Patent Application
20080097919
In the following the present invention will be discussed in more detail by taking reference to the accompanying Figures.
a is a table Tab. 1a, which shows a generic preferred coding of the set of usage properties, parameters, and arguments for the content management usage properties.
b is a table Tab. 1b, which shows a generic preferred coding of the set of usage properties, parameters, and arguments for the propagation restriction usage properties.
a is a table Tab. 2a which shows a syntax for each usage state information property and the respective usage parameters and arguments of the content management usage properties.
b is a table Tab. 2b which shows a syntax for each usage state information property and the respective usage parameters and arguments of the propagation restriction usage properties.
Protected audio-video content can reach the consumer via many different channels, each having its own kind of protection system and content usage rules.
Area A1 is the authorized domain of a user or household, to which devices including the functionality of the CPCM system may be associated.
Area A2 is the immediate vicinity around any device including the functionality of the CPCM system, or any content item within the CPCM system, hence area A2 is referred to as the local environment.
Area A2a corresponds to the set of devices including the functionality of the CPCM system that are in the immediate vicinity and that belong to the same authorized domain, hence area A2a is referred to as the localized authorized domain. Area A2a is a subset of both area A1, the authorized domain, and area A2, the local environment.
Area A2b corresponds to the set of devices including the functionality of the CPCM system that are in the immediate vicinity but that either belong to a different authorized domain or that belong to no authorized domain, or are not equipped with the authorized domain membership part of the CPCM system functionality.
Area A1a corresponds to the set of devices including the functionality of the CPCM system in the authorized domain which are located within said geographic area A3, for example at the user's or household's main residence in the home region.
Area A1b corresponds to the set of devices including the functionality of the CPCM system in the authorized domain which are located outside said geographic area A3, for example at the user's or household's holiday or second home in a different region.
Area A3 corresponds to any geographic area or region within which it may be necessary to constrain the propagation of certain types of content.
Area A1, the authorized domain, is inherently orthogonal and managed independently to area A2, the local environment, and area A3, the geographic area. Area A3 is inherently a subset of area A3.
Due to the nature and inter-relationship of these different classes of area, it is feasible to define the hierarchy of outer and inner content propagation restrictions as described previously and the corresponding flexibility of specifying content usage rights information CURI and/or the respective usage state information USI with respect to these different areas.
In the realm of DRM, several Rights Expression Languages (REL) are established, even standardized, in the prior art, e.g. XrML [6], ODRL [7]. In a web-based computing environment it is advantageous to deploy such RELs based on XML, as much of the processing tools or software is generally already built into the devices (networked PC, browser). Also, the relatively inefficient data formats of XML-based RELs are not an issue when a single item of content is being delivered to a consumer, for example within an internet DRM system.
In a broadcast environment, however, many, even hundreds of services are available to the consumer in parallel. It is desirable to inform the user, via his receiving equipment, of any eventual content usage restrictions, or rights associated with content items, for currently available content, or scheduled future content in advance, for example as icons accompanying services generally listed in an on-screen EPG.
To deploy such an XML-based REL in a broadcast environment has the following disadvantages:
Therefore it is the goal of the present invention to provide a method for carrying such USI in broadcast content streams in an efficient manner, and one more suitable for all types of broadcast receiver. This method can also be used to carry such USI within a CPCM system for the consumer environment, i.e. among AV storage, processing, and rendering devices in the home network.
An additional advantage of the present invention is that the method of embedding USI in an item of content provides a convenient tool for the interoperable exchange of content between different DRM or content protection systems. This is due to the fact that no additional data is required to be passed between such systems, apart from the item of content itself, which contains all necessary information (USI and auxiliary data) pertaining to its allowed usage in the compliant domain.
The method is summarized as providing:
MPEG IPMP [1] is an ISO/IEC Standard defining a DRM framework for MPEG content. It includes the Extensible Rights Markup Language (XrML) [6] as the Rights Expression Language to provide the complete set of possible Usage Rules (UR) for IPMP content. However, this standard is too feature-rich and complicated to be used for the practical realization of an interoperable DRM framework encompassing all classes of consumer audio-visual devices. Indeed, an XML-based language is not suitable for the complete spectrum of consumer entertainment devices, due to the memory and processing resources necessary to work with it.
The Open Digital Rights Language (ODRL) [7] does indeed provide a simpler set of UR than XrML, but is still much too powerful for a common baseline approach for CPCM in the consumer environment.
