time offset of the at least one record corresponds to the respective at least one portion of a bitstream data.

22. A method according to claim 17 , wherein the bitstream comprises MPEG data, and the at least one portion of bitstream data comprises an intra-frame.

23. A method according to claim 17 , wherein the table is generated automatically during recordal of the representation of the bitstream in the file.

24. A method according to claim 17 , wherein the said at least one further record is stored in a further table.

25. A method according to claim 24 , wherein the said at least one further record is inserted upon command of a user.

26. A method according to claim 17 , wherein the at least one record in the table is mapped to the respective at least one further record upon command of a user.

27. A method according to claim 17 , wherein the file is encoded and the at least one record maps a data offset in the encoded file to a corresponding time offset in the bitstream.

28. A method according to claim 17 , wherein at least one record is inserted in dependence upon characteristics of the bitstream.

29. A method according to claim 17 , wherein at least one record is inserted upon the command of a user.

30. A method according to claim 17 , wherein at least one record is inserted automatically.

31. A method according to claim 17 , further comprising storing the table in a file containing the representation of the bitstream.

32. A method according to claim 17 , wherein a period of the corresponding time offset is chosen based on a size of a cryptoperiod.