Methods and apparatus for making and replaying digital video recordings, and recordings made by such methods

• US 20010026561A1
• Filed: 03/27/2001
• Published: 10/04/2001
• Est. Priority Date: 03/31/2000
• Status: Active Grant

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Kelly, Declan P., Morris, Octavius J., Van Gestel, Wilhelmus J.
• Granted Patent: US 7,313,315 B2
• Time in Patent Office: Days
• US Class Current: 370/487
• 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 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/329 on a disc [VTOC]
• CPC Class Codes: H04N 21/2389 Multiplex stream processing, e.g. multiplex stream encrypting
• CPC Class Codes: H04N 21/4147 PVR [Personal Video Recorder] H04N5/76 takes precedence ; arrangements for broadcast with accumulation-type receivers H04H20/40
• CPC Class Codes: H04N 21/42646 for reading from or writing on a non-volatile solid state storage medium, e.g. DVD, CD-ROM
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/4334 Recording operations recording of a television signal H04N5/76; arrangements for recording or accumulating broadcast information or broadcast-related information H04H60/27
• CPC Class Codes: H04N 21/4344 Remultiplexing of multiplex streams, e.g. by modifying time stamps or remapping the packet identifiers
• CPC Class Codes: H04N 21/4385 Multiplex stream processing, e.g. multiplex stream decrypting
• CPC Class Codes: H04N 21/835 Generation of protective data, e.g. certificates protecting software against unauthorised usage in a vending or licensing environment G06F21/10
• CPC Class Codes: H04N 5/775 between a recording apparatus and a television receiver
• CPC Class Codes: H04N 5/85 on discs or drums
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

Broadcast data received in MPEG Transport Stream format (TS) is processed (8) to produce a modified transport stream for recording on an optical disc (3) to record the content of a selected audio-visual program. Various techniques are disclosed for permitting random access within the recording, but without re-packetising or remultiplexing the audio and video elementary streams, for example into program stream format. The received TS (DVIN) occasionally includes stream mapping information (PAT/PMT) identifying a transport packet ID code associated with each elementary stream, said stream mapping information being subject to change throughout the received TS. The packet IDs in the modified transport stream can be re-mapped to a uniform set of values to permit random entry to the recorded stream. Alternatively, the current stream mapping information may be inserted at every potential entry point in the modified stream. Characteristic point information (CPI) defining a set of potential entry points throughout the stream is generated by parsing the received stream, and recorded in a separate file to facilitate location of entry points on the disk. Entry points may for example comprise all I-pictures, or a subset of them. Clock reference values (PCR) not carried in one of the wanted streams are inserted in the modified transport stream using a separate packet ID. The recorded stream can be passed to a standard decoder with little or no further modification.

Claims

1. A method of processing data received in a transport stream format to produce a modified transport stream for recording on a recording medium to record the content of a selected audio-visual programme (hereinafter referred to as the wanted content), the received transport stream comprising a multiplex of elementary streams conveying not only the wanted content but also the content of other programmes not to be recorded (the unwanted content), said elementary streams of data having been encoded, divided into elementary stream (ES) packets with packet headers, the ES packets further sub-divided into a plurality of smaller transport packets, and the transport packets of the first and second elementary streams interleaved in the received transport stream with each other and with transport packets carrying data from neither stream, wherein the said modified transport stream is produced by:

identifying and selecting received transport packets which correspond to the wanted content;

recording the selected transport packets within a recording medium to form said modified transport stream, so as to preserve compliance with a transport stream target decoder model substantially without re-packetising or remultiplexing the streams; and

recording auxiliary information on the same recording medium for use by a reproducing apparatus in gaining access to the content of the modified transport stream via any of a set of potential entry points throughout the wanted content.

2. A method as claimed in

claim 1

wherein said auxiliary information includes information stored in a file separately from a file holding the modified transport stream.

3. A method as claimed in

claim 2

wherein said auxiliary information comprises an index listing characteristic points within at least one of the wanted elementary streams, and is obtained by parsing the elementary stream to identify individual access units offering a valid entry point for decoding said at least one elementary stream.