Both XrML and ODRL are providing full DRM rights expression tools, covering all types of media, and commercial transactions and billing, for example. A CPCM system does not require such functionality and can omit such features from its pre-defined set of USI.
The TV-Anytime Forum (TVAF) recently published a specification for Rights Management and Protection for broadcast content [4]. RMPI and RMPI-MB are applicable to the same realm as the current invention, but the TVA/RMPI is not fully suitable for horizontal market interoperable CPCM frameworks and does not include all necessary tools required for such. Apart from that, some aspects also imply a greater burden of implementation for manufacturers of compliant consumer equipment. The present invention presents an alternative scheme to TVA RMPI, relying more on a fixed CPCM framework and regime for content protection management, thus providing a simpler and clearer framework for the consumer.
The format suitable for broadcast and home network CPCM systems is some form of structured binary coded data that can be embedded repeatedly within the content data file or stream. The pre-defined structure and coding means that many of the often extensive header tags necessary with XML-based usage rule coding schemes can be omitted. Each coded usage rule setting that is translated then becomes a pre-defined 8-bit binary value, instead of text-form delimiters. Of course, eventual argument fields might not be able to be compressed.
Process 1 yields the AV content to be managed and protected by the CPCM System. In the prior art, this content can have a content identifier obtained by process 2 and content usage rights associated with it and obtained by process 3, but often provided separately from the content item itself, in a separate file, or stored in a database.
In process 4 the usage rights converter involves the parsing and generation of the equivalent usage rights according to the CPCM System. Its output is the binary coded set of data corresponding to the CPCM System and broadcast friendly usage rights or USI data according to process 6. The USI data can also be generated directly by a usage rights generator tool or process 5.
Process 7, the auxiliary data embedder inserts the CPCM content usage rights, or USI, into the CPCM compliant content item CI stored data file according to process 8, or the CPCM compliant content stream according to process 9, depending on the application at hand. One feature of the invention is that such USI data is repeated regularly within the CPCM Content Item or CPCM compliant content stream, to facilitate the quick and correct interpretation of the content usage rights when the receiving device of such content performs random access to the content, for example during live broadcast while hopping channels on the broadcast receiver.
As is common with digital broadcast systems, many such individual content streams, or services, can be multiplexed (process 11) to form a content stream containing several services. The service multiplexer (process 10) collects the content identifiers (process 13) USI data (process 12) for all services to be carried in the multiplex. It can also collect this information relating to content scheduled in the future, in order to provide advance information about the usage rights in advance. Process 14 yields the resulting multiplex of content services including all USI for the services contained and scheduled content.
Each usage right, usually encoded with a “tag” section, is interpreted, and the equivalent usage right is generated on the basis of pre-defined mappings from the input format. Usage rights for which no mapping is defined in the CPCM USI are ignored.
When all input usage rights have been parsed and converted, the output CPCM usage rights data, or USI, is generated. This is input to the Auxiliary Data Embedder, which combines the USI with the content as described previously.
The Auxiliary Data Embedder could also consist of a multiplexer, which combines several content items, or streams, into a multiplexed content stream, as commonly used in broadcast systems, for example DVB.
The Auxiliary Data Embedder could also embed USI about content items available in the future.
The USI could form another component of already defined auxiliary data defined in the broadcast system, for example the Service Information [8] in the case of DVB. Such a preferred embodiment is described later.
One advantage of the present invention becomes evident when the decoding process in the consumer environment is considered, both at the point of first acquisition of CPCM complaint protected content, and after storage (if allowed by the USI) and subsequent retrieval by any rendering device in the home network. Because the USI has already been converted to the CPCM System compliant format, no renewed interaction with the originating DRM or CA system is necessary to establish the usage rights for that content. All CPCM devices accessing the content are able to process the content and abide by the usage rules because they are stored and embedded within the content file or stream in a format easily processable by those devices, in the DVB example, as an additional descriptor within the service's or content item's associated SI.
Another feature of the invention is the display of icons indicating the allowed or disallowed functionality with respect to the received content on the rendering device's graphical user interface, allowing the user to know in advance how he is able to use that content.
A typical feature of an EPG function is to show information about programming content, or events, in the future. In the same way, the accompanying USI in the SI can be used to indicate to the user his available options for that content item available in the future, alternatively the user interface could blank out functionality that is apparently disallowed by the USI.
This section provides a definition of the set of Usage Rules (UR) for audio-visual content in the consumer environment, and methods of communication of this information with the associated content, both prior to content reception in a consumer's domain (in the delivery channel), and for the subsequent life of the content in the domain (on all devices which can use the content, networked devices in the home(s), also in the consumer's private vehicle(s) and on mobile handheld devices.
