CHICAGO As Sprint PCS and other carriers ready wireless video applications for delivery later this year, chip companies are racing to optimize MPEG-4 and other key audio/video decoding software for their silicon platforms. The activity has renewed the debate over the relative merits of DSPs and general-purpose processors as companies seek to combat the obvious drawbacks of running power-hungry and time-intensive streaming applications on cellular handsets.
PacketVideo, a leading wireless video technology company, announced at the PCIA Global-Xchange trade show here this past week that it's optimizing its MPEG-4 decoding software for such digital signal-processing platforms as Texas Instruments Inc.'s new Open Multimedia Application Platform (OMAP) and Lucent Technologies' StarCore SC100.
PacketVideo's streaming media decoder already runs on the ARM and StrongARM RISC cores, tapping the baseband processing power of those microprocessors. But the company sees value in tailoring its decoding software to widely used DSPs, said Edward Suski, director of technical marketing at PacketVideo.
Battery efficiency and real-time performance are the primary reasons some handset vendors prefer running streaming media decoding software on a DSP rather than a microprocessor, said Corbett Kull, manager of the DSP Labs at PacketVideo. "DSP offers a zero-wait-state memory, while the accelerators available on such a DSP enable certain instructions to run much faster," Kull said.
TI and PacketVideo showed off PacketVideo's streaming video applications running on a TI OMAP development board at the show. "As video becomes a prime application for 2.5G and 3G devices, we believe it's very important to open up not just a RISC processor but a DSP to third-party application development," said Randy Ostler, marketing manager for wireless computing at TI.
OMAP is a hybrid architecture comprising an ARM9 processor and the TMS320C55X DSP. The ARM processor is used for such functions as fetch-and-find and random searching; the DSP handles the math-intensive algorithms. In short, the "ARM is responsible for the user interface and the DSP for real-time audio/video," said Ostler. "In our study, we've found that MPEG-4 decoding software run on our C55 DSP consumes half the processing resources and half the power consumed when running on a general processor."
According to TI, in designing a 2.5G or 3G cellular phone, vendors are expected to use yet another OMAP-based ARM/DSP pair in the handset just for handling communication stacks.
PacketVideo's MPEG-4 decoding solution is also being optimized for Intel Corp.'s new XScale "application processor" architecture, which can scale its voltage on the fly from 1.6 volts to 0.75 V to battle the power drain of multimedia apps on cell phones. The scalable voltage feature is particularly important in running MPEG-4, said David Rogers, a product marketing executive at Intel's wireless communications and computing group. The processor can jack up the voltage to speed the decoding of incoming MPEG-4 streams and then quickly kick back to sleep mode.
Intel is also co-developing a DSP architecture with Analog Devices Inc. that will pair with the XScale in wireless handsets, adding "DSP-like, math-intensive performance" in the XScale coprocessor application space, Rogers said.
A few wireless carriers are already committed to delivering wireless video applications, according to PacketVideo, which announced agreements this past week with Sprint PCS and with SK Telecom, South Korea's largest wireless service provider.
Sprint PCS and PacketVideo plan to field commercial vertical-market applications later this year that will feature live-camera, remote-viewing capabilities. According to PacketVideo, participants in the U.S. wireless-video consumer trials held earlier this year with Sprint had embraced PacketVideo's Eye-on-My product, which is being promoted as a tool to monitor activity at preschools or elder-care facilities or to check up on caregivers working in one's home.
SK Telecom, for its part, will conduct a consumer field trial of PacketVideo's wireless media technology in South Korea.