EP1634290A1 - Flux video brouilles dans un produit audiovisuel - Google Patents

Flux video brouilles dans un produit audiovisuel

Info

Publication number
EP1634290A1
EP1634290A1 EP04736214A EP04736214A EP1634290A1 EP 1634290 A1 EP1634290 A1 EP 1634290A1 EP 04736214 A EP04736214 A EP 04736214A EP 04736214 A EP04736214 A EP 04736214A EP 1634290 A1 EP1634290 A1 EP 1634290A1
Authority
EP
European Patent Office
Prior art keywords
video
sequence
cells
video stream
audiovisual
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04736214A
Other languages
German (de)
English (en)
Inventor
Stuart ZooTech Limited GREEN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zootech Ltd
Original Assignee
Zootech Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB0312874.1A external-priority patent/GB0312874D0/en
Application filed by Zootech Ltd filed Critical Zootech Ltd
Publication of EP1634290A1 publication Critical patent/EP1634290A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0092—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which are linked to media defects or read/write errors
    • G11B20/00927—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which are linked to media defects or read/write errors wherein said defects or errors are generated on purpose, e.g. intended scratches
    • G11B20/00942—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which are linked to media defects or read/write errors wherein said defects or errors are generated on purpose, e.g. intended scratches said intentional errors occurring due to an invalid playback path or program chain
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/00137—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which result in a restriction to contents recorded on or reproduced from a record carrier to authorised users
    • G11B20/00152—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which result in a restriction to contents recorded on or reproduced from a record carrier to authorised users involving a password
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/00166—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0092—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which are linked to media defects or read/write errors
    • G11B20/00927—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which are linked to media defects or read/write errors wherein said defects or errors are generated on purpose, e.g. intended scratches
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
    • G11B27/031—Electronic editing of digitised analogue information signals, e.g. audio or video signals
    • G11B27/034—Electronic editing of digitised analogue information signals, e.g. audio or video signals on discs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/102—Programmed access in sequence to addressed parts of tracks of operating record carriers
    • G11B27/105—Programmed access in sequence to addressed parts of tracks of operating record carriers of operating discs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/34—Indicating arrangements 
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/79—Processing of colour television signals in connection with recording
    • H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N9/82—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only
    • H04N9/8205—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only involving the multiplexing of an additional signal and the colour video signal
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/21—Disc-shaped record carriers characterised in that the disc is of read-only, rewritable, or recordable type
    • G11B2220/213—Read-only discs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
    • G11B2220/2537—Optical discs
    • G11B2220/2562—DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/84—Television signal recording using optical recording
    • H04N5/85—Television signal recording using optical recording on discs or drums
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/79—Processing of colour television signals in connection with recording
    • H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N9/804—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving pulse code modulation of the colour picture signal components
    • H04N9/8042—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving pulse code modulation of the colour picture signal components involving data reduction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/79—Processing of colour television signals in connection with recording
    • H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N9/804—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving pulse code modulation of the colour picture signal components
    • H04N9/8042—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving pulse code modulation of the colour picture signal components involving data reduction
    • H04N9/8047—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving pulse code modulation of the colour picture signal components involving data reduction using transform coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/79—Processing of colour television signals in connection with recording
    • H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N9/82—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only
    • H04N9/8205—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only involving the multiplexing of an additional signal and the colour video signal
    • H04N9/8227—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only involving the multiplexing of an additional signal and the colour video signal the additional signal being at least another television signal

Definitions

  • the present invention relates in general to a method and apparatus for use in creating or reproducing an audiovisual product.
  • the present invention relates to a method and apparatus for use in controlling access to an audiovisual product, through the use of scrambled video streams.
  • audiovisual content such as a movie or other presentation is formed by gathering together many small sections or clips of raw audio and visual content. This is usually termed an "authoring" process wherein the raw sound clips and video clips are progressively assembled and edited together to form the finished audiovisual product.
  • the audiovisual product is then recorded on some form of recording media.
  • this would be an analogue medium such as celluloid film or analogue video tape (e.g. VHS format video tape).
