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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