makers of equipment for the broadcast market are at a cusp in the technology curve, with system-on-chip (SoC) designers looking to displace the FPGA makers in one of their strongest markets.
The traditional curve of technology development sees designs being implemented in large, expensive FPGAs and then migrating to SoC implementations as standards and product requirements solidify. Cost reductions on the SoC then drive down the cost of the equipment and potentially drive the technology into high volume markets.
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. But the latest video encoding standard, MPEG4 part 10 has settled down and is now being implemented in encoders for high definition satellite TV and IPTV over the phone lines.
The technology has matured and SoC providers are now looking to provide this key technology almost as a commodity item for encoder makers.
US chip start-up Telairity 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 were not interested in just a chip.
“We went to all the customers and they said they needed a complete solution”, said Shubha Tuljapurkar, vice-president of marketing at Telairity.
So 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 24 FPGAs and DSPs.
Similarly Thomson has developed the 90nm Mustang SoC with two ARM processors, 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.
“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”, said Marc Valentin, president of Grass Valley.
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.
“With any encoder design it’s about the encoding algorithm, not about the implementation”, said Simon Bigg, senior vice-president of engineering for compression systems at Tandberg Television.
“Although we are here to make the best encoders on the planet we have to provide what the market needs, so we are very, very agnostic about what technology we use. If someone came out with a DCT chip and it was cheaper for us to use rather than implement it in a Xilinx FPGA then we would, but the thing we will never give way in is the flexibility and the ability to put all the blocks together”, he explained.
“Even if it looks like encoding is becoming a commodity, I don’t agree”, said Ovadia Cohen, vice president of marketing at Israeli equipment maker Scopus. “You can find encoding engines coming from companies like LSI Logic or IBM or even from Japanese manufacturers and I do believe that a lot of effort has been invested in that silicon, but it is not enough. There are huge amounts of work that you have to do even if you are using ready-designed silicon or your own design.”
“I think the high end encoders from the top five companies are definitely differentiated from others using the low cost chips. The quality of the video is the number one factor”, Cohen added. He believes the differentiation will be in the system software.
“Now you will find the silicon vendors are developing encoding engines and companies will use those engines. The question is how they will use it. It’s like buying a CPU from Intel – does that mean you have a PC or a laptop? No. The more you invest in pre-processing, statistical multiplexing and many other issues like that, the more you get”, said Cohen.
However, high end encoder maker Harmonic is moving to SoC devices. “There is a shift in technology and the way Harmonic designs encoders”, said Arnaud Perrier, Harmonic’s 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 FPGA, some DSP, and we spent a lot of time doing that. One technology in particular, which was Asic-based, blew the other out of the water. We were really surprised. It gave us better density, with four HD channels in 1RU rack unit.”
Perrier believes this is a different approach. “We have some functions that are hardwired and that frees up a lot of cycles for the other tools that do matter, such as motion estimation and search frames. We have an innovative adaptive and hierarchical search algorithm that means we can process a whole frame at once. We still have DSP and FPGA for certain processes, and there is no one technology that can address everything, but we are taking a really holistic approach.”
But the FPGA makers are not too worried. Altera has been focusing 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.
“Today there’s several ASSP vendors with chips for the consumer market and they design it first to make some money in the broadcast market”, he said. “That’s a dead end solution because you fix it in hardware and it doesn’t develop.”
Similarly Xilinx sees its role as providing more of the system hardware and interfaces. “I think the wide word, multiple processor technologies are valuable but there’s always the issue of connecting to memory or to the SDI data ports”, said Gregg Hawkes, principal engineer for video applications in the advanced products division at Xilinx. “One view is with the geometries being driven down we can throw software at this problem but we always tend to end up with a DSP and FPGA. H.264 isn’t the last compression technology we will have to deal with.”
He also sees the FPGAs as able to mop up other functions such as SDI interfaces and the audio compression. “For example, we can integrate the audio through a reference design for the FPGA, for as many channels as you need, rather than having to add an extra board with perhaps eight extra chips”, he said. “Before it was video, now it’s audio, what will be it be in 2007?”
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.
13-Nov-2006
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