  • VHS format video tape e.g. VHS format video tape
  • random access media including in particular optical disk media such as DVDs, or other forms of random storage such as magnetic hard drives.
  • DVD digital versatile disc
  • DVD-Video is particularly intended for use with pre-recorded video content, such as a motion picture.
  • DVD-Video disc is played using a dedicated playback device with relatively simple user controls, and DVD players for playing DVD-Video discs are becoming relatively widespread. More detailed background information concerning the DVD-Video specification is available from DVD Forum at www . dvdforum. org, and elsewhere .
  • the DVD-Video specification contains a number of built-in copy-protection features that aim to protect the audiovisual data content of the disc. These include Content Scrambling System (CSS) , used to encrypt blocks of audio-video data to prevent such data being played separately from the DVD-Video presentation; and Macrovision Copy Protection, used to prevent video being copied using recording devices. Both of these systems are interpreted by the DVD-Video player that performs the appropriate function during playback. While these approaches are effective in protecting data content for average consumers, "reverse engineers" who are skilled and motivated to create copies of discs or parts of discs now easily defeat both systems.
  • CSS Content Scrambling System
  • Macrovision Copy Protection used to prevent video being copied using recording devices.
  • DVD-Video discs sometimes contain so-called "Easter Eggs" which are hidden data on a disc that are accessed such as by inputting a particular key combination (e.g. press a "left arrow” key within 5 seconds of a certain menu appearing) .
  • a reverse engineer can easily access such content without knowing the key combination, simply by extracting the relevant audio-video objects directly from the disc.
  • DVD-Video interrogation software packages available that can be used to rip' each of the individual video presentations on a disc. See, for example, www . dvd-ripper . com, amongst many others.
  • US 6,161,179 discloses a key- based protection method for light-readable discs, wherein a disk player provides a unique key each time a disk is played. The user communicates the unique key to a transaction service, and receives an unlock key in return. The user communicates the unlock key to the disk player. The disk player then confirms that the unlock key and the unique key have a predetermined relationship, before playing the disk.
  • This known protection method allows pay- per-view or other pay-per-use commercialisations of an audiovisual product distributed on a light-readable disk, such as in a DVD-Video format.
  • There are a wide range of applications where a greater level of security and protection is required over and above that afforded by the known copy-protection approaches. These problems arise not only in relation to DVD-Video format optical disks but occur in many other environments, especially where audiovisual content is recorded onto a random access storage medium.
  • An aim of at least some embodiments of the present invention is to provide a method and apparatus for use in creating or reproducing an audiovisual product, by which even a skilled reverse engineer is faced with substantial obstacles that inhibit free and unfettered access to the audiovisual product.
  • an audiovisual product appropriate to the present invention has plurality of cells of audiovisual data, whose playback is controlled by one or more sequence instructions.
  • each of the cells and each of the sequence instructions have a predetermined structure location within the audiovisual product, which enables navigational movements within the audiovisual product, such as from cell to cell and from one sequence instruction to another.
  • One aspect of the present invention relates to the use of an access code to control access to an audiovisual product, as a form of unlocking process.
  • a method for use in creating an audiovisual product comprising the steps of: receiving , original audiovisual data intended for playback according to an original content sequence; dividing the original audiovisual data into a plurality of cells; creating a plurality of sequence instructions each representing a playback sequence for playing back the cells in a specified order; allocating the plurality of sequence instructions each to one of a plurality of structural locations within the audiovisual product; and producing a destination function operable, based on an access code, to calculate a destination structural location amongst the plurality of structural locations and thereby select one amongst the plurality of sequence instructions.
  • a method for use in reproducing an audiovisual product comprising the steps of: receiving an access code; calculating a destination structure location within the audiovisual product by applying a destination function to the access code; and jumping to the calculated destination structure location to thereby select a sequence instruction corresponding to that location.
  • a destination structure location within the audiovisual product is calculated by applying a destination function to a received access code. Jumping to the calculated destination structure location selects a sequence instruction corresponding to that location. The selected sequence instruction consequently initiates reproduction of a sequence of the cells of audiovisual data in the audiovisual product.
