EP1559270A1 - Adaptive and progressive video stream scrambling - Google Patents

Adaptive and progressive video stream scrambling

Info

Publication number
EP1559270A1
EP1559270A1 EP03798956A EP03798956A EP1559270A1 EP 1559270 A1 EP1559270 A1 EP 1559270A1 EP 03798956 A EP03798956 A EP 03798956A EP 03798956 A EP03798956 A EP 03798956A EP 1559270 A1 EP1559270 A1 EP 1559270A1
Authority
EP
European Patent Office
Prior art keywords
distribution
stream
digital video
sequences according
modified
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.)
Ceased
Application number
EP03798956A
Other languages
German (de)
French (fr)
Inventor
Daniel Lecomte
Pierre Sarda
Daniela Parayre-Mitzova
Sébastien Georges
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.)
Nagra France SAS
Original Assignee
Medialive SA
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
Application filed by Medialive SA filed Critical Medialive SA
Publication of EP1559270A1 publication Critical patent/EP1559270A1/en
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/45—Management operations performed by the client for facilitating the reception of or the interaction with the content or administrating data related to the end-user or to the client device itself, e.g. learning user preferences for recommending movies, resolving scheduling conflicts
    • H04N21/466—Learning process for intelligent management, e.g. learning user preferences for recommending movies
    • H04N21/4667—Processing of monitored end-user data, e.g. trend analysis based on the log file of viewer selections
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/136—Incoming video signal characteristics or properties
    • H04N19/137—Motion inside a coding unit, e.g. average field, frame or block difference
    • H04N19/139—Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
    • H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/18—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a set of transform coefficients
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/48—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/85—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression
    • H04N19/88—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression involving rearrangement of data among different coding units, e.g. shuffling, interleaving, scrambling or permutation of pixel data or permutation of transform coefficient data among different blocks
    • H—ELECTRICITY
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    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/234—Processing of video elementary streams, e.g. splicing of video streams or manipulating encoded video stream scene graphs
    • H04N21/2347—Processing of video elementary streams, e.g. splicing of video streams or manipulating encoded video stream scene graphs involving video stream encryption
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
    • H04N21/254—Management at additional data server, e.g. shopping server, rights management server
    • H04N21/2541—Rights Management
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
    • H04N21/258—Client or end-user data management, e.g. managing client capabilities, user preferences or demographics, processing of multiple end-users preferences to derive collaborative data
    • H04N21/25866—Management of end-user data
    • H04N21/25875—Management of end-user data involving end-user authentication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
    • H04N21/266—Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel
    • H04N21/26613—Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel for generating or managing keys in general
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
    • H04N21/266—Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel
    • H04N21/2662—Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/44—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream or rendering scenes according to encoded video stream scene graphs
    • H04N21/4405—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream or rendering scenes according to encoded video stream scene graphs involving video stream decryption
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/45—Management operations performed by the client for facilitating the reception of or the interaction with the content or administrating data related to the end-user or to the client device itself, e.g. learning user preferences for recommending movies, resolving scheduling conflicts
    • H04N21/462—Content or additional data management, e.g. creating a master electronic program guide from data received from the Internet and a Head-end, controlling the complexity of a video stream by scaling the resolution or bit-rate based on the client capabilities
    • H04N21/4622—Retrieving content or additional data from different sources, e.g. from a broadcast channel and the Internet
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/45—Management operations performed by the client for facilitating the reception of or the interaction with the content or administrating data related to the end-user or to the client device itself, e.g. learning user preferences for recommending movies, resolving scheduling conflicts
    • H04N21/462—Content or additional data management, e.g. creating a master electronic program guide from data received from the Internet and a Head-end, controlling the complexity of a video stream by scaling the resolution or bit-rate based on the client capabilities
    • H04N21/4627—Rights management associated to the content
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/80—Generation or processing of content or additional data by content creator independently of the distribution process; Content per se
    • H04N21/83—Generation or processing of protective or descriptive data associated with content; Content structuring
    • H04N21/835—Generation of protective data, e.g. certificates
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/16—Analogue secrecy systems; Analogue subscription systems
    • H04N7/167—Systems rendering the television signal unintelligible and subsequently intelligible
    • H04N7/1675—Providing digital key or authorisation information for generation or regeneration of the scrambling sequence

Definitions

  • the present invention relates to the field of processing digital video streams. It is proposed in the present invention to provide a system for visually scrambling and recomposing digital video content.
  • the present invention relates more particularly to a device capable of securely transmitting a set of films of high visual quality to a television screen and / or to be recorded on the hard disk of a box connecting the teletransmission network to the display screen such as a television screen or a personal computer monitor, while preserving the audiovisual quality but avoiding any fraudulent use such as the possibility of making pirated copies of films or audiovisual programs recorded on the hard disk from the set-top box.
  • the invention relates to a method for distributing digital video sequences according to a nominal stream format consisting of a succession of so-called "frames" each comprising at least one digital block grouping together a certain number of coefficients corresponding to simple digitally coded video elements. according to a mode specified inside the stream concerned and used by all video decoders capable of displaying it in order to be able to decode it correctly.
  • This process includes: • a preparatory step consisting in modifying at least one of said coefficients,
  • Said complementary information is defined as a set consisting of data (for example coefficients describing the original digital stream or extracted from the original stream) and functions (for example, the substitution or permutation function).
  • a function is defined as containing at least one instruction relating data and operators. Said additional information describes the operations to be carried out to recover the original flow from the modified flow.
  • the original flow is reconstituted on the destination equipment from the modified main flow already present on the destination equipment and additional information sent in real time comprising data and functions executed using routines ( set of instructions) digital.
  • a reference of the prior art is the document WO 00 55089 A which presents a method and a system for scrambling compressed or uncompressed digital samples representing audio and video data, so that the content of these samples either degraded, but recognizable, or otherwise supplied with a given required quality.
  • a given number of Least Significant Bits (LSBs) of the data is scrambled for each sample frame by frame, adaptively according to the dynamics of the possible values, the most significant bits being unchanged.
  • This solution represents an encryption solution well known to those skilled in the art using encryption keys.
  • This method is not adaptive as a function of the content of the audiovisual stream, nor as a function of other characteristics such as the bit rate, the type of frames, the profile of the user or the different scalability layers characterizing it.
  • all the information initially contained in the flow remains inside the protected flow. This solution does not meet the criteria for high security, treated by the present invention.
  • a malicious user easily detects a false Image I of index n, because this image of index n is very different from the image I of index n-1 and of the image I of index n + 1; it can then easily replace it by the image I of index n-1 or of index n + 1, or by an image calculated by interpolation between the images I of index n-1 and n + 1, and thus recreate a flow very close to the original.
  • the solution proposed in this document therefore does not meet the criteria of high security and adaptability of the protection of video streams, objects of the present invention.
  • EP 1 033 880 A2 (SHARP KK) which relates to a method and a device for protecting digital video streams and still images, based on DCT and wavelet transformations.
  • the modifications applied to the space-frequency coefficients are of the type: scrambling of the sign bit of the coefficients, scrambling of the bits for improving the coefficients, scrambling of selected blocks and of motion vectors in the P and B images, choice of the appropriate coefficients belonging to a slice or to a frequency sub-band and swap them, rotate a block grouping frequency coefficients.
  • the protection is removed in a conventional manner known to those skilled in the art using decryption keys. This document does not correspond to the security objectives set in the present invention, since all the original data describing the flow are located inside the protected flow.
  • the document WO 00/31964 (ERICSSON) referenced by the prior art relates to a method and equipment for the partial encryption of images and their progressive transmission, a first part of the image is compressed at low quality, without encryption, and a second part (made up of two sections) of the image is encrypted, each section being encrypted with its own method and its own key.
  • This document presents a conventional encryption approach, and therefore does not meet the criteria and objectives of the present invention of high security, because all the information describing the content is present inside the protected stream.
  • document XP000997705 (Thomas KUNKELMANN and U e HORN) which deals with the protection of video streams coming from video encoders based on DCT.
  • this document proposes a method for partial encryption of the data, based on the property of partitioning the data, while leaving the two parts physically in the same stream, and based on the temporal and spatial scalabilities .
  • This document does not solve the problems dealt with by the present invention, since it proposes encryption techniques, well known to those skilled in the art, which swap the data inside the stream or add encryption keys, but by keeping inside the flow all the data describing it.
  • the prior art knows the document WO 01 69354 A3 (MICROSOFT CORPORATION) which relates to the protection of a digital product (software or audio or video content) by breaking it down into at least two portions.
  • the first portion is transmitted to the client equipment by physical means.
  • the second portion is transformed so that it can only be used by the client station concerned, then is transmitted entirely by the same process or else by a telecommunications network to this client station.
  • the client station receiving the two portions can modify the first portion as a function of a key transmitted by the server, from which two other keys are generated, so that this first portion is compatible with the second portion received.
  • the present invention intends to remedy the drawbacks of the prior art by proposing to apply adaptive and progressive scrambling as a function of the structure of the video bitstream and / or of its content.
  • the term “scrambling” is understood to mean the modification of a digital video stream by appropriate methods so that this stream remains in conformity with the standard with which it has been digitally encoded, while making it displayable. by a reader (or viewer or display or player), but altered from the point of view of human visual perception.
  • the term “descrambling” is understood to mean the process of restitution by appropriate methods of the initial stream, the video stream restored after descrambling being identical to the initial video stream.
