Trick play for MP3
View Patent ↗Trick play and/or editing is applied to an original data stream, for example an MP3 data stream which includes headers and signal data interspersed with each other. Each header specifies a distance to a subsequent header, each header corresponding to a frame of signal data, the header being associated with a pointer that points a starting point of the signal data for that frame relative to the header. Before applying trick play, the original data stream is converted into an intermediate data stream of the same type as the original stream. During conversion, the starting points of the frames are moved to predetermined positions relative the associate headers and the headers are modified to create additional space between the headers so that the frames fit between headers.
1. A signal processing apparatus for processing data streams that comprises headers and signal data interspersed with each other, each header specifying a distance to a subsequent header, each header corresponding to a frame of signal data, the header being associated with a pointer that points to a starting point of the signal data for that frame relative to the header, the apparatus comprising
an input for receiving an original data stream;
a stream converter following the input, the stream converter converting the original data stream into an intermediate data stream, the stream converter moving the starting points of the frames to predetermined positions and modifying the headers to create additional space between the headers so that the frames fit between headers;
wherein the stream converter is arranged to modify the headers by adjusting a bit rate specified in the headers of the intermediate stream without modifying an actual bit rate of the signal data.
2. The signal processing apparatus according to claim 1 , comprising
a trick play and/or editing unit coupled to an output of the stream converter for processing the intermediate data stream.
3. The signal processing apparatus according to claim 1 , wherein said predetermined position follows the header so that no data associated with a preceding frame occurs between the header arid said predetermined position in the intermediate stream.
4. The signal processing apparatus according to claim 1 , wherein the stream converter is arranged to modify the bit rate specified in the headers of the intermediate stream to a maximum settable bit rate value.
5. The signal processing apparatus according to claim 1 , wherein the stream converter is arranged to modify the bit rate specified in the headers of the intermediate stream to signal data dependent bit rates, the respective bit rate of a respective header being modified to a minimum settable value that is higher than the actual bit rate of the frame associated with that header.
6. The signal processing apparatus according to claim 1 wherein said original data stream is an MP3 type of data stream.
7. The signal processing apparatus according to claim 1 , wherein the data streams have been incorporated in program streams, a given program stream comprising several sectors, each sector comprising a sector header and a plurality of the data frames,
wherein the apparatus further comprises means for jumping to a position several sectors forwards or backwards in the given program stream; reading the data frames from a current sector associated with that position; and furnishing the data frames of the current sector to the stream converter.
8. The signal processing apparatus according to claim 7 , wherein from the position several sectors forwards or backwards one more sector back in time is read to be able to find the main data for the first data frame of the current sector in the case this data is not present in the current sector.
9. A method of applying trick play and/or editing to signal data from an original data stream that comprises headers and signal data interspersed with each other, each header specifying a distance to a subsequent header, each header corresponding to a frame of signal data, the header being associated with a pointer that points to a starting point of the signal data for that frame relative to the header, the method comprising the acts of:
converting the original data stream into an intermediate data stream, said converting comprising moving the starting points of the frames to predetermined positions and modifying the headers to create additional space between the headers so that the frames fit between headers; and
applying trick play and/or editing to the intermediate data stream;
wherein the headers are modified by adjusting a bit rate specified in the headers of the intermediate stream without modifying an actual bit rate of the signal data.
10. The method according to claim 9 , the bit rate specified in the headers of the intermediate stream is modified to a maximum settable bit rate value.
11. The method according to claim 10 , the bit rate specified in the headers of the intermediate stream is modified to signal data dependent bit rates, the respective bit rate of a respective header being modified to a minimum settable value that is higher than the actual bit rate of the frame associated with that header.
12. The method according to claim 9 wherein said original data stream is an MP3 type of data stream.
13. The method according to claim 9 , wherein the data streams have been incorporated in program streams, a given program stream comprising several sectors, each sector comprising a sector header and a plurality of the data frames, the method further comprising the acts of:
jumping to a position several sectors forwards or backwards in the given program stream;
reading the data frames from a current sector associated with that position; and
converting the data frames in the sector to the intermediate stream.
14. The method according to claim 13 , wherein from the position several sectors forwards or backwards one more sector back in time is read to be able to find the main data for the first data frame of the current frame in the case this data is not present in the current sector.
15. An apparatus comprising:
an input for receiving a data stream;
a converter configured to move starting points of frames of said data stream to predetermined positions and to modify headers of said frames to create additional space between the headers so that the frames fit between the headers;
wherein said converter is further configured to modify the headers by adjusting a bit rate specified in the headers without modifying an actual bit rate of data included in said frames.
16. The apparatus of claim 15 , wherein said predetermined position follows a header of the headers so that no data associated with a preceding frame occurs between the header and said predetermined position.
17. The apparatus of claim 15 , wherein said data stream is an MP3 type of data stream.