  • the destination function applied to the access code is a mathematical function that returns a numerical value of the destination location dependent upon the received access code.
  • the access code may take any suitable form but preferably comprises a numerical value within a predetermined range, such that the destination function when applied to the numerical value of the access code calculates the structure location of the correct sequence instruction and so reveals protected original audiovisual data such as an "Easter egg" feature or a section of a movie.
  • the destination function is applied to an incorrect numerical value, some other structure location is derived.
  • the destination function leads to a structure location which causes a message to be displayed such as "Access Denied", or leads to an incorrect sequence instruction which results in unsatisfactory playback of the original audiovisual data.
  • the present invention provides a method for use in creating an audiovisual product, comprising the steps of: receiving original audiovisual data intended for playback according to an original content sequence; dividing the original audiovisual data into a plurality of cells; and creating a plurality of sequence instructions each representing a playback sequence for playing back the cells in a specified order, including: at least one correct sequence instruction where the playback sequence reproduces the original content sequence; and a plurality of incorrect sequence instructions where the playback sequence does not reproduce the original content sequence.
  • the present invention provides a method for use in reproducing an audiovisual product, comprising the steps of: receiving the audiovisual product, wherein a plurality of sequence instructions include at least one correct sequence instruction for reproducing the audiovisual product according to an original playback sequence, and a plurality of incorrect sequence instructions which do not reproduce the audiovisual product according to the original playback sequence; selecting one amongst the plurality of sequence instructions; and reproducing the audiovisual data in the cells according to the selected sequence instruction.
  • This aspect of the present invention provides a simple but effective mechanism for controlling access to the original audiovisual data presented in the audiovisual product.
  • Original content is divided into cells, which are to be played back in an order according to a playback sequence instruction.
  • One or more correct sequence instructions which allow an original content sequence to be reconstructed from the cells, are themselves hidden amongst a plurality of incorrect sequence instructions.
  • a relatively large number of sequence instructions are created, where only relatively few (e.g. one or two) properly play back the cells to reconstruct the original content sequence.
  • the remaining large number of incorrect sequence instructions each result in an unsatisfactory playback of the audiovisual data from the cells.
  • Such obfuscation of the correct sequence instructions leads to secure and reliable control of access to the original audiovisual data. Only a user who is able select the correct sequence instruction will be able to reveal the original audiovisual data.
  • the plurality of sequence instructions are formed as multiple permuted sequences, where only one such sequence corresponds to the original content sequence.
  • Each of the other multiple permuted sequences reproduces the audiovisual data in the cells, but not according to the original content sequence.
  • the sequence instructions each closely resemble one another and it is relatively difficult for a reverse engineer to determine which one is correct.
  • the correct sequence instruction is obfuscated amongst the multiple permuted incorrect sequence instructions .
  • the cells are arranged other than according to the original content sequence. That is, the cells are rearranged to provide a new, jumbled, sequence of cells that obscures the original audiovisual data. Recording the cells in the jumbled sequence means that a reverse engineer cannot easily recreate the original audiovisual data from the cells. Knowledge of a correct sequence instruction is also required, in order to correctly reproduce the original content sequence.
  • the present invention provides a method for use in reproducing an audiovisual product, comprising the steps of: receiving an audiovisual product having audiovisual data divided into a plurality of cells, including at least one correct cell containing correct audiovisual data proper to an original content sequence, and at least one erroneous cell containing erroneous audiovisual data, and at least one sequence instruction representing a playback sequence for playing back selected ones of the plurality of cells in a specified order; and reproducing the audiovisual data in the cells according to the sequence instruction.
  • the present invention is suitably performed on a computing platform, ideally a general purpose computing platform such as a personal computer, or a client-server computing network.
  • the present is implemented, wholly or at least in part, by dedicated hardware.
  • the present invention is performed in a home entertainment appliance such as an optical disk player or recorder.
  • the present invention is performed in a DVD-Video player for playback of DVD- Video format optical discs and/or in a DVD-recorder for recording DVD-Video format data onto an optical disc.