  • adaptive and progressive scrambling is applied as a function of the structure of the video bitstream and / or its content, by changing the algorithms and / or the scrambling parameters as a function of the characteristics of the video stream. and user application, and this in order to achieve reliable protection, from the point of view of the deterioration of the original flow and resistance to piracy, for a minimal cost, while ensuring in the end the quality of service required by the spectator or the customer.
  • Different adaptations of the scrambling are applied, such as those mentioned below.
  • a digital video stream generally consists of sequences of images, grouped into groups of “Groups Of Pictures” (GOPs).
  • An image can be of type I (Intra), P (Predicted), B (Bidirectional).
  • An S plane is a plane containing a static object, which is a still image describing the background of the image or a plane coded using a prediction based on global motion compensation (GMC) from a reference plane , previous.
  • the images I are the reference images, they are fully coded and are therefore of large size and do not contain information on the movement.
  • the planes P are planes predicted from previous planes, whether I and / or P by vectors of movement in a single direction, called forward "for ard”.
  • the planes B are said to be bidirectional, they are linked to the planes I and / or P preceding or following them by motion vectors in the two temporal directions (forward and backward or “back ard”).
  • Motion vectors represent two-dimensional vectors used for motion compensation, which provide the difference in coordinates between a part of the current image and a part of the reference image.
  • An adaptation is applied according to the scenes contained in the video stream: the video streams contain different sequences in which the proportion between the fixed, static and dynamic shots (from the point of view of the content of the scenes in the stream) varies widely.
  • the protection which can be effective for dynamic scenes containing a lot of movements, can be ineffective for static scenes with few movements. Knowing the content of the video streams beforehand, we can define a change in algorithms and / or scrambling parameters depending on the different scenes — landscape, actions, videoconference type, cartoons type, etc.
  • An adaptation of the parameters is also applied as a function of the size of the frames (in number of pixels). The same parametric combination can cause much greater degradations for flows having small frames and vice versa.
  • a parametric adaptation is also applied according to the spatial scalability characterizing certain video streams, relating to the change in size in pixels.
  • An adaptation of the scrambling parameters is also applied as a function of the granular scalability characterizing certain video streams.
  • granular scalability from the English expression “granular scalability” used in the MPEG-4 standard which characterizes an encoder capable of encoding or a decoder capable of decoding an ordered set of bit streams so as to produce or reconstruct a multi-layered sequence.
  • granularity as the amount of information that can be transmitted per layer of a system characterized by any scalability, the system is then also granular.
  • An adaptation is also applied as a function of the bit rate in number of bits per second (bits / s) of the video stream, whether constant or variable.
  • adaptive scrambling is applied according to the types of objects, the profile ("profile"), the level ("level”), designating the complexity and the options used when building the video stream.
  • An adaptation is applied as a function of the number of frames per second of the video stream.
  • Progressive scrambling is also applied, so that the user begins to watch the unscrambled video stream. Then, we start with a light scrambling which we reinforce more and more, until the flow becomes entirely tangled.
  • the aim is to arouse the user's interest in the video stream, but by removing their viewing rights if the latter has not purchased them.
  • One embodiment of this application is to scramble the video stream with one and / or given algorithms by gradually modifying the scrambling parameters over a determined period of time so as to increase the inconvenience, until arriving at a completely scrambled stream. .
  • Adaptive scrambling is generally carried out as a function of the content, characteristics, structure and composition of the digital stream defined by a given standard.
  • Scrambling is also carried out with a random generation of the parametric combinations to be applied for scrambling the video stream.
  • a robust and difficult to attack protection is provided, which cannot be hacked by a malicious person.
  • the drawback which could arise is that, following this random parametric generation, certain sequences may not be sufficiently scrambled, due to the fact that the random generator does not take account of the content of the streams.
  • the invention relates in its most general sense to a method for the distribution of digital video sequences according to a nominal flow format constituted by a succession of so-called "frames" each comprising at least one block grouping a plurality of coefficients corresponding to elements digitally coded simple visuals, the method comprising a step of modifying at least one block of the original flow characterized in that said modification step acts adaptively on said original flow as a function of at least some of the characteristics representative of the structure, content and parameters of the original video stream, the recipient's profile, and external events.
  • the modification step consists in replacing part of said coefficients to produce on the one hand a main video stream in nominal format and on the other hand complementary modification information allowing the reconstruction of the original stream by a decoder of the recipient equipment, the scope of the modifications being variable and determined by said representative characteristics.
  • the modified main stream is recorded on the destination equipment prior to the transmission of additional information on the recipient equipment.
  • the modified main stream and the additional information are transmitted together in real time.
  • said additional modification information comprises at least one digital routine capable of executing a function.
  • said additional modification information is subdivided into at least two sub-parts.
  • said sub-parts of the additional modification information may be distributed by different media.
  • said sub-parts of the additional modification information can be distributed by the same medium.
  • the additional information is transmitted on a physical vector.
  • the additional information is transmitted online.
  • said digital images use wavelet-based technologies.
  • the video streams are organized in frames consisting of blocks corresponding to at least one plane I, a plane P corresponding to the differences between an image called P, at least one other image I or P, also being able to contain at least one plane B corresponding to the differences between two images P, and planes S.
  • said images I, P, B and S are modified in a differentiated manner according to their type, in particular I, P, B or S.
  • the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the video stream in terms of structure of the groups of images GOPs, and of the proportions between the quantities of images I, P, B present in video streams, the latter being characterized by a constant or variable number of shots per second or characterized by temporal scalability.
  • the images I, P, B and S are modified in a differentiated manner as a function of the number of planes (frames) per second constant or variable for the flows characterized by temporal scalability.
  • the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the scenes contained in the flow in terms of fixed, static or dynamic shots and / or visual forms contained, and / or as a function of granular scalability.
  • the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the flows in terms of the size of the planes
  • the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the streams in terms of bit rate per second of the video stream.
  • the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the video streams in terms of composition in objects, profiles and levels.
  • the images I, P, B and S are modified in a progressive manner increasing the degradation effect until the video stream is completely scrambled.
  • the images I, P, B and S are modified with a random generation of the scrambling parameters and configurations.
  • the scrambling is adaptive as a function of the content, characteristics, structure and composition of the video stream, the nominal stream format of which is defined by the MPEG-1 standard or
  • MPEG-2 or MPEG-4 or others are examples.
  • the method comprises a preliminary step of analog / digital conversion in a structured format, the method being applied to an analog video signal.
  • the video stream reconstituted from the modified main stream and additional information is strictly identical to the original stream.
  • the present invention also relates to a system for the distribution of video sequences comprising a video server comprising means for broadcasting a stream modified in accordance with any one of the preceding methods, and a plurality of equipment provided with a circuit scrambling, characterized in that the server further comprises means for recording the digital profile of each recipient and means for controlling the modification means as a function of input variables corresponding to at least some of the characteristics representative of the structure, content and parameters of the original video stream, the recipient's profile, and external events.
  • FIG. 1 illustrates a particular embodiment of the client-server system according to the invention. Let us consider an example of realization.
  • FIG. 1 represents a particular embodiment of the client-server system in accordance with
  • the MPEG-2 video stream that one wishes to secure (1) is passed to an analysis (121) and scrambling (122) system which will generate a modified main stream and additional information at the output.
  • the original stream (1) can be directly in digital form (10) or in analog form (11). In the latter case, the analog stream (11) is converted by an encoder not shown in a digital format (10).
  • a first stream (124) in MPEG-2 format of format identical to the digital input stream (1) apart from the fact that some of the coefficients, values and / or vectors have been modified, is placed in an output buffer memory (125).
  • the complementary information (123), in any format, contains the references of the parts of the video samples which have been modified and is placed in the buffer (126).
  • the analysis (121) and scrambling (122) system decides which adaptive scrambling to apply and which parameters of the flow to modify and also according to the rights of the client, from which way to apply the modifications, for example progressive or not.
  • the MPEG-2 stream (125) is then transmitted, via a broadband network (4) of the radio type, cable, satellite, etc., to the client (8), and more precisely in its memory (81) of the RAM type, ROM, hard drive.
  • the recipient (8) requests to view a video sequence present in his memory (81)
  • two possibilities are possible: - either the recipient (8) does not have the necessary rights to view the video sequence.
  • the stream (125) generated by the scrambling system (122) present in its memory (81) is passed to the synthesis system (82), which does not modify it and transmits it identically to a reader.
  • classic video (83) and its content, strongly degraded visually, is displayed by the player (83) on a screen (9).
  • the recipient (8) has the rights to watch the video sequence.
  • the server 12 transmits the appropriate additional information (126) via the link (6), corresponding to the type of scrambling carried out.
  • the synthesis system makes a display request to the server (12) containing the information necessary (126) for recovering the original video sequence (1).
  • the server (12) then sends via the link (6) via telecommunication networks such as analog or digital telephone line, DSL (Digital Subscriber Line), BLR (Local Radio Loop), DAB (Digital Audio Broadcasting) or digital mobile telecommunications. (GSM, GPRS, UMTS), the additional information (126) allowing the reconstruction of the video sequence so that the client (8) can view and / or store the video sequence.
  • GSM Global System for Mobile Communications
  • the synthesis system (82) then proceeds to descramble the video by reconstructing the original stream by combining the modified main stream (125) and the additional information (126).
  • the video stream thus obtained at the output of the synthesis system (82) is then transmitted to the conventional video player (83) and the original video film is displayed on the screen (9).