URs are communicated within the CPCM Framework by encoding them in a pre-defined scheme. Such data is referred to as “Usage State Information” (USI).
The complete set of Usage Rules for a CPCM Framework is defined here. The URs are defined as a set of Properties applied to an item of content. This set is deemed to be complete in terms of the minimum set of necessary controls with audio-visual content functionality in the consumer environment.
According to the invention, there are two kinds of UR Property, and hence derived Usage State Information (USI)—Mandatory and Assertive.
Mandatory USI: Any item of CPCM content must always have one of the Mandatory USI field's states applied to it.
Assertive USI: The presence of Assertive USI implies that the associated restriction/concession is being imposed/granted. If a particular Assertive USI field is not present with any item of content then that restriction/concession is not imposed/granted.
Assertive USI is orthogonal to the Mandatory USI, i.e. each Assertive USI field can be applied with any of the Mandatory USI field states.
In the case of content Copy, the generated new instance of content generally inherits the non-Copy USI of the original instance.
Each UR Property is described in the following sub-sections.
A simple model for copy control USI is already largely established in the prior art. It is adopted as forming one component of the CPCM Framework UR. This provides the options for marking content in one of five states:
A Copy action on content bearing either the C1 or the C1G state produces a new instance of that content bearing the CNM state.
In the CPCM Framework, the Copy Control USI Property is Mandatory USI.
Some content providers maintain the commercial requirement to be able to restrict the number of concurrent renderings of an item of content, e.g. the number of display devices rendering that content in the home. Thus the CPCM Framework includes this ability in the USI.
In the CPCM Framework, the USI Restrict Concurrent Rendering (RCR) is optional USI, and is always augmented by the maximum count of concurrent renderings allowed. If the RCR Property is not present in the USI then that content is viewable on any number of rendering devices (but also subject to the eventual propagation restriction specified in the USI, alternatively up to a generally valid maximum number of concurrent renderings which might be specified).
Alternatively, the RCR Property could have a parameter defined such as “restriction not asserted”. In this case RCR could also be a mandatory USI property.
V=RCR+Count, or
V=RCR+Not Asserted/Count
There is scope for time-based business models for content usage, for example online rental. The CPCM Framework thus includes USI to allow content usage within a specified time window only.
The Time-Based Restriction (TBR) UR is set by applying one or both of the “FROM” and “UNTIL” parameters in the TBR USI.
An alternative time-based UR is based on usage within a relative time after the content is received, by applying the “FOR” parameter.
The TBR UR could be assertive, or alternatively could be mandatory, if the parameter “restriction not asserted” is also defined in the USI.
T=1 or both of {FROM+date/time(absolute); UNTIL+date/time(absolute)} or {FOR+data/time(duration) or Not Asserted}
Some content providers require, as a matter of principle or by regulation, to not protect their content by means of cryptographic tools, i.e. scrambling. The CPCM Framework includes such a USI tool, the “Do Not Scramble” USI (DNSC). This is optional USI. If not set then the content is scrambled by default within the CPCM Framework.
S=DNSC
Some content providers maintain the commercial requirement to restrict the propagation of valuable content to within a certain realm, once the content has been acquired by a consumer.
The CPCM Framework offers a UR to characterize this property in content. The following usage properties are valid for the Propagation Restriction UR/USI:
Restrict to Localized Authorized Domain (RTLAD)—an item of content with this state applied will not be allowed to propagate by electronic transfer beyond the close vicinity of the point at which that content entered the consumer environment, within the respective Authorized Domain (AD). In practical terms this could mean the Local Area Network (LAN) in which the receiving device is connected, for example in the user's main dwelling, i.e. excluding live transfer to the secondary dwelling or to a mobile device.
In the CPCM Framework, the USI Propagation Restriction Property is Assertive USI. If no Propagation Restriction Property is given in a content item's USI, then that content shall be protected by the CPCM system but not restricted with regards to its movement within the CPCM system, subject to the settings of the content management USI for that content.
Alternatively, content within the CPCM framework can carry USI for various propagation restrictions, according to the aforementioned rules, whereby at least one default propagation restriction is given.