4. A method as claimed in

claim 3

wherein said characteristic points are defined with a frequency substantially greater than one per second on the presentation time scale.

5. A method as claimed in

claim 3

wherein said characteristic points are defined with reference to a video elementary stream, each referring to an intra-coded picture data.

6. A method as claimed in

claim 1

wherein at least part of said auxiliary information is recorded within the modified transport stream.

7. A method as claimed in

claim 1

wherein the received transport stream occasionally includes stream mapping information identifying a transport packet ID code associated with each elementary stream, said stream mapping information being used to identify the wanted content and being subject to change throughout the received transport stream, and wherein at least part of said auxiliary information is created by parsing the received transport stream to extract the mapping information, and recorded so that current mapping information is accessible at each potential entry point without parsing the modified transport stream prior to the entry point.

8. A method as claimed in

claim 6

wherein at least part of said auxiliary information comprises additional transport packets inserted at each potential entry point in the modified transport stream.

9. A method as claimed in

claim 6

, wherein at least part of said auxiliary information overwrites header information received within the transport packets, in order to define the modified transport stream.

10. A method as claimed in

claim 9

wherein the received transport stream occasionally includes stream mapping information identifying a transport packet ID code associated with each elementary stream, said stream mapping information being used to identify the wanted content and being subject to change throughout the received transport stream, wherein said auxiliary information overwrites packet ID codes in the transport packets so as to re-map the wanted content to a uniform set of ID codes throughout the modified transport stream.

11. A method as claimed in

claim 1

, including the steps of:

identifying in the received data an elementary stream conveying auxiliary data useful in playback of the programme to be recorded; and

in the case where the elementary stream conveying the auxiliary data is one conveying part of the unwanted content, generating a new elementary stream conveying the auxiliary data without the unwanted content.

12. A method according to

claim 11

wherein the auxiliary data comprises clock reference data for synchronising playback of the elementary streams.

13. A method as claimed in

claim 1

, wherein said elementary streams comprise at least video and audio of an audio-visual programme to be recorded.

14. A method as claimed in

claim 1

, wherein said received transport stream is compliant with the MPEG transport stream specification.

15. A method as claimed in

claim 1

, further comprising:

reproducing stored programme segments with a timing different to that of the received transport stream, in accordance with user command, by reading the recorded auxiliary information and using it to enter and commence reproduction by reading said modified transport stream from a desired entry point.

16. A method as claimed in

claim 15

wherein said reproducing is performed to effect a trick play mode of a frame-based elementary stream, using the auxiliary information to step through the programme while presenting a subset of frames to a user, by reading said modified transport stream at a succession of entry points.

17. A method as claimed in

claim 15

wherein said auxiliary information is read and used implicitly as part of a standard decoding of the modified transport stream.

18. A method as claimed in

claim 15

wherein said auxiliary information is read and used to modify further the transport stream as reproduced from the recording medium, prior to standard decoding of the further modified transport stream.

19. A recording medium wherein a modified transport stream has been recorded by a method as claimed in

claim 1

.

20. A signal conveying a modified transport stream to or from a recording medium, wherein the modified transport stream has been modified by a method as claimed in

claim 1

.

21. A signal as claimed in

claim 20

wherein said modified transport stream has been reproduced from said recording medium by a method as claimed in

claim 15

.

22. An apparatus for recording a multiplex of elementary stream data received in a transport format the apparatus comprising means specifically adapted to generate and record a modified transport stream by a method as claimed in

claim 1

.

23. An apparatus as claimed in

claim 22

further comprising means for reproducing said modified transport stream by a method as claimed in

claim 15

.

33. An apparatus as claimed in

claim 32

further comprising means for reproducing said modified transport stream by a method as claimed in any of

claim 15

.

24. A method of processing a received data stream to produce a modified stream for recording on a recording medium to record the content of a selected audio-visual programme (hereinafter referred to as the wanted content), the received data stream comprising a multiplex of elementary streams conveying not only the wanted content but also the content of other programmes not to be recorded (the unwanted content), the method comprising:

identifying and extracting from the received data stream the elementary data stream(s) conveying the wanted content;

identifying in the received data an elementary stream conveying auxiliary data useful in playback of the programme to be recorded;

in the case where the elementary stream conveying the auxiliary data is one conveying part of the unwanted content, generating a new elementary stream conveying the auxiliary data without that part of the unwanted content; and

multiplexing together the elementary stream(s) extracted from the received stream with the new elementary stream to form said modified data stream for recording.