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Abstract

The invention relates to a method of distributing digital video sequences according to a nominal stream format, said sequences consisting of a series of frames. Each of the aforementioned frames comprises at least one block containing numerous coefficients that correspond to simple digitally-encoded visual elements. The inventive method comprises a modification step, whereby at least one block of the original stream is modified. The invention is characterised in that, during the aforementioned modification step, the original stream is modified in an adaptive manner according to at least one part of the characteristics representative of the structure, contents and parameters of the original video stream, the profile of the recipient and external events. In one particular embodiment, the modification step consists in replacing one part of said coefficients in order to produce (i) a main video stream with the nominal format and (ii) complementary modification information which enables the original stream to be reconstructed by a decoder belonging to the recipient equipment. The range of said modifications is variable and determined by the above-mentioned representative characteristics. The invention also relates to a system which is used to implement the inventive method.

Description

EMBROUILLAGE ADAPTATIF ET PROGRESSIF DE FLUX VIDEO ADAPTIVE AND PROGRESSIVE INTERFERENCE OF VIDEO STREAMS
La présente invention se rapporte au domaine du traitement de flux vidéo numériques . On se propose dans la présente invention de fournir un système permettant d'embrouiller visuellement et recomposer un contenu vidéo numérique.The present invention relates to the field of processing digital video streams. It is proposed in the present invention to provide a system for visually scrambling and recomposing digital video content.
La présente invention se rapporte plus particulièrement à un dispositif capable de transmettre de façon sécurisée un ensemble de films de haute qualité visuelle vers un écran de télévision et/ou pour être enregistré sur le disque dur d'un boîtier reliant le réseau de télétransmission à l'écran de visualisation tel qu'un écran de télévision ou un moniteur d'ordinateur personnel, tout en préservant la qualité audiovisuelle mais en évitant toute utilisation frauduleuse comme la possibilité de faire des copies pirates de films ou de programmes audiovisuels enregistrés sur le disque dur du boîtier décodeur. L'invention concerne un procédé pour la distribution de séquences vidéos numériques selon un format de flux nominal constitué par une succession de trames dites « frames » comprenant chacune au moins un bloc numérique regroupant un certain nombre de coefficients correspondant à des éléments vidéo simples codés numériquement selon un mode précisé à l'intérieur du flux concerné et utilisé par tous les décodeurs vidéos capables de l'afficher afin de pouvoir la décoder correctement. Ce procédé comporte : • une étape préparatoire consistant à modifier au moins un desdits coefficients,The present invention relates more particularly to a device capable of securely transmitting a set of films of high visual quality to a television screen and / or to be recorded on the hard disk of a box connecting the teletransmission network to the display screen such as a television screen or a personal computer monitor, while preserving the audiovisual quality but avoiding any fraudulent use such as the possibility of making pirated copies of films or audiovisual programs recorded on the hard disk from the set-top box. The invention relates to a method for distributing digital video sequences according to a nominal stream format consisting of a succession of so-called "frames" each comprising at least one digital block grouping together a certain number of coefficients corresponding to simple digitally coded video elements. according to a mode specified inside the stream concerned and used by all video decoders capable of displaying it in order to be able to decode it correctly. This process includes: • a preparatory step consisting in modifying at least one of said coefficients,
• une étape de transmission• a transmission step
- d'un flux principal conforme au format nominal, constitué par des plans contenant les blocs modifiés au cours de l'étape préparatoire et- a main flow conforming to the nominal format, consisting of plans containing the blocks modified during the preparatory stage and
- par une voie séparée dudit flux principal d'une information numérique complémentaire permettant de reconstituer le flux originel à partir du calcul, sur l'équipement destinataire, en fonction dudit flux principal et de ladite information complémentaire. On définit ladite information complémentaire en tant qu'un ensemble constitué de données (par exemple des coefficients décrivant le flux numérique originel ou extraits du flux originel) et de fonctions (par exemple, la fonction substitution ou permutation). Une fonction est définie comme contenant au moins une instruction mettant en rapport des données et des opérateurs. Ladite information complémentaire décrit les opérations à effectuer pour récupérer le flux original à partir du flux modifié.- by a separate channel from said main stream of complementary digital information making it possible to reconstruct the original stream from the calculation, on the recipient equipment, according to said main stream and said complementary information. Said complementary information is defined as a set consisting of data (for example coefficients describing the original digital stream or extracted from the original stream) and functions (for example, the substitution or permutation function). A function is defined as containing at least one instruction relating data and operators. Said additional information describes the operations to be carried out to recover the original flow from the modified flow.
La reconstitution du flux originel s'effectue sur l'équipement destinataire à partir du flux principal modifié déjà présent sur l'équipement destinataire et de l'information complémentaire envoyée en temps réel comprenant des données et des fonctions exécutées à l'aide de routines (ensemble d'instructions) numériques.The original flow is reconstituted on the destination equipment from the modified main flow already present on the destination equipment and additional information sent in real time comprising data and functions executed using routines ( set of instructions) digital.
Une référence de 1 ' art antérieur est le document WO 00 55089 A qui présente une méthode et un système pour l'embrouillage d'échantillons numériques compressés ou non- compressés représentant des données audio et vidéo, de manière à ce que le contenu de ces échantillons soit dégradé, mais reconnaissable, ou sinon fourni avec une qualité requise donnée. Un nombre donné de LSBs (« Least Significant Bits » , bits de poids le plus faible en anglais) des données est embrouillé pour chaque échantillon trame par trame, de manière adaptative en fonction de la dynamique des valeurs possibles, les bits de poids le plus fort étant inchangés. Cette solution représente une solution de cryptage bien connue par l'homme de l'art à l'aide de clés de cryptage. Cette méthode n'est pas adaptative en fonction du contenu du flux audiovisuel, ni en fonction d'autres caractéristiques telles que le débit, le type de trames, le profil de l'utilisateur ou les différentes couches de scalabilité le caractérisant. De plus, toutes les informations initialement contenues dans le flux restent à l'intérieur du flux protégé. Cette solution ne répond pas aux critères de forte sécurisation, traités par la présente invention.A reference of the prior art is the document WO 00 55089 A which presents a method and a system for scrambling compressed or uncompressed digital samples representing audio and video data, so that the content of these samples either degraded, but recognizable, or otherwise supplied with a given required quality. A given number of Least Significant Bits (LSBs) of the data is scrambled for each sample frame by frame, adaptively according to the dynamics of the possible values, the most significant bits being unchanged. This solution represents an encryption solution well known to those skilled in the art using encryption keys. This method is not adaptive as a function of the content of the audiovisual stream, nor as a function of other characteristics such as the bit rate, the type of frames, the profile of the user or the different scalability layers characterizing it. In addition, all the information initially contained in the flow remains inside the protected flow. This solution does not meet the criteria for high security, treated by the present invention.
L'art antérieur connaît également par la demande de brevet français WO 01/97520 « Dispositif d'interfaçage vidéo, système de distribution et méthode de transfert de programmes et de séquences vidéo encodées à travers le réseau de communication » un dispositif pour la diffusion sécurisée de flux vidéo protégés. La protection du flux vidéo est effectuée en remplaçant certaines images I originales par des « fausses » images I ou en permutant certaines images I entre elles. Les images I originales extraites du flux vidéo sont stockées séparément du flux protégé et sont envoyées à l'utilisateur lorsqu'il souhaite visualiser la vidéo. Ainsi, remplacer les images I originales par des « fausses » images I modifie la taille du flux protégé par rapport au flux original. Par ailleurs, un usager mal intentionné détecte facilement une fausse Image I d'indice n, car cette image d'indice n est très différente de l'image I d'indice n-1 et de l'image I d'indice n+1 ; il peut alors facilement la remplacer par l'image I d'indice n-1 ou d'indice n+1, ou par une image calculée par interpolation entre les images I d'indice n-1 et n+1, et recréer ainsi un flux très proche de l'original. La solution proposée dans ce document ne répond donc pas au critère de haute sécurité et d' adaptabilité de la protection de flux vidéos, objets de la présente invention.The prior art also knows from French patent application WO 01/97520 "Video interfacing device, distribution system and method for transferring programs and encoded video sequences through the communication network" a device for secure broadcasting. protected video streams. The video stream is protected by replacing certain original I images with “false” I images or by swapping certain I images between them. The original I images extracted from the video stream are stored separately from the protected stream and are sent to the user when he wishes to view the video. Thus, replacing the original I images with “false” I images modifies the size of the protected stream compared to the original stream. Furthermore, a malicious user easily detects a false Image I of index n, because this image of index n is very different from the image I of index n-1 and of the image I of index n + 1; it can then easily replace it by the image I of index n-1 or of index n + 1, or by an image calculated by interpolation between the images I of index n-1 and n + 1, and thus recreate a flow very close to the original. The solution proposed in this document therefore does not meet the criteria of high security and adaptability of the protection of video streams, objects of the present invention.
Un autre document connu par l'art antérieur est le document EP 1 033 880 A2 (SHARP KK) qui est relatif à un procédé et un dispositif de protection des flux vidéo numériques et des images fixes, basés sur les transformations DCT et ondelettes. Les modifications appliquées aux coefficients spatio-fréquentiels sont de type : brouillage du bit de signe des coefficients, brouillage des bits d'amélioration des coefficients, brouillage de blocs choisis et de vecteurs de mouvement dans les images P et B, choix des coefficients appropriés appartenant à une tranche « slice » ou à une sous bande fréquentielle et les permuter, effectuer la rotation d'un block regroupant des coefficients fréquentiels . La protection est enlevée de façon classique connue par l'homme de l'art à l'aide de clés de décryptage. Ce document ne correspond pas aux objectifs de sécurisation fixés dans la présente invention, car toutes les données originales décrivant le flux se trouvent à l'intérieur du flux protégé.Another document known by the prior art is document EP 1 033 880 A2 (SHARP KK) which relates to a method and a device for protecting digital video streams and still images, based on DCT and wavelet transformations. The modifications applied to the space-frequency coefficients are of the type: scrambling of the sign bit of the coefficients, scrambling of the bits for improving the coefficients, scrambling of selected blocks and of motion vectors in the P and B images, choice of the appropriate coefficients belonging to a slice or to a frequency sub-band and swap them, rotate a block grouping frequency coefficients. The protection is removed in a conventional manner known to those skilled in the art using decryption keys. This document does not correspond to the security objectives set in the present invention, since all the original data describing the flow are located inside the protected flow.
