Interactive video distribution systems – Access control or blocking – With encryption or scrambling of video signal
Reexamination Certificate
1998-10-15
2003-11-18
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Access control or blocking
With encryption or scrambling of video signal
C725S089000, C725S094000, C725S113000, C725S133000, C380S241000
Reexamination Certificate
active
06651250
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a system for receiving a digital broadcast in an information processor such as a computer. More particularly, the invention relates to a method of processing received data.
BACKGROUND OF THE INVENTION
Description of the Related Art
Examples of the prior art are disclosed in the following literature, by way of example: (1) Japanese Patent Kokai Publication JP-A-8-307784, (2) Japanese Patent Kokai Publication JP-A-8-237154 and (3) Japanese Patent Kokai Publication JP-A-5-328320.
JP-A-8-307784 discloses a method of receiving a TV broadcast at a personal computer which involves a method of making a connection when an analog terrestrial TV broadcast is received by the personal computer. Specifically, since a video signal, audio signal, data signal and control signal appear at the output of a broadcast reception card, a personal computer can be converted to an analog terrestrial TV receiving system if c the card is connected to circuitry within the personal computer. However, since a digital broadcast employs a receiving scheme different from that of an analog broadcast, it is not easy to realize the proposed system.
JP-A-8-237154 teaches to connect a tuner card for a digital broadcast to a personal computer, whereby the digital output of the tuner is input to the personal computer so that the personal computer can receive the digital broadcast with ease. With this set-up, however, a subscription broadcast cannot be received.
In order to receive a subscription broadcast, an IC card is necessary when the broadcast is a digital satellite broadcast.
FIG. 11
illustrates the configuration of a typical digital satellite broadcast receiver system according to the prior art. As shown in
FIG. 11
, a digital satellite broadcast receiver
119
, to which a parabolic antenna
101
is connected, includes a digital satellite broadcast tuner
102
, a descrambler
103
, a transport stream decoder
105
, a DRAM
104
, a decoder
106
in compliance with the MPEG2 standard, an SDRAM
107
, a video encoder
108
and an audio D/A converter
109
. The computer side of the receiver has a microcomputer
112
, a ROM
113
, a DRAM
114
, a network control circuit
118
for controlling the connection to a telephone line, a modem
117
, a control unit
111
associated with a remote controller and control panel, and an IC card interface
116
. The microcomputer
112
sends data to and receives data from the transport stream decoder
105
and descrambler
103
via a system bus
110
.
In the conventional system shown in
FIG. 11
, the special-purpose IC card
115
is required in order to view and hear a subscription broadcast. Information such as the channels capable of being received from a subscription broadcast for which the subscriber has given agreement is stored on the IC card and the card is always necessary to acquire the subscription broadcast. The conventional digital satellite broadcast receiver is controlled by the equivalent of a 16-bit microcomputer and performs operations such as the descrambling of a subscription broadcast. In order to decode MPEG2 transport streams, use is made of an LSI chip in special-purpose hardware and section formation of packets is carried out using a memory connected to or incorporated within the LSI chip.
Further, JP-A-5-328320 discloses an arrangement in which, in a manner similar to that of JP-A-8-307784, character information for an analog terrestrial character multiplex TV broadcast is input to a personal computer by an RS-232C interface. However, this arrangement does not support digital broadcast.
SUMMARY OF THE DISCLOSURE
The following problems have been encountered in the course of investigations toward the present invention.
Thus, the conventional systems have the following problems:
One problem is that section formation of packets constituting an MPEG2 transport stream is carried out by a special-purpose MPEG2 transport stream decoder LSI chip and a memory connected to or incorporated within the LSI chip. The reason for this is that the processing capability of the microcomputer that implements overall control is not adequate for carrying out the section formation.
A second problem is that in order to perform descrambling to receive a digital satellite subscription broadcast, a microcomputer executes processing which includes fetching a descrambling code that has been written to an IC card and descrambling scrambled packets contained in an MPEG2 transport stream output by a digital tuner. Since overall management of a digital satellite broadcast receiver is carried out by the microcomputer, cost would be too high if management were performed by a processor other than this microprocessor.
A third problem is that an MPEG2 decoder LSI chip comprising hardware is necessary in order to decode compressed video and audio in the digital satellite broadcast receiver. The reason for this is that the capability of the microcomputer controlling the receiver is not sufficient for executing MPEG2 decoding. Even if a processor having sufficient capability is developed, once the product is shipped the existing processor cannot be easily replaced by the processor of higher capability.
Accordingly, an object of the present invention is to provide a digital broadcast receiving system for use with an information processor, in which use of a special-purpose LSI chip is unnecessary for forming a section of packets of an MPEG2 transport stream, the section formation may be carried out by a computer CPU with the minimum amount of hardware, and it is unnecessary to use a special-purpose microcomputer for the descrambling that is needed to receive a subscription broadcast, with the descrambling being implemented by the minimum amount of hardware by performing control using the computer CPU, thus making it possible to exploit the processing capability of the computer CPU to the maximum extent.
Further objects of the present invention will become apparent in the entire disclosure.
According to one aspect of the present invention, the foregoing object is attained by providing a system for receiving a digital broadcast in an information processing apparatus such as a computer, the system having means for filtering an MPEG2-based transport stream and means for transferring the filtered stream to the system memory of a computer by DMA.
More specifically, the system according to the present invention includes filtering means for filtering packets, by a specified packet ID (termed PID), from a MPEG2-based transport stream output by a descrambler, DMA control means (DMA controller) for transferring the filtered output to a system memory of a computer, and a FIFO (First In First Out) memory, which is provided between the filtering means and the DMA control means, for when the computer bus is congested.
In another aspect of the invention, the system includes means for accessing an IC card from a computer CPU, and means for accessing a descrambler.
More specifically, the system according to the present invention includes an IC card interface for accessing an IC card, an RS-232C controller for performing communication of data, and an input/output (I/O) controller adapted so that access is possible from a computer CPU, the input/output controller providing a signal descrambler access and a signal for controlling a tuner.
Further, since accessing of an IC card involves a data transfer speed that is very low in comparison with the data transfer capability of a computer bus, a FIFO memory is provided between the RS-232C controller and the input/output controller in order to lighten the load on the computer bus when the IC card is accessed.
In operation, a MPEG2 transport stream output by a digital tuner is descrambled by a descrambler if the broadcast is a subscription broadcast that has been scrambled. If the broadcast is not a subscription broadcast, then the transport stream is allowed to pass through and is output as is.
The MPEG2 transport stream output by the descrambler is filtered based upon packet IDs contained in packets, only packets desired
Bui Kieu-Oanh
Dickstein Shapiro Morin & Oshinsky LLP.
Faile Andrew
NEC Corporation
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