R=0 or 1 to n of {RTAD, RTLAD, RTGA, RTLE, CE, EXT, PRNA} according to the aforementioned hierarchy
The prime area for application of the invention is with audio-visual content which is carried or stored in an MPEG-2 Transport Stream [5]. Content disseminated by digital television broadcast is already in this form. Some new forms of content delivery will also use the same format, e.g. video-on-demand over Internet Protocol (IP) services. It can also be applied to MPEG-2 Program Stream format, currently used for example for audio-visual content stored on a Digital Versatile Disk (DVD). The invention thus also allows seamless perpetuation of content URs when content might be converted between these two formats.
Currently digital television services carry MPEG-2 based audio and video content. In the future there will be increasing scope for other content formats, for example MPEG-4 AVC (video) and AAC (audio), but these services also use MPEG-2 Transport Streams as the method of carriage.
According to the present invention, USI is carried in the MPEG-2 Trans-port Stream along with the content whose URs the USI describes. It is however feasible that the same USI coding method be used to carry the USI separately from the content itself, for example within a Content License (CL), a secure set of data associated with the content in a content protection or DRM system.
The following table shows the generic syntax of USI, where the first set of content management usage properties specifies the USI for the content throughout the CPCM system. This need not be present if at least one propagation restriction entry follows, containing the respective content management USI. If the CPCM system-wide content management USI is present, then additional content management USI can be specified after each of the eventual propagation restriction entries. This is how different usage rules can be set for different realms of the CPCM system.
There could be more than one GA realm specified, but there should only ever be one LE and/or one RTAD and/or one RTLAD propagation restriction set of USI specified.
Many combinations of realms and respective content management USI settings will not make sense, but the coding rules described earlier ensure that illogical combinations are avoided.
In general it can be expected, for example, that there should never be more restrictive content management rules specified for the smaller propagation realm, e.g. for the LE versus the GA, or for the RTLAD versus the AD.
Tab. 1 shows the generic preferred coding of the set of usage properties, parameters and arguments. This is applicable to both of the embodiments using MPEG-2 Systems (namely DVB SI, and copyright descriptor). N represents the number of usage state information properties contained in the instance applied to an item of content. Tab. 1 is also a schema for a decoder.
Tab. 2 shows the syntax for each usage state information property, and the respective usage parameters and arguments.
Protection of USI against manipulation: USI table contains a keyed hash of the USI information. In the case of encrypted content, this keyed hash shall preferably be encrypted using the content key.
Thus the usage state information is preferably included in data sections that are required to be repeated regularly in the content stream to which the information is associated.
DVB SI [8] defines a syntax for carrying data related to the audio-visual services carried in the DVB Transport Stream.
In this embodiment a new SI descriptor is defined, preferably called the “usage state information descriptor”, and is assigned a descriptor tag value.
The usage state information descriptor is carried preferably in the Event Information Table (EIT), indicating the usage state information for that event. The usage state information descriptor can be carried in all types of EIT, thus allowing the advanced indication of usage state information for future events using the same method of communication.
The usage state information descriptor is preferably duplicated in the Service Description Table (SDT), and either alternatively or in addition, in the Program Map Table (PMT), indicating the usage state information of the currently running event for that service.
Tab. 3 shows the preferred syntax of the usage state information descriptor in DVB SI. The previously described generic coding syntax is applied to the DVB SI descriptor structure.
The invention can also be applied to ATSC [9] systems. Here, similarly to how the invention is applied to DVB systems, a new descriptor is defined to carry usage state information for the associated content.
MPEG-2 Systems [5] specifies the “copyright descriptor” as a tool for identifying associating a particular registration authority and content identifier to the content.
This preferred embodiment of the invention foresees the establishment of a new registration authority that might also define a corresponding CPCM or DRM system that would apply the copyright descriptor to associate the content with UR and corresponding USI as disclosed by the invention.
The “additional_copyright_info” field in the copyright descriptor is expanded to contain the coding of USI according to the present invention.
Tab. 4 shows the preferred syntax of the usage state information descriptor when applied to the MPEG-2 Systems copyright descriptor. The previously described generic coding syntax is applied to the copyright descriptor structure.
The copyright descriptor with usage state information according to the present invention can be applied to content carried in both streams defined in [5]:
It is feasible to define an XML schema code fur CURML which indeed does have the same scope as the binary method of coding USI. Such a schema may be useful in certain content exchange environments.
The present invention covers the following aspects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04017019.3 | Jul 2004 | EP | regional |
| 05010686.3 | May 2005 | EP | regional |
| 05013393.3 | Jun 2005 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/07801 | 7/18/2005 | WO | 00 | 1/19/2007 |