Une autre référence de l'art antérieur concernant la protection adaptative de flux visuel est le document US 5 754 658 (INTEL Corporation) qui est relatif à une méthode et un dispositif de stockage de données encodees. Les données sont cryptées par différentes techniques de cryptage, et le cryptage est adaptatif en fonction de la surcharge du microprocesseur de l'encodeur et/ou du décodeur. La protection n'est pas adaptative en fonction de la dégradation visuelle souhaitée ou en fonction de la structure et du contenu des flux vidéos. De plus, les protections appliquées sont des diverses techniques de cryptage et toutes les données initialement présentes restent intégralement dans le flux protégé. Un autre document représentatif de l'art antérieur est le document US 2001/0053222 Al, cette solution est une solution de cryptage classique à base de clés et même si le cryptage est complexe, quatre clés étant utilisées, toutes les informations nécessaires à la reconstitution sont présentes dans le flux vidéo protégé.Another reference in the prior art relating to adaptive protection of visual flow is the document US Pat. No. 5,754,658 (INTEL Corporation) which relates to a method and a device for storing encoded data. The data is encrypted by different encryption techniques, and the encryption is adaptive depending on the overload of the encoder microprocessor and / or the decoder. The protection is not adaptive according to the desired visual degradation or according to the structure and content of the video streams. In addition, the protections applied are various encryption techniques and all the data initially present remains entirely in the protected stream. Another document representative of the prior art is the document US 2001/0053222 A1, this solution is a conventional encryption solution based on keys and even if the encryption is complex, four keys being used, all the information necessary for the reconstitution are present in the protected video stream.
Le document WO 00/31964 (ERICSSON) référencé par l'art antérieur est relatif à une méthode et à un équipement pour le cryptage partiel d'images et leur transmission progressive, une première partie de l'image est compressée à faible qualité, sans cryptage, et une seconde partie (composée de deux sections) de l'image est cryptée, chaque section étant cryptée avec sa propre méthode et sa propre clé. Ce document présente une démarche de cryptage classique, et donc ne répond pas aux critères et objectifs de la présente invention de forte sécurité, car toute l'information décrivant le contenu est présente à l'intérieur du flux protégé.The document WO 00/31964 (ERICSSON) referenced by the prior art relates to a method and equipment for the partial encryption of images and their progressive transmission, a first part of the image is compressed at low quality, without encryption, and a second part (made up of two sections) of the image is encrypted, each section being encrypted with its own method and its own key. This document presents a conventional encryption approach, and therefore does not meet the criteria and objectives of the present invention of high security, because all the information describing the content is present inside the protected stream.
L'art antérieur connaît également le document XP000997705 (Thomas KUNKELMANN and U e HORN) qui traite de la protection de flux vidéo issus d'encodeurs vidéos à base de DCT. Afin de réduire les ressources pour le cryptage, ce document propose un procédé pour un cryptage partiel des données, basé sur la propriété de partitionnement des données, tout en laissant les deux parties physiquement dans le même flux, et basé sur les scalabilités temporelle et spatiale. Ce document ne résout pas les problèmes traités par la présente invention, car il propose des techniques de cryptage, bien connues par l'homme de l'art, qui permutent les données à l'intérieur du flux ou rajoutent des clés de cryptage, mais en gardant à l'intérieur du flux toutes les données le décrivant. Dans l'optique de séparer un produit numérique en différentes portions afin de le protéger, l'art antérieur connaît le document WO 01 69354 A3 (MICROSOFT CORPORATION) qui porte sur la protection d'un produit numérique (logiciel ou contenu audio ou vidéo) en le décomposant en au moins deux portions. La première portion est transmise à l'équipement client par un moyen physique. La deuxième portion est transformée de façon à n'être exploitable que par le poste client concerné, puis est transmise intégralement par le même procédé ou alors par un réseau de télécommunication à ce poste client. Le poste client recevant les deux portions peut modifier la première portion en fonction d'une clé transmise par le serveur, à partir de laquelle sont générées deux autres clés, afin que cette première portion soit compatible avec la deuxième portion reçue. Ces deux portions sont re-combinées ensemble afin de restituer un produit binaire modifié en substance équivalent au produit d'origine, mais différent en terme de configuration, et adéquat pour l'équipement client. Ce document ne présente pas d'exemple de réalisation de traitement effectué sur les deux portions, aucun format numérique vidéo n'est cité. Par ailleurs, la conformité avec le flux d'origine d'aucune des deux parties initialement séparées n'est décrite ni suggérée. Aussi, une séparation du produit numérique en deux portions est effectuée, mais tous les éléments du produit numérique restent dans les deux portions transmises à l'utilisateur. Les deux portions cryptées sont envoyées par deux voies différentes et en deux étapes, mais sont envoyées intégralement. Cette invention ne répond pas aux critères de sécurisation et adaptation fixée dans la présente invention d'une part du fait de l'utilisation de méthode de cryptage et d'autre part de l'adaptation limitée à l'équipement de chaque utilisateur. La présente invention entend remédier aux inconvénients de l'art antérieur en proposant d'appliquer un embrouillage adaptatif et progressif en fonction de la structure du bitstream vidéo et/ou de son contenu. Dans la présente invention, on entend sous le terme « embrouillage » la modification d'un flux vidéo numérique par des méthodes appropriées de manière à ce que ce flux reste conforme à la norme avec laquelle il a été encodé numériquement, tout en le rendant affichable par un lecteur (ou visionneur ou afficheur ou player), mais altéré du point de vue de la perception visuelle humaine.The prior art also knows document XP000997705 (Thomas KUNKELMANN and U e HORN) which deals with the protection of video streams coming from video encoders based on DCT. In order to reduce the resources for encryption, this document proposes a method for partial encryption of the data, based on the property of partitioning the data, while leaving the two parts physically in the same stream, and based on the temporal and spatial scalabilities . This document does not solve the problems dealt with by the present invention, since it proposes encryption techniques, well known to those skilled in the art, which swap the data inside the stream or add encryption keys, but by keeping inside the flow all the data describing it. With a view to separating a digital product into different portions in order to protect it, the prior art knows the document WO 01 69354 A3 (MICROSOFT CORPORATION) which relates to the protection of a digital product (software or audio or video content) by breaking it down into at least two portions. The first portion is transmitted to the client equipment by physical means. The second portion is transformed so that it can only be used by the client station concerned, then is transmitted entirely by the same process or else by a telecommunications network to this client station. The client station receiving the two portions can modify the first portion as a function of a key transmitted by the server, from which two other keys are generated, so that this first portion is compatible with the second portion received. These two portions are re-combined together in order to restore a binary product modified in substance equivalent to the original product, but different in terms of configuration, and suitable for customer equipment. This document does not present an example of processing carried out on the two portions, no digital video format is cited. Furthermore, compliance with the original workflow of neither of the two initially separate parts is described or suggested. Also, a separation of the digital product into two portions is carried out, but all the elements of the digital product remain in the two portions transmitted to the user. The two encrypted portions are sent in two different ways and in two stages, but are sent in full. This invention does not meet the security and adaptation criteria fixed in the present invention on the one hand due to the use of encryption method and on the other hand from the adaptation limited to the equipment of each user. The present invention intends to remedy the drawbacks of the prior art by proposing to apply adaptive and progressive scrambling as a function of the structure of the video bitstream and / or of its content. In the present invention, the term “scrambling” is understood to mean the modification of a digital video stream by appropriate methods so that this stream remains in conformity with the standard with which it has been digitally encoded, while making it displayable. by a reader (or viewer or display or player), but altered from the point of view of human visual perception.
Dans la présente invention, on entend sous le terme « désembrouillage » le processus de restitution par des méthodes appropriées du flux initial, le flux vidéo restitué après le désembrouillage étant identique au flux vidéo initial.In the present invention, the term “descrambling” is understood to mean the process of restitution by appropriate methods of the initial stream, the video stream restored after descrambling being identical to the initial video stream.
Beaucoup de systèmes d' embrouillage ont un effet immédiat, soit le flux initial est totalement embrouillé, soit le flux initial n'est pas du tout embrouillé, aussi généralement différentes séquences vidéos peuvent être embrouillées avec le même algorithme et les mêmes paramètres de réglage. De nombreuses protections utilisées ne changent pas l'embrouillage d'un flux vidéo en fonction de son contenu.Many scrambling systems have an immediate effect, either the initial flow is fully scrambled, or the initial flow is not at all scrambled, so generally different video sequences can be scrambled with the same algorithm and settings. Many protections used do not change the scrambling of a video stream according to its content.
