Memory database creation system for encrypted programme material

The invention which is the subject of this application relates to the ability to compile a database of information such as, but not exclusively, broadcast programme material, in a memory and to the generation and provision of identification means to allow the retrieval of the material and to the ability to include a means for processing the material as it is received to allow the generation of the identification means prior to storage.

It is known in the transmission of broadcast material, which can be any or any combination of video and/or audio data and/or auxiliary data that the dame is received at a premises by a broadcast data receiver and that the received data can be decoded and stored in a hard disk drive or other form of random access memory for subsequent selective retrieval which may be provided integral with the receiver or connected thereto. However with the ability to store the material in memory there is the accompanying demand to be able to identify and retrieve the data readily and review the material to allow a selection to be made of a portion of the stored material or the required part of the material to be identified. In order to allow the efficient retrieval of material it is necessary to be able to accurately identify segments of the material at the time of storage so that for example, for video material, the frames of video can be identified and the particular form of frame and coding method used can be identified with respect to each frame for subsequent retrieval and generation of a video display.

The use of the memory is at present complicated by the reception of broadcast programme material which is transmitted in a scrambled or encrypted format to prevent unauthorised viewing of the same. The material can be descrambled by, for example, the payment of an appropriate sum to authorise the descrambling however it is desired that encrypted material should also be able to be stored in a memory and an identification database created. A known solution is to record the broadcast encrypted material, read it from the memory and then parse it to obtain the appropriate start identifier for the material. This solution has the benefit of not requiring the construction of a database of location identifiers but does have the disadvantage of requiring for retrieval, that all of the material data has to be read from the memory at a high rate until the start identifier is located as this is the only reference identification.

The aim of the present invention is to provide apparatus and a method whereby the material stored in the memory is identified with respect to location identifiers held in a database to allow the retrieval of the material and in particular to allow material which may be in an encrypted form when received to be identified and stored while at the same time ensuring the security of the same in storage.

In a first aspect of the invention there is provided a system including a receiver for broadcast data said receiver including a means for identifying and storing broadcast programme material in a memory means and allowing subsequent selected retrieval of material from the memory, characterised in that said system includes the steps of receiving the broadcast programme material and, if the material is in an encrypted format, processing the material using some or all of the steps of data de-scrambling and/or data decrypting and/or data stream parsing to generate a number of location identifiers for respective portions of the material, which identifiers are held in a database for reference and upon selection of an identifier or identifiers, retrieval of a respective portion or portions of material from the memory means.

Thus the system allows for the identification and storage of encrypted broadcast programme material in a memory means and subsequent selected retrieval of the material from the memory, with the system typically including the steps of receiving the broadcast programme material and, if the material is an encrypted format, processing the same, typically using the steps of descrambling or decrypting and stream parsing to be able to generate a number of location identifiers for the material which are held in a database for reference in the retrieval of the memory from the memory means. Typically the material which is referred to in this specification is digital data which can be any of video, audio and or auxiliary data and which , after reception at the broadcast data receiver can be decoded, and if necessary reordered and combined to generate for viewing or listening identifiable programmes, teletext, Electronic Programme Guides or the like.

In a preferred embodiment the encrypted material undergoes a further processing step of copy protection so that when the material is stored in the memory it is protected against unauthorised copying which is of course one of the reasons for the initial encrypting of the data and so the material is held in a secure state in the memory but can be identified and retrieved.

Preferably the processing steps for the encrypted material should be performed as one process so as to prevent unauthorised access to the material when in a descrambled form.

If the broadcast programme material is not encrypted the same is received and identified for storage in the memory but need not pass through at least the processing steps of descrambling and copy protection.

In one embodiment the database of location identifiers which is generated in relation to the encrypted material may also be encrypted to ensure security of the material.

In a further aspect of the invention there is provided a method of generating a database index of the location of specified features of video and/or audio data material relating to a broadcast programme held in a memory device, said material received by a broadcast data receiver from a remote location in an encrypted form and wherein the method comprises the steps of decrypting the data, parsing the data to generate a plurality of location identifiers for respective portions of the material, and storing the said location identifiers in a database, and locally encrypting the material prior to storage in the memory device.

In one feature of the invention the memory device, and processor means for performing the method described above are located in a data receiver which receives the broadcast programme material from a remote source. Typically the programme material received is transmitted in an encoded digital format and the receiver includes means for decoding the received data and generating video and/or audio displays via a television set or monitor and speakers in connection with the data receiver.

