Interactive video distribution systems – Access control or blocking
Reexamination Certificate
1999-04-22
2003-07-08
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Access control or blocking
C725S031000, C725S080000, C725S131000, C725S133000, C380S210000, C380S211000
Reexamination Certificate
active
06591419
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital multi-media device such as a digital video device and an arrangement and method which allows the device to communicate with another device on a common bus.
2. Description of the Related Art
In the field of digital video processing, it is known to code digital video signals such that special processing is needed in the receiver to be able to reproduce the video signals. In particular, it has been proposed to provide a Conditional Access Module which can perform all of the descrambling and other conditional access functions of the digital TV receiver. This allows conditional access and signal decoding functions to be separated from a host receiver, such that a generic digital TV receiver can operate with many different conditional access systems in different Conditional Access Modules.
To allow communication between a Conditional Access Module and a digital TV receiver, a Common Interface has been proposed and standardized by CENELEC (EN50221 Common Interface Specification for Conditional Access and other Digital Video Broadcasting Decoder Applications). This standard Common Interface defines a transport stream interface in which various virtual channels are time multiplexed and a Command Interface over which various additional command data are sent. The Common Interface thus allows connection of a Conditional Access Module to a digital TV receiver or indeed any other digital video device.
As a basis for the present invention, it is now recognised that it would be advantageous to provide a Conditional Access Module on a local network of digital multi-media devices including audio and video devices, such that the various functions available in the Conditional Access Module can be provided to all of the devices on the network.
A standard has been proposed for connecting together various digital video devices on a local network. In particular, IEEE 1394 is a 1995 IEEE standard for a high performance serial bus and defines a bus, which will be referred to as an IEEE 1394 Serial Bus, for connecting together various digital consumer audio/visual products.
The IEEE 1394 specification defines a physical connector, electrical signalling and a set of link and transaction protocols allowing the serial bus to self configure and carry audio, video and control information efficiently.
A further set of additional protocols have also been defined to carry MPEG data and provide control mechanisms between different items of equipment on the IEEE 1394 Serial Bus. These protocols are defined in the specification “Digital Interface for Consumer Electronic Audio/Video Equipment” (IEC 1883).
The IEEE 1394 specification defines mechanisms and protocols to carry two types of data, namely asynchronous and isochronous data.
Asynchronous data generally has no requirements on the transport mechanism regarding time, for example the jitter imposed or the delay in transmission. This data can be used for instance for file data or general command and status data.
On the other hand, isochronous data has strong requirements for low jitter and a fixed or bounded delay for transmission and may be used for MPEG coded audio and video data.
OBJECTS AND SUMMARY OF THE INVENTION
In view of the developments with the IEEE 1394 Serial Bus, it is now considered to connect a Conditional Access Module to a number of different digital multi-media devices such as audio and/or video devices using the IEEE 1394 Serial Bus. Unfortunately, however there are significant problems in implementing such a system. IEEE 1394 related protocols have been developed that are intended for use with streams of single channel MPEG data and its own protocols are provided for various command data. In particular, the Conditional Access Common Interface and the IEEE 1394 serial bus have set different standards.
A first aspect of the present invention concerns the problem that, for the Common Interface, the transport stream sent to the Conditional Access Module includes all of the virtual channels and hence takes up a significant amount of the bandwidth available over the IEEE 1394 Serial Bus.
The first aspect of the present invention also deals with the problem that it is often not sufficient to send to a Conditional Access Module merely the virtual channel which it requires for descrambling, since other data in the transport stream may be required by the Conditional Access Module.
A second aspect of the present invention concerns implementing the Transport Stream Interface of the Common Interface over an IEEE 1394 Serial Bus so that the transport stream data of the interface may be communicated over the IEEE 1394 Serial Bus.
A third aspect of the present invention concerns implementing the Command Interface over the IEEE 1394 Serial Bus.
The fourth aspect of the present invention concerns implementing the Command Interface over the IEEE 1394 Serial Bus.
According to the first aspect of the present invention, there is provided a digital multi-media receiver comprising:
an output for an IEEE 1394 Serial Bus for transmitting a transport stream to a Conditional Access Module on the bus;
a reader for reading the contents of a transport stream and identifying data which is not required for processing by a Conditional Access Module;
a stripper for stripping out at least some of the identified unrequired data from the transport stream; and
a transmitter for transmitting through the output all of the remaining data of the transport stream which has not been stripped.
According to the first aspect of the present invention, there is also provided a network of digital multi-media devices connected by means of an IEEE 1394 Serial Bus, the network comprising:
a device for transmitting a transport stream over the IEEE 1394 Serial Bus; and
a second device for receiving a transport stream over the IEEE 1394 Serial Bus; wherein
the first device includes a reader for reading the contents of a transport stream and identifying data which is not required for processing by the second device;
a stripper for stripping out at least some of the identified unrequired data from the transport stream; and
a transmitter for transmitting to the second device over the IEEE 1394 Serial Bus all of the remaining data of the transport stream which has not been stripped.
According to the first aspect of the present invention, there is also provided a method of transmitting a transport stream over an IEEE 1394 Serial Bus, comprising:
stripping out of the transport stream identifiable unrequired data so as to reduce the bandwidth of the transport stream.
Thus, since the only data to be stripped from the transport stream is that data which is positively identified as not being required by the Conditional Access Module, the stripped transport stream contains all of the data required by the Conditional Access Module. Furthermore, in practice, the stripper will be stripping out virtual channels containing broadcast program content data. The broadcast program content data takes up the most significant proportion of the bandwidth of the transport stream and, therefore, stripping out this data will have a very significant effect on reducing the overall bandwidth of the transport stream.
The present invention is applicable to any type of digital multi-media device, including devices handling audio data, video data, other multi-media data or a mixture thereof. It is particularly advantageous for digital video devices handling at least video data.
Preferably, the transport stream is an MPEG-2 transport stream and is transmitted in isochronous channels under the IEC1883 format.
A table of program specific information (PSI) is provided in the MPEG transport stream, such that unrequired parts of the transport stream can be identified for stripping.
The receiver is able to determine which streams to strip out not only from the PSI but also the user state, i.e. which program the user wishes to watch or record, etc. As receivers in general can only display one picture at a time then that is the one to be descr
Barry Richard John
Paskins Adrian Charles
Webster Michael Alexander
Faile Andrew
Frommer William S.
Frommer & Lawrence & Haug LLP
Huynh Son P.
Simon Darren M.
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