Dans la présente invention, on applique un embrouillage adaptatif et progressif en fonction de la structure du flux (bitstream) vidéo et/ou de son contenu, en changeant les algorithmes et/ou les paramètres de l'embrouillage en fonction des caractéristiques du flux vidéo et de l'application utilisateur, et cela dans le but de réaliser une protection fiable, du point de vue de la détérioration du flux d'origine et de la résistance au piratage, pour un coût minimal, tout en assurant à la fin la qualité de service requise par le spectateur ou le client. On applique différentes adaptations de l'embrouillage, comme par exemple celles citées ci-dessous. Un flux vidéo numérique est généralement constitué de séquences d'images, regroupées en groupes d'images « Groups Of Pictures) (GOPs). Une image peut être de type I (Intra), P (Prédite), B (Bidirectionnelle). Un plan S est un plan contenant un objet statique, qui est une image fixe décrivant le fond de l'image ou bien un plan codé en utilisant une prédiction basée sur la compensation de mouvement globale (GMC) à partir d'un plan de référence, antérieur. Les images I sont les images de référence, elles sont entièrement codées et sont donc de taille élevée et ne contiennent pas d'information sur le mouvement. Les plans P sont des plans prédits à partir de plans précédents, que ce soit I et/ou P par des vecteurs de mouvement dans une seule direction, dite en avant « for ard ». Les plans B sont dits bidirectionnels, ils sont liés aux plans I et/ou P les précédant ou les suivant par des vecteurs de mouvement dans les deux directions temporelles (en avant et en arrière ou « back ard »). Les vecteurs de mouvement représentent des vecteurs bidimensionnels utilisés pour la compensation de mouvements, qui procurent la différence de coordonnées entre une partie de l'image courante et une partie de l'image de référence. On applique une adaptation en fonction des scènes contenues dans le flux vidéo : les flux vidéo contiennent différentes séquences dans lesquelles la proportion entre les plans fixes, statiques et dynamiques (du point de vue du contenu des scènes du flux) varie largement. La protection qui peut être efficace pour des scènes dynamiques contenant beaucoup de mouvements, peut s'avérer inefficace pour des scènes statiques avec peu de mouvements. Connaissant le contenu des flux vidéo au préalable, on peut définir un changement d'algorithmes et/ou de paramètres d' embrouillage en fonction des différentes scènes—paysage, actions, type vidéoconférence, type dessins animés, etc.. En adaptant ainsi les paramètres, on peut protéger la totalité de la scène ou bien juste une partie donnée, mais qui rendra la séquence non regardable, et on va réduire considérablement la taille de ladite « information complémentaire ». Par exemple, dans un flux de type « vidéo conférence », il suffit d'embrouiller les personnages uniquement et non la totalité comprenant aussi le fond fixe. En fonction des scènes contenues dans le flux, on peut effectuer l'embrouillage de ce dernier par deux procédés différents :In the present invention, adaptive and progressive scrambling is applied as a function of the structure of the video bitstream and / or its content, by changing the algorithms and / or the scrambling parameters as a function of the characteristics of the video stream. and user application, and this in order to achieve reliable protection, from the point of view of the deterioration of the original flow and resistance to piracy, for a minimal cost, while ensuring in the end the quality of service required by the spectator or the customer. Different adaptations of the scrambling are applied, such as those mentioned below. A digital video stream generally consists of sequences of images, grouped into groups of “Groups Of Pictures” (GOPs). An image can be of type I (Intra), P (Predicted), B (Bidirectional). An S plane is a plane containing a static object, which is a still image describing the background of the image or a plane coded using a prediction based on global motion compensation (GMC) from a reference plane , previous. The images I are the reference images, they are fully coded and are therefore of large size and do not contain information on the movement. The planes P are planes predicted from previous planes, whether I and / or P by vectors of movement in a single direction, called forward "for ard". The planes B are said to be bidirectional, they are linked to the planes I and / or P preceding or following them by motion vectors in the two temporal directions (forward and backward or “back ard”). Motion vectors represent two-dimensional vectors used for motion compensation, which provide the difference in coordinates between a part of the current image and a part of the reference image. An adaptation is applied according to the scenes contained in the video stream: the video streams contain different sequences in which the proportion between the fixed, static and dynamic shots (from the point of view of the content of the scenes in the stream) varies widely. The protection which can be effective for dynamic scenes containing a lot of movements, can be ineffective for static scenes with few movements. Knowing the content of the video streams beforehand, we can define a change in algorithms and / or scrambling parameters depending on the different scenes — landscape, actions, videoconference type, cartoons type, etc. By thus adapting the parameters, we can protect the entire scene or just a given part, but which will make the sequence invisible, and we will reduce considerably the size of said "additional information". For example, in a “video conference” type stream, it suffices to confuse the characters only and not the whole including also the fixed background. Depending on the scenes contained in the stream, it can be scrambled by two different processes:
- soit avec un algorithme qui effectue au préalable la détection des formes et/ou des mouvements et l'analyse de la scène pour délimiter la zone à embrouiller ; - soit sans détection des formes et analyse de la scène, mais en appliquant les combinaisons paramétriques appropriées pour détériorer la ou les zone(s) voulue(s). Par exemple, la détérioration des vecteurs de mouvement perturbe essentiellement toutes les parties en mouvement, et très peu le décor.- either with an algorithm which performs the detection of shapes and / or movements and analysis of the scene beforehand to delimit the area to be scrambled; - either without detecting the shapes and analyzing the scene, but by applying the appropriate parametric combinations to deteriorate the desired area (s). For example, the deterioration of motion vectors disrupts essentially all moving parts, and very little the decor.
On applique aussi une adaptation en fonction de la structure du flux vidéo, notamment en fonction de la longueur des groupes de plans vidéos (GOPs) déterminant la proportion entre le nombre des images I, P, B. Si on a une combinaison paramétrique qui détériore uniquement les images I et si la période GOP est longue, l'embrouillage peut ne pas être efficace.We also apply an adaptation according to the structure of the video stream, in particular according to the length of the groups of video planes (GOPs) determining the proportion between the number of images I, P, B. If we have a parametric combination which deteriorates only I images and if the GOP period is long, scrambling may not be effective.
On applique aussi une adaptation des paramètres en fonction du type du plan (I, P, B, S). On applique également une adaptation des paramètres en fonction de la taille des trames (en nombre de pixels). Une même combinaison paramétrique peut provoquer des dégradations beaucoup plus importantes pour des flux ayant des trames de petite taille et vice versa. On applique une adaptation paramétrique également en fonction de la scalabilité spatiale caractérisant certains flux vidéos, relative au changement de taille en pixels. On définit la notion de « scalabilité » à partir du mot anglais « scalability » qui caractérise un encodeur capable d'encoder ou un décodeur capable de décoder un ensemble ordonné de flux binaires de façon à produire ou reconstituer une séquence multi couches .One also applies an adaptation of the parameters according to the type of the plan (I, P, B, S). An adaptation of the parameters is also applied as a function of the size of the frames (in number of pixels). The same parametric combination can cause much greater degradations for flows having small frames and vice versa. A parametric adaptation is also applied according to the spatial scalability characterizing certain video streams, relating to the change in size in pixels. We define the notion of “scalability” from the English word “scalability” which characterizes an encoder capable of encoding or a decoder capable of decoding an ordered set of bit streams so as to produce or reconstruct a multilayer sequence.
On applique également une adaptation des paramètres de l'embrouillage en fonction de la scalabilité granulaire caractérisant certains flux vidéos. On définit la notion « scalabilité granulaire » à partir de l'expression en anglais « granular scalability » utilisée dans la norme MPEG-4 qui caractérise un encodeur capable d'encoder ou un décodeur capable de décoder un ensemble ordonné de flux binaires de façon à produire ou reconstituer une séquence multi couches . On définit la granularité comme la quantité d'informations susceptible d'être transmise par couche d'un système caractérisé par une scalabilité quelconque, le système est alors aussi granulaire. On applique également une adaptation en fonction du débit en nombre de bits par seconde (bits/s) du flux vidéo, qu'il soit constant ou variable. Par exemple, un embrouillage efficace pour un débit de 2 Mbits/s s'avère moins efficace pour des débits beaucoup plus élevés . Pour certains flux plus complexes (comme ceux du type MPEG-4 ) , on applique un embrouillage adaptatif en fonction des types d'objets, du profil (« profile »), du niveau ( « level » ) , désignant la complexité et les options utilisées lors de la construction du flux vidéo. On applique une adaptation en fonction du nombre de trames par seconde du flux vidéo. Pour certains flux se caractérisant par une scalabilité temporelle, on applique un embrouillage adaptatif en fonction du nombre de trames par seconde variable. On applique aussi un embrouillage progressif, de manière à ce que l'utilisateur commence à regarder le flux vidéo non embrouillé. Ensuite, on commence par un embrouillage léger qu'on renforce de plus en plus, jusqu'à ce que le flux devienne entièrement embrouillé. Le but recherché est d'éveiller l'intérêt de l'utilisateur pour le flux vidéo, mais en lui enlevant les droits de visualisation si ce dernier ne les a pas achetés. Une réalisation de cette application est d'embrouiller le flux vidéo avec un et/ou des algorithmes donnés en modifiant progressivement les paramètres d' embrouillage pendant une durée de temps déterminée de manière à augmenter le désagrément, jusqu'à arriver à un flux complètement embrouillé. On réalise généralement un embrouillage adaptatif en fonction du contenu, des caractéristiques, de la structure et de la composition du flux numérique défini par un standard donné.An adaptation of the scrambling parameters is also applied as a function of the granular scalability characterizing certain video streams. We define the notion “granular scalability” from the English expression “granular scalability” used in the MPEG-4 standard which characterizes an encoder capable of encoding or a decoder capable of decoding an ordered set of bit streams so as to produce or reconstruct a multi-layered sequence. We define granularity as the amount of information that can be transmitted per layer of a system characterized by any scalability, the system is then also granular. An adaptation is also applied as a function of the bit rate in number of bits per second (bits / s) of the video stream, whether constant or variable. For example, effective scrambling for a rate of 2 Mbits / s is less effective for much higher rates. For certain more complex flows (such as those of the MPEG-4 type), adaptive scrambling is applied according to the types of objects, the profile ("profile"), the level ("level"), designating the complexity and the options used when building the video stream. An adaptation is applied as a function of the number of frames per second of the video stream. For certain flows characterized by a temporal scalability, one applies an adaptive scrambling according to the number of frames per second variable. Progressive scrambling is also applied, so that the user begins to watch the unscrambled video stream. Then, we start with a light scrambling which we reinforce more and more, until the flow becomes entirely tangled. The aim is to arouse the user's interest in the video stream, but by removing their viewing rights if the latter has not purchased them. One embodiment of this application is to scramble the video stream with one and / or given algorithms by gradually modifying the scrambling parameters over a determined period of time so as to increase the inconvenience, until arriving at a completely scrambled stream. . Adaptive scrambling is generally carried out as a function of the content, characteristics, structure and composition of the digital stream defined by a given standard.
