The debate between flexibility and cost is always a changing one, and broadcast equipment makers are facing a change in the way they put systems together as system on chip solutions are starting to displace the FPGA makers.
The traditional approach for broadcast encoders sees designs being implemented in large, expensive FPGAs as a way of encapsulating all the knowledge and expertise in image quality and system management.
Now that the latest video encoding standard, MPEG4part10 (also called H.264 and the Advanced Video Codec – AVC) has settled down and is now being implemented in encoders for high definition satellite TV and IPTV over the phone lines, SoC providers are now looking to provide this key technology almost as a commodity item for Tier One encoder makers such as Harmonic.
“There is a shift in technology and the way Harmonic designs encoders and that depends at the end of last year,” said Arnaud Perrier, senior product marketing manager for Advanced and HD Encoding. “We realised that the technology hadn’t been ideal and we were getting feedback from customers on the first MPEG4 deployments.
“We took reference models from codec vendors and we used those internally in a ‘shoot out’. Some were ASICs, some were FPGA, some DSP, and we spent a lot of time doing that. One technology in particular, which was ASIC-based, blew the others out of the water. We were really surprised. It gave us better density, with 4HD channels in 1RU rack unit.”
US chip startup Telairity identified the same trend and has developed a single chip which combines five independent very long instruction word (VLIW) processing cores, a video controller, and a DRAM controller supporting an I/O bandwidth up to 5.3Gbit/s in the SoC. However, equipment makers weren’t interested in just a chip.
The company launched an encoder reference platform that uses eight of these chips with Telairity’s own software to encode one channel of AVC in real time, including key tools to improve the quality of the image, such as CABAC, replacing up to 24FPGAs and DSPs.
Similarly Thomson has developed an SoC for encoding that samples this month. The 90nm Mustang chip has two ARM processor with six programmable DSPs and dedicated hardware for video-specific tasks like motion estimation and entropy encoding, as well as a 10Gbit/s PCI Express bus. It will be used in the ViBE encoders shipping at the start of next year from Thomson subsidiary Grass Valley.
“Grass Valley is in a unique position to develop this extremely complex single-chip solution,” said Marc Valentin, president of Grass Valley. “The result is that the ViBE encoder based on the new chip will offer incredible performance and flexibility and we will be able to build the chip into other products across the range from format converters to servers and production switchers.”
However, this commodity view has been dismissed by other encoder makers, as the implementation of the algorithm is still key to quality of the video encoding.
FPGA fights back
But the FPGA makers are not too worried. Altera has been focussing on the broadcast market for several years, and points to PC-based encoder maker Ateme. “Three years ago their solution was DSP based and now it is on a single FPGA for an encoder with broadcast quality,” said Herve Mer, Market Development Manager for Broadcast and Consumer at Altera Europe.
Similarly, Xilinx sees its role as providing more of the system hardware and interfaces, with the move to 65nm driving up performance and driving down the cost per function. Xilinx is shipping samples of its Virtex-5 LXT FPGAs, which are the first FPGA with a hard-coded PCI Express Endpoint and Tri-mode Ethernet Media Access Controller (MAC) blocks for broadcast systems.It been working with several customers, such as Agilent, in its early access program since June 2006, and while the parts are sampling now they will not going into production until 2008.
And the FPGAs are widely used across broadcast. For example, Canadian equipment maker Miranda is using the latest Xilinx FPGAs for its multi-room, multi-image display plus HD/SD routing in a single, expandable chassis that can display up to 96 separate streams of video on eight different screens.
Similarly, designers of video compression equipment have used banks of FPGAs and DSPs to implement the latest standards.
The latest process technology opens up new opportunities for SoC devices in high quality broadcast applications systems, and the systems will be more of a combination of different devices and technologies. This gives designers even more opportunity to get the best performance out of innovative system design.