Method and apparatus for storage or relocation of defined positions in a data stream

• US 20050122974A1
• Filed: 11/15/2004
• Published: 06/09/2005
• Est. Priority Date: 11/25/2003
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Hubler, Friedemann
• Granted Patent: US 7,664,105 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 27/005 Reproducing at a different information rate from the information rate of recording for television signals H04N5/783
• CPC Class Codes: G11B 27/329 on a disc [VTOC]

Abstract

In packet-oriented data streams, structural information which is needed, for example, for searching or for forwarding or reversing is contained only in specific packets. According to the invention, while a data stream is being stored, an information file is produced which contains references to the starts of all those packets which contain this information. The information file contains data blocks, and each data block identifies the position of a data packet with structural information, as well as the distance to the next or previous such data packet, and additional information relating to the respective data packet.

Claims

1. A method for storage or relocation of defined positions in a data stream of a first type comprising first data packets of a constant size, wherein the data items contained in the first data packets can be combined without changing their sequence to form second or further data packets which may have a variable size and which result in one or more different data streams of a second type or further types, wherein

the first data packets, which are located at the defined positions, contain the starts or headers of the second data packets;

and

the description of the defined positions as well as additional information which relates to the respective second data packet is stored or retrievable separately from the data streams.

2. The method as claimed in claim 1, wherein the first data packets which are located at the defined positions automatically contain the starts or headers of all of the second data packets which are associated with the same data stream.

3. The method as claimed in claim 1, wherein the second data packets contain only data of one type, with this data being encoded, and wherein the starts or headers of the second data packets are the entry points for decoding of the second data stream.

4. The method as claimed in claim 1, with the position of a data packet in the data stream of the first type, which contains the start or header of a data packet of the data stream of the second type, being described relative to another data packet in the data stream of the first type, which contains the start or header of the next or previous second data packet in the data stream of the second type.

5. The method as claimed in claim 4, with the relevant indication being stated as the number of packets of the first type and as the number of bytes.

6. The method as claimed in claim 1, with the separately stored information containing the position of headers of PES packets as well as the timestamp of the respective header, and with the data stream of the first type being an MPEG-2 transport data stream.

7. A method for forwarding or reversing within a data stream of the second type, which comprises variable size data packets being extracted from other data packets of constant size in a data stream of the first type, and with a file pointer indicating a current position within the data stream of the first type, wherein

the relative position of those data packets in the first type data stream which contain the starts or headers of the data packets in the second type data stream are retrieved from a memory or from a file;

the position within the first type data stream (MTS) of another data packet is calculated from the position of the file pointer and from the retrieved position of the other data packet; and

the file pointer jumps to the calculated position within the data stream of the first type.

8. The method as claimed in claim 7, with the position of all those data packets in the data stream of the first type which contain the starts or headers of the data packets in the data stream of the second type being called from a memory or from a file.

9. The method as claimed in claim 7, with the data packets in the data stream of the second type containing a timestamp in the header, wherein this timestamp is also stored in the memory or in the file together with the position details for the data packet, which contains the respective header, in the data stream of the first type, and is called up from this memory or this file, and this timestamp is used for determination or indication of the position within the data stream of the second type.

10. An apparatus for forwarding or reversing within a data stream of a second type, which comprises data packets of variable size, with these data packets being extracted from other data packets of constant size in a data stream of the first type, and with a file pointer indicating a current position within the data stream of the first type, wherein the apparatus contains the following components:

a memory medium from which the position of those data packets in the data stream of the first type which contain the starts or headers of the data packets in the data stream of the second type is retrieved;

a means for calculation of the position of another data packet within the data stream of the first type from the current position of the file pointer and from the position details for the other data packet, as called up from the memory medium; and

a means for setting the file pointer to the calculated position within the data stream of the first type.

11. The apparatus as claimed in claim 10, with the data packets in the data stream of the second type containing time markers which can also be determined from additional information which is retrieved from the memory medium together with the position details of the data packets containing the respective packet header, and with the other data packet which is selected for forwarding or reversing being chosen such that its associated time marker and the time marker contained in the current data packet have a predetermined time difference between them.

12. An apparatus for calculation and storage of information which relates to a data stream of a second type comprising data packets of variable size, with these data packets containing time markers in their headers and being composed of the content from other data packets of constant size of a data stream of a first type, wherein the apparatus contains:

means for associating the data packets of the data stream of the first type to a data stream of the second type;

means for extraction of the time markers of the data packets of the second type data stream from the data packets of the first type data stream;

a counter for counting the data packets of the first type data stream from the current data packet which contains a header to the next data packet which contains a header and is part of the same second type data stream;

means for storing data blocks, with each data block being associated with one data packet of the second type data stream and containing at least the determined number of packets and the extracted time marker.