[Technology Report]
Lights, Camera, Process!
With an ever-expanding application base, digital video processors target performance needs through specialization and innovation.
“We need programmability to support codecs not available today in highly changeable environments like video communications,” says Andrews. “At the other end, where standards are well known, we use fixed functions to lower cost.”
Products such as TI’s OMAP35x family simply augment ARM processors with camera and image signal-processing hardware, while devices like the DM6467 DaVinci processor combine an ARM, a DSP, and dedicated hardware for real-time transcoding of video from one format to another. Such a range delivers an almost bewildering diversity. “If we had to characterize our products right now it would be all over the map,” says Andrews.
Yet companies are trying to keep things simple for developers. Texas Instruments, for instance, created a unified software infrastructure for its digital video processor platforms that allows developers to begin creating applications before finalizing platform selecting, according to Andrews.
HIGH DEFINITION DRIVES PERFORMANCE DEMAND The move to high-definition (HD) television may be tipping the scales in favor of targeted devices. The pressure is on television device vendors to also boost performance in many areas. According to Ken Lowe, vice president of strategic marketing at Sigma Designs, television video processing has a four-stage pipeline: receiving and demodulating the signal, decryption for digital rights management, decoding of the compressed video, and backend processing such as noise reduction and edge enhancement.
“As we move forward, we have to make each stage better and integrate more of the pipeline on chip,” says Lowe. Vendors also have to provide extra performance to handle applications software. “Three years ago it was ‘who is supporting H.264?’” says Lowe. “Now, it’s ‘who has enough CPU capacity to power the user interface?’”
There’s also a need for more video processing power. Digital broadcast television is rapidly moving through 780-line resolution to 1080-line interlaced (1080i) and on to 1080-line progressive (1080p) formats. IP-based video is having to follow suit. Lowe notes that this will jump data rates by a factor of four as standard-definition MPEG-2 gives way to HD H.264.
“Even with more efficient compression, we need more horsepower,” says Lowe. Sigma Designs responded to this need with its 8654 IPTV media processor, targeting STBs and Blu-ray players, which stepped up performance by 50% each in the CPU and memory interfaces, according to Lowe.
In addition to increasing demand for processing power is the ever-present need for higher integration. “The next stage will be integrating the front-end servo control for Blu-ray and who can enhance the television image at the back end,” says Lowe.
The complex dance of conflicting demands for performance, low cost, high integration, and programmability that has spun out so many variations in the broadcast and IP television portions of the digital video market isn’t quite as intense in other segments. For them, requirements are a little more clear-cut and the products targeting them more are consistent in their approach. Video processing for studio and content provider equipment is an example.
Studio and provider equipment must handle many different digital video formats and be able to freely convert among them—the faster, the better. Many of these formats are standards-based, so dedicated hardware is useful. But the long service life of such equipment also calls for programmability as a hedge against technology evolution.
Similarly, some aspects of the video telephony market have a strong need for programmability. “A consumer video phone may be satisfied with H.264,” says TI’s Andrews. “But an enterprise product will need more flexibility because of its long installed lifetime. Also, enterprise customers can afford the expense.”
Digital video processors for these markets, then, tend to follow the coprocessorenhanced DSP model for performance rather than focusing on high integration and low cost. The TI DM6467 is one such example.
SURVEILLANCE SEES DIFFERENT REQUIREMENTS Surveillance applications, on the other hand, predominantly require programmability to handle image-processing tasks. Codec formats aren’t an issue. As long as the video processor can get data from the camera, format is of little concern. It’s the image processing that counts.
“In the highly competitive surveillance camera market, companies seek to differentiate their products,” says Mike Yu, vice president of Vimicro. “Digital video processing capabilities can provide companies in this market with an edge.”
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