  • Figure 7 is a schematic view of an example original audiovisual clip
  • Figure 8 shows the identification of scene cuts within the audiovisual clip
  • Figure 9 shows the audiovisual clip subdivided into scenes
  • Figure 10 shows the audiovisual clip divided into cells
  • Figure 11 shows red herring cells inserted into the cells
  • Figure 12 shows the cells being jumbled
  • Figure 13 shows reallocation of references to the cells
  • Figure 14 shows an example correct playback sequence instruction
  • Figure 15 shows a navigational Program of a correct playback sequence instruction
  • Figure 16 shows a navigational Program of an incorrect playback sequence instruction
  • Figure 17 shows a correct playback sequence instruction amongst many incorrect playback sequence instruction
  • Figure 18 is a schematic overview of a preferred content scrambling method using video streams
  • Figure 20 is a schematic view of video objects employed in the preferred content scrambling method
  • Figure 21 is a table of an example sequence generator function
  • Figure 22 is an example of DVD virtual commands used to perform video stream switching.
  • DVD-Video format optical disk containing audiovisual content optical disk containing audiovisual content.
  • the invention is applicable to a wide variety of other environments, particularly where audiovisual content is stored in some form of random access storage media.
  • DVD-Video format will itself be superseded over time and replaced with new format definitions. That is, the present invention is likely to be applicable even in some future and as yet unrealised environments .
  • raw audio and video data are received, such as through a camera 10 and a microphone 20, or are provided from other sources such as a file storage device 25, or are created within the authoring apparatus such as by image and sound creation software.
  • the raw content data may include video clips, audio clips, still picture images, icons, button images and other visual content to be presented onscreen.
  • the content is suitably in the form of MPEG or JPEG encoded files, but may take any suitable format .
  • This original audiovisual data can take any form such as a movie, or a company presentation, or a quiz game, amongst many other possibilities.
  • the personal computer 30 acting as the authoring apparatus creates the desired audiovisual product as will be discussed in more detail below.
  • the authoring apparatus 30 writes the audiovisual product 400 onto a storage medium such as a hard disk drive within the personal computer 30 or onto an optical disk 40.
  • Figure 2 is a general overview of an apparatus for reproducing the audiovisual product 400, as may be employed in preferred embodiments of the present invention.
  • the audiovisual product 400 on the optical disk 40 is received into a playback apparatus, in this case including a DVD player 50 and television screen 60.
  • User controls are provided such as through a remote control handset 70.
  • the present invention implements multiple variations on the way in which those cells 420 are played, but without duplicating the audio-video data.
  • a PGC can contain up to 256 cells, and a Video Title Set (VTS) , which is the enclosing structure for PGCs, may contain up to 32767 PGCs. Thus, a cell may be shared by at most 32767 PGCs.
  • VTS Video Title Set
  • the audiovisual product is then formatted and recorded onto a suitable storage medium in step 540.
  • the audiovisual product is formatted according to the DVD video specification and recorded onto a hard disk drive or preferably an optical disk.
  • This step 540 may, if necessary, include downstream processing steps such as specific allocation of structure locations to the cells 410 and the sequence instructions 420, and creating an explicit disk image (i.e. a bitstream image) ready to be recorded or burnt onto an optical disk.
  • Figure ⁇ is a schematic overview of a preferred method for reproducing the audiovisual product 400.
  • Step 630 comprises playing the audiovisual data in the cells 420 according to the selected playback sequence instruction 410.
  • Step 630 suitably includes retrieving the audiovisual data in the referenced cells 420 from a storage medium such as an optical disk, performing appropriate decoding, and rendering the decoded data for output such as through a display screen and through audio speakers, as outlined above with reference to Figure 2.
  • Figure 7 shows an example audio-video film clip 700.
  • the source video content that is required to be protected consists of a 60 second clip within which there are three cuts' such that the clip contains four distinct scenes. Note that the scene cut points are typically implicit within the clip, rather than being presented as four separate sub-clips.
  • sequence will be divided into cells 420 with an average duration of 3 seconds each, resulting in a total of 20 cells to represent the sequence .
  • red herring' cells 421 that are not referenced in the correct playback sequence 410a.