On réalise également un embrouillage avec une génération aléatoire des combinaisons paramétriques à appliquer pour l'embrouillage du flux vidéo. De cette manière, on assure une protection robuste et difficilement attaquable, ne pouvant pas être piratée par une personne mal intentionnée. L'inconvénient qui pourrait se présenter est que, suite à cette génération paramétrique aléatoire, certaines séquences peuvent ne pas être suffisamment embrouillées, dû au fait que le générateur aléatoire ne tient pas compte du contenu des flux.Scrambling is also carried out with a random generation of the parametric combinations to be applied for scrambling the video stream. In this way, a robust and difficult to attack protection is provided, which cannot be hacked by a malicious person. The drawback which could arise is that, following this random parametric generation, certain sequences may not be sufficiently scrambled, due to the fact that the random generator does not take account of the content of the streams.
On applique également une adaptation des paramètres et algorithmes d' embrouillage en fonction du profil du destinataire, en fonction du comportement du destinataire pendant la connexion au serveur (par exemple la régularité et l'acceptation des paiements), en fonction de ses habitudes (par exemple temps, heure de connexion), en fonction de ses caractéristiques (par exemple âge, sexe, religion, communauté), ou en fonction de données communiquées par un tiers (par exemple appartenance à des associations ou figurant sur des bases de données de consommateurs ) . On applique également une adaptation des paramètres et algorithmes d' embrouillage en fonction d'événements externes, par exemple, heure de diffusion, taux d'audience, événement sociaux-politiques, perturbations durant la diffusion.We also apply an adaptation of the scrambling parameters and algorithms according to the recipient's profile, according to the recipient's behavior during connection to the server (for example regularity and acceptance of payments), according to their habits (for example time, time of connection), according to its characteristics (for example age, sex, religion, community), or according to data communicated by a third party (for example membership of associations or appearing in consumer databases). We also apply an adaptation of the scrambling parameters and algorithms according to external events, for example, broadcast time, audience rate, social-political event, disturbances during the broadcast.
L'invention concerne dans son acception la plus générale un procédé pour la distribution de séquences vidéos numériques selon un format de flux nominal constitués par une succession de trames dites « frames » comprenant chacune au moins un bloc regroupant une pluralité de coefficients correspondant à des éléments visuels simples codés numériquement, le procédé comportant une étape de modification d'au moins un bloc du flux originel caractérisé en ce que ladite étape de modification agit de façon adaptative sur ledit flux originel en fonction d'une partie au moins des caractéristiques représentatives de la structure, du contenu et des paramètres du flux vidéo originel, du profil du destinataire, et d'événements externes. De préférence, l'étape de modification consiste à remplacer une partie desdits coefficients pour produire d'une part un flux vidéo principal au format nominal et d'autre part une information complémentaire de modification permettant la reconstruction du flux originel par un décodeur de l'équipement destinataire, la portée des modifications étant variable et déterminée par lesdites caractéristiques représentatives.The invention relates in its most general sense to a method for the distribution of digital video sequences according to a nominal flow format constituted by a succession of so-called "frames" each comprising at least one block grouping a plurality of coefficients corresponding to elements digitally coded simple visuals, the method comprising a step of modifying at least one block of the original flow characterized in that said modification step acts adaptively on said original flow as a function of at least some of the characteristics representative of the structure, content and parameters of the original video stream, the recipient's profile, and external events. Preferably, the modification step consists in replacing part of said coefficients to produce on the one hand a main video stream in nominal format and on the other hand complementary modification information allowing the reconstruction of the original stream by a decoder of the recipient equipment, the scope of the modifications being variable and determined by said representative characteristics.
Selon une variante, le flux principal modifié est enregistré sur l'équipement destinataire préalablement à la transmission de l'information complémentaire sur l'équipement destinataire.According to a variant, the modified main stream is recorded on the destination equipment prior to the transmission of additional information on the recipient equipment.
Selon une autre variante, le flux principal modifié et l'information complémentaire sont transmis ensemble en temps réel.According to another variant, the modified main stream and the additional information are transmitted together in real time.
Avantageusement, ladite information complémentaire de modification comprend au moins une routine numérique apte à exécuter une fonction.Advantageously, said additional modification information comprises at least one digital routine capable of executing a function.
Selon un mode de mise en œuvre particulier, ladite information complémentaire de modification est subdivisée en au moins deux sous-parties.According to a particular mode of implementation, said additional modification information is subdivided into at least two sub-parts.
Selon une variante, lesdites sous-parties de l'information complémentaire de modification peuvent être distribuées par différents médias . Selon une autre variante, lesdites sous- parties de l'information complémentaire de modification peuvent être distribuées par le même média.Alternatively, said sub-parts of the additional modification information may be distributed by different media. According to another variant, said sub-parts of the additional modification information can be distributed by the same medium.
Selon un mode de mise en œuvre particulier, l'information complémentaire est transmise sur un vecteur physique.According to a particular mode of implementation, the additional information is transmitted on a physical vector.
Selon une variante, l'information complémentaire est transmise en ligne.According to a variant, the additional information is transmitted online.
Selon un mode de mise en œuvre particulier, lesdites images numériques utilisent les technologies à base d'ondelettes.According to a particular mode of implementation, said digital images use wavelet-based technologies.
De préférence, les flux vidéo sont organisés en trames constituées de blocs correspondant à au moins un plan I, un plan P correspondant aux différences entre une image appelée P, au moins une autre image I ou P, aussi pouvant contenir au moins un plan B correspondant aux différences entre deux images P, et des plans S.Preferably, the video streams are organized in frames consisting of blocks corresponding to at least one plane I, a plane P corresponding to the differences between an image called P, at least one other image I or P, also being able to contain at least one plane B corresponding to the differences between two images P, and planes S.
Avantageusement, lesdites images I, P, B et S sont modifiées de manière différenciée en fonction de leur type, notamment I, P, B ou S. Selon une variante, les images I, P, B et S sont modifiées de manière différenciée en fonction des caractéristiques du flux vidéo en termes de structure des groupes d'images GOPs, et des proportions entre les quantités d'images I, P, B présentes dans les flux vidéos, ces derniers étant caractérisés par un nombre de plans par seconde constant ou variable ou caractérisé par une scalabilité temporelle.Advantageously, said images I, P, B and S are modified in a differentiated manner according to their type, in particular I, P, B or S. According to a variant, the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the video stream in terms of structure of the groups of images GOPs, and of the proportions between the quantities of images I, P, B present in video streams, the latter being characterized by a constant or variable number of shots per second or characterized by temporal scalability.
Selon une autre variante, les images I, P, B et S sont modifiées de manière différenciée en fonction du nombre de plans (trames) par seconde constant ou variable pour les flux caractérisés par la scalabilité temporelle.According to another variant, the images I, P, B and S are modified in a differentiated manner as a function of the number of planes (frames) per second constant or variable for the flows characterized by temporal scalability.
Selon un autre mode de mise en œuvre particulier, les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des scènes contenues dans le flux en termes de plans fixes, statiques ou dynamiques et/ou des formes visuelle contenues, et/ou en fonction de la scalabilité granulaire.According to another particular mode of implementation, the images I, P, B and S, are modified in a differentiated manner as a function of the characteristics of the scenes contained in the flow in terms of fixed, static or dynamic shots and / or visual forms contained, and / or as a function of granular scalability.
Avantageusement, les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des flux en terme de la taille des plansAdvantageously, the images I, P, B and S, are modified in a differentiated manner as a function of the characteristics of the flows in terms of the size of the planes
(en nombre de pixels), qu'elle soit constante ou variable pour les flux caractérisés par la scalabilité spatiale.(in number of pixels), whether constant or variable for flows characterized by spatial scalability.
De préférence, les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des flux en terme de débit en bits par seconde du flux vidéo.Preferably, the images I, P, B and S are modified in a differentiated manner as a function of the characteristics of the streams in terms of bit rate per second of the video stream.
Avantageusement, les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des flux vidéos en terme de composition en objets, profils et niveaux.Advantageously, the images I, P, B and S, are modified in a differentiated manner as a function of the characteristics of the video streams in terms of composition in objects, profiles and levels.
