[Product Innovation]
Controller IC Is Gateway To Multiple, Secure A/V Sources
Multiple transport ports, plus a variety of demultiplexing and descrambling algorithms in a single IC, fulfill the requirements of personal video recorders and set-top boxes.
Following descrambling and demuxing, the output port (T/S out) feeds any one of the three arriving input streams to a source decoder IC, like the TeraLogic TL850 decoder. Any of the arriving transport streams coming in can be routed through the chip through any of the different blocks. Or, an arriving transport stream can skirt around all the processing blocks and go directly to a DTV decoder via transport out.
The other I/O port is included for I2C, SmartCards, IR, GPIO, and UART. I2C is normally used for controlling slower peripherals (400 kbits/s) like the tuner ICs and SmartCards for providing keys to the descramblers, IR for I/O to/from an infrared remote control or keyboards, and UARTs and GPIO for miscellaneous I/O.
The on-chip descramblers are an essential feature. They decode the encrypted data stream arriving with content copy protection, which is often the case in a set-top box or a TV—pay-per-view movies or personally addressed data, for instance.
To decode a stream into the clear, both the correct descrambling algorithm and the correct key are required. The combination of the key and the descrambling algorithm enable the STB/PVR controller IC to decrypt the transport stream so that it can then be fed to the demultiplexer and sent on to the decoder. TeraLogic believes that the STB/PVR controller IC has more on-chip algorithms than any other on the market.
There are two descramblers. Each can decrypt an arriving transport stream and deliver video, audio, and data content in the clear—regardless of whether the stream is arriving through cable, terrestrially via a network interface module, or through an external set-top box. In the case of terrestrial signals, many arriving programs are "free to air," so they aren't encrypted. But this role is changing, as broadcasters seek further revenue-generating services. The descramblers support a variety of worldwide descrambling algorithms, including DVB, DirecTV, DES-ECB, MPEG DES, Triple DES-CBC, and Multi-2.
As time goes on, there will likely be more protected content. A common example today is pay-per-view movies, where streams arrive encrypted and once payment has been confirmed, the set-top box or TV is empowered to decrypt the protected stream.
A descrambling key can be supplied by a SmartCard. Alternatively, in the case of open cable systems, the whole stream is passed through a PCMCIA-form-factor card that's installed in a point of deployment (POD) module.
There are either one or two demultiplexers. Each one receives an encrypted or else a decrypted stream of audio, video, and data, separates out the information by type, and feeds each to a buffer. The demultiplexers are microprogrammable engines, so their algorithms can be changed whenever new standards come out or if there arises a need to change the behavior of the demultiplexing unit. Thus, the STB/PVR controller IC isn't rendered obsolete due to changing transmission standards. Additionally, it can be enhanced even further for proprietary PVR systems.
A Plethora Of Buses The STB/PVR controller IC has been configured with a unified memory architecture (UMA). This enables both the external CPU and the STB/PVR controller IC to share identical memory via the 32-bit SDRAM interface. The memory controller, which is effectively shared by the CPU and the STB/PVR controller IC, unifies the memory for the STB/PVR controller chip and anything else connected to it that needs memory. The benefit is that it prevents memory chunks from being scattered around the system by concentrating all memory into one place. Therefore, the UMA aids in holding down the cost of the overall system.
Consequently, to access its memory, the CPU actually goes through the STB/PVR controller IC with the latter acting as memory controller. A 16-bit local bus connects to Flash and EPROM and controls fast peripherals like IEEE-1394 devices and open cable POD modules. In addition, the IC acts as a bridge between the CPU and PCI bus, enabling access to a wide variety of inexpensive PCI peripherals.
A dual-channel IDE interface provides for the connection of up to two disk drives to the IDE bus. Both drives can then be used for storing incoming (or outgoing) transport streams in PVR appliances.
There are two SmartCard interfaces. They are used for CA applications to handle encrypted data arriving on one or more of the transport streams or from the disk drive. Each SmartCard interface functions in conjunction with the on-chip descramblers and perhaps a POD module. The key contained in the SmartCard authorizes a descrambler to decipher the arriving encrypted transport stream producing clear video, audio, and data.
The PVR I/O port is the key feature of the STB/PVR controller IC because it allows transport streams or elementary streams to be captured for viewing later, or for a pause-and-play capability. Elementary streams are the streams delivered by a demux.
The PCI Bus is a general-purpose bus for interfacing with other components in the system. For a long time, the PCI Bus has been perceived as solely PC-oriented. But over the past several years, it has become well accepted in the consumer electronics industry. Plus, now that such a large number of PCI-style components are in the marketplace, it has become quite convenient. Furthermore, PCI is an easy way to download software supplied by TeraLogic or written by the product designer, or to debug a DTV system.
The CPU Interface (SysAD Bus) is a standard 32-bit bus for connecting a MIPS-style microprocessor. The STB/PVR controller IC is compatible with MIPS microprocessors from a variety of manufacturers.
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