  • red herring' is literally a distraction to divert attention, and derives from the use of fish to distract hunting dogs from a scent trail
  • Such erroneous cells 421 are suitably designed so that they appear very similar to correct cells 420, such that it is not possible to easily exclude all sequence instructions 410 that contain clearly incongruous cells 421. For example, suppose that the product includes a series of cells 420 of four seconds duration each, as follows :
  • some example erroneous cells are:
  • each cell is varied so as not to create a pattern from which, for example, interrogation of time codes could be used to discard obviously erroneous cells.
  • a number of erroneous ⁇ red herring' cells 421 are created, which have a similar length to the other cells 420.
  • the level of protection will increase with the number of erroneous red herring cells 421, and will typically be constrained by the space available on the disc. In this example, 20% erroneous red herring cells are assumed.
  • These erroneous red herring cells 421 ideally start and finish at points that are not shared by other valid cells, or at the point of scene cuts.
  • the erroneous cells 421 are illustrated as shaded boxes in Figure 10.
  • the erroneous red herring cells 421 are inserted into the play order of the valid cells 420, sorted by start time of the cell, as shown in Figure 11.
  • the cells 420 are jumbled by changing the location of each cell relative to others, and so determine the order in which the cells 420 will be presented on the disc.
  • the cells 420 may be jumbled arbitrarily, it will provide a higher level of protection if each possible playback sequence meets the constraints detailed in the DVD-Video specification that relate to seamless play. That is, for two cells 420 to play back seamlessly
  • cells 420 may be many sectors apart and still play back seamlessly, so in this example the cells 420 may be sequenced arbitrarily, but for illustrative purposes we assume that any cell must be within three cells 420 of its correct position.
  • the cells 420 are numbered from 1 in the order they appear on the disc. Hence, the jumbled cells 420 are renamed sequentially in the order they will appear on the disc as shown in Figure 13, using an underscore to denote renamed cell identifiers .
  • the audiovisual product is then ready to be recorded onto a suitable storage medium, in this case an optical disk.
  • a suitable storage medium in this case an optical disk.
  • further intermediate authoring steps may be performed in order to convert the authored audiovisual product into a specific version, i.e. into a disk image ready for burning onto a blank previously unrecorded optical disk.
  • the method outlined above can be extended to employ multiple VTSs and therefore increase the number of destinations that must be interrogated in order to find the correct playback sequence.
  • the video program would be divided into v sections of similar duration, with section 1 mapping to VTS 1 up to section v mapping to VTS v.
  • PGCs can be used to obfuscate the program; the correct PGC in each VTS is unrelated and is arrived at through independent calculation .
  • Playback of the audiovisual product involves determining the correct playback sequence instruction amongst the many incorrect playback sequence instructions 410.
  • various options are available to determine whether a user is authorised to access the audiovisual content. For example, a physical token such as a smart card is presented to a card reader, or some form of biometric authentication (e.g. fingerprinting) is performed.
  • the playback apparatus is then instructed to operate according to the correct playback sequence instruction, suitably by jumping to a structure location associated with the correct playback sequence instruction.
  • VOB Video Object
  • PLCs Programs and Program Chains
  • FIG 18 is an overview of a preferred method for scrambling content in an audiovisual product, using video streams.
  • Original audiovisual data is received at step 1810, such as MPEG encoded audio and/or video data.
  • the original audiovisual data 401 is divided into cells 420 in step 1820.
  • the cells 420 are distributed amongst a plurality of video streams, in step 1830. That is, instead of the cells all remaining within a single video stream, the cells are instead distributed within at least two different video streams.
  • at least one video stream switch instruction is created, in order to automatically switch from a first video stream to a second video stream during playback of the audiovisual product.
  • Step 1830 comprises creating sequence instructions 410 which control a playback sequence of the cells 420.
  • the audiovisual product is then formatted and recorded onto a suitable storage medium in step 1840.
  • original audiovisual data 401 having an intended playback sequence is divided into a plurality of cells 420, similar to the discussion above with reference to Figures 7, 8 and 9.
  • an intended playback sequence e.g. a generally linear storyline
  • the cells are divided amongst different video streams. That is, some of the cells (A, B, & D) are allocated to a first video stream 1901, whilst at least one cell (C) is allocated to a different second video stream 1902.