De préférence, les images I, P, B et S sont modifiées d'une manière progressive augmentant l'effet de dégradation jusqu'à l'embrouillage complet du flux vidéo. Selon une variante, les images I, P, B et S sont modifiées avec une génération aléatoire des paramètres et configurations d'embrouillage.Preferably, the images I, P, B and S are modified in a progressive manner increasing the degradation effect until the video stream is completely scrambled. According to a variant, the images I, P, B and S are modified with a random generation of the scrambling parameters and configurations.
Selon une autre variante, l'embrouillage est adaptatif en fonction du contenu, des caractéristiques, de la structure et de la composition du flux vidéo, dont le format de flux nominal est défini par la norme MPEG-1 ouAccording to another variant, the scrambling is adaptive as a function of the content, characteristics, structure and composition of the video stream, the nominal stream format of which is defined by the MPEG-1 standard or
MPEG-2 ou MPEG-4 ou autres.MPEG-2 or MPEG-4 or others.
Selon un mode de mise en œuvre particulier, le procédé comporte une étape préalable de conversion analogique/numérique sous un format structuré, le procédé étant appliqué à un signal vidéo analogique.According to a particular mode of implementation, the method comprises a preliminary step of analog / digital conversion in a structured format, the method being applied to an analog video signal.
De préférence, le flux vidéo reconstitué à partir du flux principal modifié et de l'information complémentaire est strictement identique au flux originel.Preferably, the video stream reconstituted from the modified main stream and additional information is strictly identical to the original stream.
La présente invention se rapporte également à un système pour la distribution de séquences vidéos comportant un serveur vidéo comprenant des moyens pour diffuser un flux modifié conformément à l'un quelconque des procédés précédents, et une pluralité d'équipements munis d'un circuit d' embrouillage, caractérisé en ce que le serveur comprend en outre un moyen d'enregistrement du profil numérique de chaque destinataire et un moyen d'asservissement des moyens de modification en fonction de variables d'entrée correspondant à une partie au moins des caractéristiques représentatives de la structure, du contenu et des paramètres du flux vidéo originel, du profil du destinataire, et d'événements externes.The present invention also relates to a system for the distribution of video sequences comprising a video server comprising means for broadcasting a stream modified in accordance with any one of the preceding methods, and a plurality of equipment provided with a circuit scrambling, characterized in that the server further comprises means for recording the digital profile of each recipient and means for controlling the modification means as a function of input variables corresponding to at least some of the characteristics representative of the structure, content and parameters of the original video stream, the recipient's profile, and external events.
On comprendra mieux 1 ' invention à 1 ' aide de la description, faite ci-après à titre purement explicatif, d'un mode de réalisation de l'invention, en référence à la figure annexée :The invention will be better understood with the aid of the description, given below for purely explanatory purposes, of an embodiment of the invention, with reference to the appended figure:
- la figure 1 illustre un mode de réalisation particulier du système client-serveur selon l'invention. Considérons un exemple de réalisation . Sur le dessin en annexe , la figure 1 représente un mode de réalisation particulier du système client-serveur conforme à- Figure 1 illustrates a particular embodiment of the client-server system according to the invention. Let us consider an example of realization. In the accompanying drawing, FIG. 1 represents a particular embodiment of the client-server system in accordance with
1 ' invention . Le flux vidéo de type MPEG-2 que l'on souhaite sécuriser (1) est passé à un système d'analyse (121) et d' embrouillage (122) qui va générer un flux principal modifié et une information complémentaire en sortie.1 invention. The MPEG-2 video stream that one wishes to secure (1) is passed to an analysis (121) and scrambling (122) system which will generate a modified main stream and additional information at the output.
Le flux d'origine (1) peut être directement sous forme numérique (10) ou sous forme analogique (11). Dans ce dernier cas, le flux analogique (11) est converti par un codeur non représenté en un format numérique (10). Dans la suite du texte, nous noterons (1) le flux numérique vidéo d'entrée. Un premier flux (124) au format MPEG-2, de format identique au flux numérique d'entrée (1) en dehors de ce que certains des coefficients, valeurs et/ou vecteurs ont été modifiés, est placé dans une mémoire tampon de sortie (125). L'information complémentaire (123), de format quelconque, contient les références des parties des échantillons vidéos qui ont été modifiées et est placée dans le tampon (126). En fonction des caractéristiques du flux d'entrée (1) , le système d'analyse (121) et d' embrouillage (122) décide quel embrouillage adaptatif appliquer et quels paramètres du flux modifier et aussi en fonction des droits du client, de quelle manière appliquer les modifications, par exemple progressive ou pas.The original stream (1) can be directly in digital form (10) or in analog form (11). In the latter case, the analog stream (11) is converted by an encoder not shown in a digital format (10). In the following text, we will note (1) the digital input video stream. A first stream (124) in MPEG-2 format, of format identical to the digital input stream (1) apart from the fact that some of the coefficients, values and / or vectors have been modified, is placed in an output buffer memory (125). The complementary information (123), in any format, contains the references of the parts of the video samples which have been modified and is placed in the buffer (126). Depending on the characteristics of the input flow (1), the analysis (121) and scrambling (122) system decides which adaptive scrambling to apply and which parameters of the flow to modify and also according to the rights of the client, from which way to apply the modifications, for example progressive or not.
Le flux MPEG-2 (125) est ensuite transmis, via un réseau haut débit (4) de type hertzien, câble, satellite, etc., au client (8), et plus précisément dans sa mémoire (81) de type RAM, ROM, disque dur. Lorsque le destinataire (8) fait la demande de visualiser une séquence vidéo présente dans sa mémoire (81), deux éventualités sont possibles : - soit le destinataire (8) ne possède pas les droits nécessaires pour visualiser la séquence vidéo. Dans ce cas, le flux (125) généré par le système de brouillage (122) présent dans sa mémoire (81) est passé au système de synthèse (82), qui ne le modifie pas et le transmet à l'identique à un lecteur vidéo classique (83) et son contenu, fortement dégradé visuellement, est affiché par le player (83) sur un écran (9).The MPEG-2 stream (125) is then transmitted, via a broadband network (4) of the radio type, cable, satellite, etc., to the client (8), and more precisely in its memory (81) of the RAM type, ROM, hard drive. When the recipient (8) requests to view a video sequence present in his memory (81), two possibilities are possible: - either the recipient (8) does not have the necessary rights to view the video sequence. In this case, the stream (125) generated by the scrambling system (122) present in its memory (81) is passed to the synthesis system (82), which does not modify it and transmits it identically to a reader. classic video (83) and its content, strongly degraded visually, is displayed by the player (83) on a screen (9).
- soit, le destinataire (8) possède les droits pour regarder la séquence vidéo. En fonction des droits du destinataire, le serveur 12 transmet l'information complémentaire (126) appropriée par la liaison (6), correspondant au type d' embrouillage effectué. Dans ce cas, le système de synthèse fait une demande de visualisation au serveur (12) contenant l'information nécessaire (126) à la récupération de la séquence vidéo originale (1). Le serveur (12) envoie alors par la liaison (6) via des réseaux de télécommunication type ligne téléphonique analogique ou numérique, DSL (Digital Subscriber Line), BLR (Boucle Locale Radio), DAB (Digital Audio Broadcasting) ou de télécommunications mobiles numériques (GSM, GPRS, UMTS), l'information complémentaire (126) permettant la reconstitution de la séquence vidéo de façon à ce que le client (8) puisse visualiser et/ou stocker la séquence vidéo. Le système de synthèse (82) procède alors au désembrouillage de la vidéo par la reconstruction du flux d'origine en combinant le flux principal modifié (125) et l'information complémentaire (126). Le flux vidéo ainsi obtenu en sortie du système de synthèse (82) est alors transmis au lecteur vidéo classique (83) et le film vidéo originel est affiché à l'écran (9) . - Either, the recipient (8) has the rights to watch the video sequence. Depending on the recipient's rights, the server 12 transmits the appropriate additional information (126) via the link (6), corresponding to the type of scrambling carried out. In this case, the synthesis system makes a display request to the server (12) containing the information necessary (126) for recovering the original video sequence (1). The server (12) then sends via the link (6) via telecommunication networks such as analog or digital telephone line, DSL (Digital Subscriber Line), BLR (Local Radio Loop), DAB (Digital Audio Broadcasting) or digital mobile telecommunications. (GSM, GPRS, UMTS), the additional information (126) allowing the reconstruction of the video sequence so that the client (8) can view and / or store the video sequence. The synthesis system (82) then proceeds to descramble the video by reconstructing the original stream by combining the modified main stream (125) and the additional information (126). The video stream thus obtained at the output of the synthesis system (82) is then transmitted to the conventional video player (83) and the original video film is displayed on the screen (9).

Claims

REVENDICATIONS
1. Procédé pour la distribution de séquences vidéos numériques selon un format de flux nominal constitués par une succession de trames comprenant chacune au moins un bloc regroupant une pluralité de coefficients correspondant à des éléments visuels simples codés numériquement, le procédé comportant une étape de modification d'au moins un bloc du flux originel caractérisé en ce que ladite étape de modification agit de façon adaptative sur ledit flux originel en fonction d'une partie au moins des caractéristiques représentatives de la structure, du contenu et des paramètres du flux vidéo originel, du profil du destinataire, d'événements externes, et en ce que l'étape de modification consiste à remplacer une partie desdits coefficients pour produire d'une part un flux vidéo principal modifié au format nominal et d'autre part une information complémentaire de modification permettant la reconstruction du flux originel par un décodeur de l'équipement destinataire, la portée des modifications étant variable et déterminée par lesdites caractéristiques représentatives, et en ce que le flux principal modifié et l'information complémentaire sont transmis à l'utilisateur par voie séparée.1. Method for the distribution of digital video sequences according to a nominal flow format constituted by a succession of frames each comprising at least one block grouping a plurality of coefficients corresponding to simple visual elements digitally coded, the method comprising a step of modifying '' at least one block of the original stream characterized in that the said modification step acts adaptively on the said original stream as a function of at least some of the characteristics representative of the structure, the content and the parameters of the original video stream, of the profile of the recipient, of external events, and in that the modification step consists in replacing part of said coefficients to produce on the one hand a main video stream modified in nominal format and on the other hand additional modification information allowing reconstruction of the original flow using a destinata equipment decoder ire, the scope of the modifications being variable and determined by said representative characteristics, and in that the modified main stream and the additional information are transmitted to the user by separate means.