25. A method according to

claim 24

wherein the auxiliary data comprises a clock reference data for synchronising playback of the audio-visual programme.

26. A method according to

claim 24

wherein the received data stream is an MPEG-compliant Transport Stream as defined in ISO/IEC 13818-1 and the auxiliary data comprises the Program Clock Reference (PCR) as defined therein.

30. A recording medium wherein a modified transport stream has been recorded by a method as claimed in

claim 24

.

31. A signal conveying a modified transport stream to or from a recording medium, wherein the modified transport stream has been modified by a method as claimed in

claim 24

.

32. An apparatus for recording a multiplex of elementary stream data received in a transport format the apparatus comprising means specifically adapted to generate and record a modified transport stream by a method as claimed in

claim 24

.

27. A method of processing data received in a transport stream format to produce a modified transport stream for recording on a recording medium to record the content of a selected audio-visual programme (hereinafter referred to as the wanted content), said elementary streams of data having been encoded, divided into elementary stream (ES) packets with packet headers, the ES packets further sub-divided into a plurality of smaller transport packets, and the transport packets of the first and second elementary streams interleaved in the received transport stream with each other and with transport packets carrying data from neither stream, and wherein the received transport stream occasionally includes stream mapping information identifying a transport packet ID code associated with each elementary stream, said stream mapping information being subject to change throughout the received transport stream, wherein the said modified transport stream is produced by:

identifying received transport packets which correspond to the wanted content using said stream mapping information;

modifying packet ID codes in the transport packets so as to re-map the wanted content to a uniform set of ID codes according to their content type;

recording the selected transport packets within a recording medium to form said modified transport stream, thereby to preserve compliance with a transport stream target decoder model and provide a greater number of potential entry points than in the received stream.

29. A method as claimed in

claim 27

wherein at least part of said auxiliary information comprises additional transport packets inserted to reproduce current mapping information at each potential entry point in the modified transport stream.

34. A recording medium wherein a modified transport stream has been recorded by a method as claimed in

claim 27

.

35. A signal conveying a modified transport stream to or from a recording medium, wherein the modified transport stream has been modified by a method as claimed in

claim 27

.

36. An apparatus for recording a multiplex of elementary stream data received in a transport format the apparatus comprising means specifically adapted to generate and record a modified transport stream by a method as claimed in

claim 27

.

28. A method of processing data received in a transport stream format to produce a modified transport stream for recording on a recording medium to record the content of a selected audio-visual programme (hereinafter referred to as the wanted content), said elementary streams of data having been encoded, divided into elementary stream (ES) packets with packet headers, the ES packets further sub-divided into a plurality of smaller transport packets, and the transport packets of the first and second elementary streams interleaved in the received transport stream with each other and with transport packets carrying data from neither stream, and wherein the received transport stream occasionally includes stream mapping information identifying a transport packet ID code associated with each elementary stream, said stream mapping information being subject to change throughout the received transport stream, wherein the said modified transport stream is produced by:

identifying received transport packets which correspond to the wanted content using said stream mapping information;

parsing the receive transport packets to obtain said mapping information for potential entry points throughout at least on of the elementary streams;

recording the selected transport packets together with said auxiliary information within a recording medium to form said modified transport stream, thereby to preserve compliance with a transport stream target decoder model and while providing a greater number of potential entry points than in the received stream.

37. A recording medium wherein a modified transport stream has been recorded by a method as claimed in

claim 28

.

38. A signal conveying a modified transport stream to or from a recording medium, wherein the modified transport stream has been modified by a method as claimed in

claim 28

.

39. An apparatus for recording a multiplex of elementary stream data received in a transport format the apparatus comprising means specifically adapted to generate and record a modified transport stream by a method as claimed in

claim 28

.