  • a video stream switch is required between the first stream 1901 and the second stream 1902. Simply continuing with the first stream 1901 does not result in the desired playback sequence.
  • the cell C is provided in both video streams 1901 and 1902 as cell Cl and cell C2. This makes copying more difficult, since both streams 1901 and 1902 contain apparently valid data.
  • the cell C2 is preferably an erroneous "red herring" cell containing distorted or otherwise unsatisfactory video data. Reproducing cell C2 (i.e. continuing with the first video stream 1901) does not provide satisfactory reproduction of the original audiovisual data 401. Up to nine alternative video streams may be provided within each multi-angle block, including the correct cell Cl.
  • the video stream switch instructions 2011, 2021 are performed using forced activate button commands associated with hidden menu buttons in a video object 2010 which precedes one of the multi-angle blocks 2020.
  • the VOB for cell B includes a switch command 2011 to set the SPRM3 special parameter to "2".
  • the set value of the special parameter SPRM3 determines that stream "2" is to be reproduced, in this case leading to cell Cl.
  • the VOB 2020 for cell C likewise sets SPRM3 to a value of "1" ready for a following cell.
  • the preferred embodiment uses a sequence generator to determine the correct video stream playback sequence.
  • One appropriate sequence generator is based on a deterministic algorithm that is seeded by one or more initial parameters, and from which successive values are produced by applying the generator to the set of parameters.
  • LCG Linear Congruential Generator
  • the original audiovisual data will only play back correctly if the original cell is played for each of the multi-angle blocks, for which it is necessary to know the values of the parameters to the sequence generator (A, B and M in this example) . Since there are many possible values for these parameters, one or more of the parameters can be used as a ⁇ key' to unlock the content. If incorrect parameters are chosen for playback, then incorrect video sequences will play during the multi-angle blocks, which will render the content unplayable (i.e. highly unsatisfactory) .
  • Figure 22 shows example DVD-Video navigation instructions to perform the iterations of the LCG algorithm described.
  • DVD-Video specification only a single command can be associated with a menu button. Therefore to perform the necessary sequence of instructions in each iteration of the sequence generator, it is preferred to employ forced activate buttons in a number of successive cells, prior to encountering a multi-angle block. That is, the program is in practice executed using instructions performed at the end of each of several preliminary VOBs in sequence, interleaved between each multi-angle block. Following this sequence, the Special Parameter SPRM3, which records the number of the video angle for playback, is set to the appropriate value.
  • This further embodiment of the present invention has been developed to allow vendors to publish video content on DVD-Video discs for playback on any DVD-Video player, where the content must be ⁇ unlocked' prior to viewing. This enables, amongst other things, pay-to-play applications, as illustrated by the following scenario:
  • the disc When prompting for the unlock code the disc displays an ⁇ identification code' which could be, for example, a four-digit code chosen at random by the player at run time.
  • the second example method can be modified to allow the identification code to be entered by the user using information that is either unique to that user or restricted to a small number of users. Examples are:
  • a PIN number supplied to the user This could take the form of a simple four-digit code, for example.
  • Video disc provides prompts by which the user enters each of the four digits in turn. This may be provided by a visualisation of a numeric keypad with which the user must use the standard DVD- Video remote control buttons (up, down, left, right, OK) to select the sequence of digits.
  • Example 5 A number that is specific to the current execution, which can be derived from the DVD-Video random number generator. 3. A number that is private to the user, such as a credit card number, or a customer code. This number would be entered in a similar way to item 1 above .
  • Example 5 A number that is specific to the current execution, which can be derived from the DVD-Video random number generator. 3. A number that is private to the user, such as a credit card number, or a customer code. This number would be entered in a similar way to item 1 above .
  • Example 5 A number that is specific to the current execution, which can be derived from the DVD-Video random number generator. 3. A number that is private to the user, such as a credit card number, or a customer code. This number would be entered in a similar way to item 1 above .
  • a crude function would simply return a success/fail outcome based upon, say, a PIN number.