2. Procédé pour la distribution de séquences vidéos numériques selon la revendication 1, caractérisé en ce que ladite information complémentaire de modification comprend au moins une routine numérique apte à exécuter une fonction.2. Method for the distribution of digital video sequences according to claim 1, characterized in that said additional modification information comprises at least one digital routine capable of executing a function.
3. Procédé pour la distribution de séquences vidéos numériques selon les revendications 1 et 2, caractérisé en ce que ladite information complémentaire de modification est subdivisée en au moins deux sous-parties. 3. Method for the distribution of digital video sequences according to claims 1 and 2, characterized in that said additional modification information is subdivided into at least two sub-parts.
4. Procédé pour la distribution de séquences vidéos numériques selon la revendication 3, caractérisé en ce que lesdites sous-parties de l'information complémentaire de modification peuvent être distribuées par différents médias .4. Method for the distribution of digital video sequences according to claim 3, characterized in that said sub-parts of the additional modification information can be distributed by different media.
5. Procédé pour la distribution de séquences vidéos numériques selon la revendication 3, caractérisé en ce que lesdites sous-parties de l'information complémentaire de modification peuvent être distribuées par le même média.5. Method for the distribution of digital video sequences according to claim 3, characterized in that said sub-parts of the additional modification information can be distributed by the same media.
6. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications6. Method for the distribution of digital video sequences according to at least one of the claims
1 à 5, caractérisé en ce que l'information complémentaire est transmise sur un vecteur physique.1 to 5, characterized in that the additional information is transmitted on a physical vector.
7. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications7. Method for the distribution of digital video sequences according to at least one of the claims
1 à 5, caractérisé en ce que l'information complémentaire est transmise en ligne.1 to 5, characterized in that the additional information is transmitted online.
8. Procédé pour la distribution de séquences vidéos numériques selon l'une des revendications précédentes, caractérisé en ce que lesdites images numériques utilisent les technologies à base d'ondelettes.8. Method for the distribution of digital video sequences according to one of the preceding claims, characterized in that said digital images use wavelet-based technologies.
9. Procédé pour la distribution de séquences vidéos numériques selon la revendication 1, caractérisé en ce que les flux vidéo sont organisés en trames constituées de blocs correspondant à au moins un plan I, un plan P correspondant aux différences entre une image appelée P, au moins une autre image I ou P, pouvant contenir au moins un plan B correspondant aux différences entre deux images P ou des plans S correspondant à une image statique.9. Method for the distribution of digital video sequences according to claim 1, characterized in that the video streams are organized in frames consisting of blocks corresponding to at least one plane I, a plane P corresponding to the differences between an image called P, at at least one other I or P image, which may contain at least a plane B corresponding to the differences between two images P or planes S corresponding to a static image.
10. Procédé pour la distribution de séquences vidéos numériques selon la revendication 9, caractérisé en ce que lesdites images I, P, B et S sont modifiées de manière différenciée en fonction de leur type, notamment10. Method for the distribution of digital video sequences according to claim 9, characterized in that said images I, P, B and S are modified in a differentiated manner according to their type, in particular
I, P, B ou S.I, P, B or S.
11. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 10, caractérisé en ce que les images I, P, B et S sont modifiées de manière différenciée en fonction des caractéristiques du flux vidéo en termes de structure des groupes d'images GOPs, et des proportions entre les quantités d'images I, P, B, S présentes dans les flux vidéos, ces derniers étant caractérisés par un nombre de plans par seconde constant ou variable.11. Method for the distribution of digital video sequences according to at least one of claims 9 to 10, characterized in that the images I, P, B and S are modified in a differentiated manner according to the characteristics of the video stream in terms of structure of the groups of images GOPs, and of the proportions between the quantities of images I, P, B, S present in the video streams, the latter being characterized by a number of shots per second constant or variable.
12. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 11, caractérisé en ce que les images I, P et B sont modifiées de manière différenciée en fonction du nombre de plans (trames) par seconde constant ou variable pour les flux caractérisés par la scalabilité temporelle.12. Method for the distribution of digital video sequences according to at least one of claims 9 to 11, characterized in that the images I, P and B are modified in a differentiated manner as a function of the number of planes (frames) per constant second or variable for flows characterized by temporal scalability.
13. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 12, caractérisé en ce que les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des scènes contenues dans le flux en termes de plans fixes , statiques ou dynamiques et/ou des formes visuelles contenues. 13. Method for the distribution of digital video sequences according to at least one of claims 9 to 12, characterized in that the images I, P, B and S, are modified in a differentiated manner as a function of the characteristics of the scenes contained in the flow in terms of fixed, static or dynamic planes and / or contained visual forms.
14. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 13, caractérisé en ce que les images I, P, B et S, sont modifiées de manière différenciée en fonction de leur scalabilité granulaire.14. Method for the distribution of digital video sequences according to at least one of claims 9 to 13, characterized in that the images I, P, B and S, are modified in a differentiated manner as a function of their granular scalability.
15. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 14, caractérisé en ce que les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des flux en termes de la taille de ses plans (en nombre de pixels), qu'elle soit constante ou variable pour les flux caractérisés par la scalabilité spatiale.15. Method for the distribution of digital video sequences according to at least one of claims 9 to 14, characterized in that the images I, P, B and S, are modified in a differentiated manner as a function of the characteristics of the streams in terms of the size of its planes (in number of pixels), whether constant or variable for flows characterized by spatial scalability.
16. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 15, caractérisé en ce que les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des flux en termes de débit en bits par seconde du flux vidéo.16. Method for the distribution of digital video sequences according to at least one of claims 9 to 15, characterized in that the images I, P, B and S, are modified in a differentiated manner as a function of the characteristics of the flows in terms of bit rate per second of the video stream.
17. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 16, caractérisé en ce que les images I, P, B et S, sont modifiées de manière différenciée en fonction des caractéristiques des flux vidéos en termes de composition en objets, profils et niveaux.17. Method for the distribution of digital video sequences according to at least one of claims 9 to 16, characterized in that the images I, P, B and S, are modified in a differentiated manner according to the characteristics of the video streams in terms of composition in objects, profiles and levels.
18. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 17, caractérisé en ce que les images I, P, B et S, sont modifiées d'une manière progressive augmentant l'effet de dégradation jusqu'à l'embrouillage complet du flux vidéo. 18. Method for the distribution of digital video sequences according to at least one of claims 9 to 17, characterized in that the images I, P, B and S, are modified in a progressive manner increasing the degradation effect up to 'at full scrambling of the video stream.
19. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications 9 à 18, caractérisé en ce que les images I, P, B et S sont modifiées avec une génération aléatoire des paramètres et configurations d'embrouillage.19. Method for the distribution of digital video sequences according to at least one of claims 9 to 18, characterized in that the images I, P, B and S are modified with a random generation of the scrambling parameters and configurations.
20. Procédé pour la distribution de séquences vidéos numériques selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comporte une étape préalable de conversion analogique/numérique sous un format structuré, le procédé étant appliqué à un signal vidéo analogique.20. Method for the distribution of digital video sequences according to any one of the preceding claims, characterized in that it comprises a preliminary step of analog / digital conversion in a structured format, the method being applied to an analog video signal.
21. Procédé pour la distribution de séquences vidéos numériques selon l'une au moins des revendications précédentes, caractérisé en ce que le flux vidéo reconstitué à partir du flux principal modifié et de l'information complémentaire est strictement identique au flux originel.21. Method for the distribution of digital video sequences according to at least one of the preceding claims, characterized in that the video stream reconstructed from the modified main stream and additional information is strictly identical to the original stream.
22. Système pour la distribution de séquences vidéos numériques comportant un serveur vidéo comprenant des moyens pour diffuser un flux modifié conformément à l'une quelconque des revendications précédentes, et une pluralité d'équipements munis d'un circuit d' embrouillage, caractérisé en ce que le serveur comprend en outre un moyen d'enregistrement du profil numérique de chaque destinataire et un moyen d'asservissement des moyens de modification en fonction de variables d'entrée correspondant à une partie au moins des caractéristiques représentatives de la structure, du contenu et des paramètres du flux vidéo originel, du profil du destinataire, et d'événements externes. 22. System for the distribution of digital video sequences comprising a video server comprising means for broadcasting a modified stream according to any one of the preceding claims, and a plurality of equipment provided with a scrambling circuit, characterized in that that the server further comprises a means for recording the digital profile of each recipient and a means for controlling the modification means as a function of input variables corresponding to at least some of the characteristics representative of the structure, of the content and settings for the original video stream, the recipient's profile, and external events.
EP03798956A 2002-10-03 2003-10-03 Adaptive and progressive video stream scrambling Ceased EP1559270A1 (en)

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FR0212269A FR2845556B1 (en) 2002-10-03 2002-10-03 ADAPTIVE AND PROGRESSIVE STRIPPING OF VIDEO STREAMS
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