In a yet further aspect of the invention there is provided a broadcast data receiver provided for the reception of broadcast digital data from a remote location, the decoding of the data and generation of video, audio and/or auxiliary data for viewing and/or listening via a display screen and/or speakers to which the receiver is connected, said broadcast data receiver provided with or connected to a memory means for the storage of video, audio and/or auxiliary material generated from the received data for selective access at a subsequent time and wherein if said data is received in an unencrypted form, the data is decoded and stored in the memory means in conjunction with a record of the location identifier for said material to allow subsequent retrieval and if the data is received in an encrypted form the data is decrypted, parsed to generate a plurality of location identifiers for respective portions of the data material, and stored, with the said location identifiers held in a database, and the material is locally encrypted to storage in the memory device.

By allowing for the local encryption of the material so the material can be stored securely at the broadcast data receiver or in associated apparatus and still retrieved at a later time for viewing if the viewer is authorised for the decryption of the material.

A specific embodiment of the invention is now described with reference to the accompanying drawing which illustrates a schematic illustration of the system in one embodiment.

In the example it is desired to store received data material arriving in an encrypted stream 2 relating to a broadcast programme, in a memory 4in the form of a hard disk drive for subsequent retrieval and the said retrieval may be for all of the material, portions or excerpts of the same and/or it may be required to fast forward or rewind, pause or perform other search functions on the material in storage.

In one embodiment the memory is provided as part of a broadcast data receiver which includes components to allow the reception of digital data broadcast from a remote location via, satellite, cable or terrestrial systems, the decoding of the data and the generation of a video, audio or auxiliary data for display via, for example a television set. The broadcast data receiver can be provided connected to the television set or as an integral part thereof and equally the memory can be provided as an integral part of the broadcast data receiver, the television set, or can be connected to one or the other.

At certain or all instances the received data can be received in an encrypted form and a database 6 is provided for the memory which allows the storage of location identifiers for the material which are generated before the material is input or recorded onto memory 4.

Thus in accordance with the invention, the received encrypted material 2 is first descrambled or decrypted 8 and then parsed 10 to allow the decision and generation of location identifiers sent to the database 6, which may be in absolute terms or relative to other identifiers, for features in the material data. Some examples of useful features can be, for video material, the start of I,B or P frames, Group Of Picture (GOP) sequences, time codes and/or pictorial temporal references.

Once the location identifiers are generated and stored in the database the material can then be re-encrypted for copy protection 12 prior to the storage of the same in the memory and a memory or disk controller 14 is utilised to generate indexing information for the memory which is stored in the database and allocated against the location identifier for the respective portions of material so that the same can subsequently be found in the memory 4.

Subsequently, when the instant arrives at which some or all of the encrypted material is to be retrieved from the memory, reference to the database 6 can be made to accurately identify and start the supply of the material from the memory from the most relevant or convenient location identifier for the material in response to the retrieval demand. For example if a particular excerpt or portion of the material is to be retrieved, the supply of material could start from the "I frame with a time code nearest a particular time". The material supply is commenced by parsing the database to find the best matched location identifier in the form of a time code and then reference is made to the database index for that material to identify and access the sector of the disk drive memory where the material is held.

As suggested previously it is of advantage for security reasons to have the decryption, parsing and copy protection integrated as one process to form a material processor and the accompanying Figure illustrates in the shaded area 16 how this can be achieved and thereby prevent unauthorised access to the material when in the decrypted form. A further stage can be the integration of the memory controller 14 into the same unit as the material processor 16 and it allows simplified tracking of the storage sector used for the key features which are extracted and used to form the database.

In one further feature the database 6 information may be locally encrypted to provide another level of security.

The invention therefore provides a relatively fast, efficient access to stored material which can be stored in an encrypted, copy protection form and yet allows the location of the material to be identified with reference to a database index.

With the ability to store programme material (video/audio etc) on hard-disk drives (and similar) it becomes desirable to have truly random access, fast-forward, rewind capabilities. To efficiently random access the stream, it is necessary to be able to physically locate say I,P,B or temporal tagged pictures. This invention relates to the construction of a database mapping particular picture properties to physically addressable units, on the storage device. However, in a broadcast environment, where the programme material is encrypted, this invention describes an architecture that integrates broadcast descrambling, followed by stream parsing to form the database, followed by local content protection (rescrambling for subsequent storage). The described architecture specifically the order of processing, offers significant efficiency benefits.