  • the following pseudo-code returns 1 if the user enters the valid PIN code "1234" and 2 for all other codes.
  • Hash function is a function H that maps a message M (usually of arbitrary length) to a fixed length message digest'
  • a one-way hash function is a deterministic algorithm that compresses an arbitrary long message into a value of specified length - often referred to as a ⁇ fingerprint' - such that it is infeasible to find two distinct messages that have the same fingerprint.
  • Such functions are widely used in cryptography; popular methods include MD5, SHA and Snefru.
  • a simple destination function D based upon a Hash function H is:
  • Another example technique involves using a pair of keys as parameters to the destination function, with one key being generated by the player, and the second matching key being supplied by the vendor to unlock the content.
  • One implementation of this approach may operate as follows:
  • Ci random access code
  • Ref RND( 10,000) # Generate a random number 0... 9,999 Display Ref
  • ⁇ D' is the correct destination - 321 in this example.
  • the user enters this key and a destination is calculated and execution jumps to the corresponding PGC.
  • PIN codes above are used for illustrative purposes; in practice longer codes may be appropriate to provide high levels of security.
  • the destination function illustrated is very simple and insecure; in practice a one-way hash function would be preferable so that it cannot be easily inverted.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)
  • Television Signal Processing For Recording (AREA)
  • Management Or Editing Of Information On Record Carriers (AREA)

Abstract

L'accès à un produit audiovisuel (400) est commandé par l'intermédiaire de flux vidéo brouillés (1901, 1902). Des cellules (420) de données audiovisuelles (700) A, B, C1, D sont brouillées dans un premier et un second flux vidéo (1901, 1902). Une instruction de commutation (2011, 2021) de flux vidéo établit une commutation automatique entre un premier et un second flux vidéo (1901, 1902) pendant une reproduction, de sorte que lesdites cellules sont reproduites à partir d'un flux vidéo approprié (1901, 1902) à des moments appropriés. Des objets vidéo multi-angles (2020) maintiennent les cellules (420) dans un flux vidéo sélectionné (1902), et maintiennent des données C2 nulles ou erronées dans d'autres flux (1901).
EP04736214A 2003-06-05 2004-06-07 Flux video brouilles dans un produit audiovisuel Withdrawn EP1634290A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GBGB0312874.1A GB0312874D0 (en) 2003-06-05 2003-06-05 Controlling access to an audiovisual product
US48032203P 2003-06-20 2003-06-20
PCT/GB2004/002394 WO2004109679A1 (fr) 2003-06-05 2004-06-07 Flux video brouilles dans un produit audiovisuel

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EP1634290A1 true EP1634290A1 (fr) 2006-03-15

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EP04736213A Withdrawn EP1634289A1 (fr) 2003-06-05 2004-06-07 Donnees d'obscurcissement dans un produit audiovisuel
EP04736214A Withdrawn EP1634290A1 (fr) 2003-06-05 2004-06-07 Flux video brouilles dans un produit audiovisuel
EP04736223A Withdrawn EP1634291A1 (fr) 2003-06-05 2004-06-07 Deverrouillage d'un produit audiovisuel

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JP (3) JP4542089B2 (fr)
GB (3) GB2402543B (fr)
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GB2402542B (en) 2008-01-02
GB2402542A (en) 2004-12-08
GB2402543B (en) 2006-06-21
WO2004109679A1 (fr) 2004-12-16
JP4542089B2 (ja) 2010-09-08
GB0412601D0 (en) 2004-07-07
JP2006526864A (ja) 2006-11-24
GB2402543A (en) 2004-12-08
WO2004109678A1 (fr) 2004-12-16
JP4680892B2 (ja) 2011-05-11
GB2402541A (en) 2004-12-08
GB0412606D0 (en) 2004-07-07
WO2004109680A1 (fr) 2004-12-16
EP1634291A1 (fr) 2006-03-15
GB0412603D0 (en) 2004-07-07
EP1634289A1 (fr) 2006-03-15
GB2402541B (en) 2008-01-02
JP2007527588A (ja) 2007-09-27
JP2010123247A (ja) 2010-06-03

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