Planning to design a portable streaming-video product? Be prepared, because several design challenges stand in the way. The wide selection of hardware and software that’s available may seem like an advantage, but sorting through those choices can be daunting.
Today, designers have to balance a number of factors— increased memory capacity, greater processing power, wider networking bandwidths, display type, and power-supply architecture— as they tailor their designs for specific applications (Fig. 1). Beyond the balancing act, they must make these components fit together seamlessly, minimize development costs, and expedite time-to-market.
These demands grow more challenging as DVD players, iPods, nanoPods, 3.5G and 4G phones, iPhones, etc., look to add or enhance streaming-video capability. For example, tiny mobile phones with 2-in. screens can now handle streaming video.
Naturally, media-content service providers are anxious to cash in on these opportunities. Several companies offer services that stream video to mobile devices in addition to their IPTV services, which stream video to the home.
Still, designers have to figure out how to manage and display incoming video streams from multiple sources. Moreover, issues like video compression, decompression, coding, decoding, video degradation, jitter, digitization, codecs, streaming methods, and network transports will all affect video quality, user satisfaction, and the product’s ultimate success.
Of all the issues crucial to portable video design, the processor and the software framework reign supreme. On the one hand, the processor must be powerful enough to satisfy performance demands. On the other, it must be able to operate within a software framework that reduces development time as well as reliance on third-party development tools and intellectual property (IP).
Another two-sided situation involves memory: The processor has to support large amounts of memory with minimum impact on the processor’s performance and programming complexity. But it can’t impose a large burden on the power supply, or the user’s viewing time will be short-lived.
Designers of these mobile devices can choose from generalpurpose processors, DSPs, media processors, ASICs with customizable cores, and application-specific standard products (ASSPs). They can even use FPGAs to configure a processor for a portable video product.
“Software compatibility is a big design issue,” says Greg Mar, worldwide technology manager for Texas Instruments’ DaVinci application program interface (API). “You need the latest processors that can enable digital video and have the flexibility to meet different requirements.”
Mar points to the TI DaVinci DM355 processors, which feature lots of processing power for less than $10 each in OEM lots, as an example (Fig. 2). “A design engineer needs software that can work ‘out of the box’ and support an operating system of choice,” he says. “Designers don’t need to relearn what they already know. Working with the right development platform is the key.”
TI’s OMAP3525 and OMAP3530 use DaVinci technology for DSP video-centric portable applications. “The DaVinci and OMAP platforms are flexible enough to allow the user a choice of display, be it internal to the product or external to a TV set,” says Kevin Hawkins, TI’s OMAP marketing manger.
The DaVinci and OMAP platforms are based on the superscalar, 600-MHz, ARM Cortex-A8 core, which has four times the processing power of 300-MHz ARM9 devices. The ARM is a 32-bit RISC core and is the most widely used processor in embedded systems found in portable video products. Marvell’s XScale processor family also uses this core.
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