Fixed-point DSP pursues midrange receivers
By Stephan Ohr, EE Times
Jun 20, 2002
URL: eetimes.com
SAN FRANCISCO After using a floating-point DSP to sew up the market for audio decoders in high-end audio-video
receivers (AVR) for home theater sound systems, .Analog Devices Inc. is now going after the midrange portion of
the AVR market with a fixed-point version of the same 32-bit processor.
Called the Melody 32, the chip provides eight-channel surround sound as well as an SRS Circle Surround II. It
decodes Dolby Digital-encoded bit streams, Dolby Digital EX, Dolby Pro Logic II, DTS-ES Extended Surround,
DTS Neo:6, THX Surround EX, THX, AAC, MP3 and PCM. "We've chosen the software route," said Ashok Kamath, who
manages ADI's audio product line from India. "When a DVD is inserted, the DSP automatically detects the kind
of bit stream represented and kicks in the appropriate decoder [stored in flash memory]," he said.
ADI's Sharc DSP has been the darling of high-end AVR makers in Japan , including Sony, Denon, Pioneer and
Kenwood, said Mike Haidar, product line director for software and systems technology at the DSP division of
ADI (Norwood, Mass.). Brochures for products like the Sony 9000ES DVD player (a $1,000 receiver and MPEG image
decoder) use the Sharc name as part of their promotions. The 32-bit floating-point processor provides a higher
dynamic range and lower noise floor than the 24-bit processors promoted by Zoran, Motorola and Cirrus Logic,
according to ADI.
The fixed-point unit introduced this week provides many of the same advantages as the floating-point unit,
though it is aimed at $200 to $500 AV receivers, said Haidar. In an announcement that coincided with ADI's,
Kenwood Corp. announced three AV receivers, priced from $200, which use the Melody 32.
Subtle differences
But apart from price, the differences between a 32-bit floating-point audio decoder and a fixed-point unit are
subtle, Haidar said. The fixed-point unit has a more difficult time processing computational overflows, he said.
This will show up on the soundtrack of a movie like "U-571," a submarine battle movie in which the frighteningly
loud depth charge explosions will seem slightly distorted to a trained ear while remaining thrilling and
unnoticeable to practically everyone else. The difference is maybe three or four bits, he said.
"People love 32 bits for multiply-accumulate operations," said DSP industry analyst Will Strauss, president of
Forward Concepts Inc. (Tempe, Ariz.) "The floating-point unit provides some 1300 dB of dynamic range. Who needs
that?" he said. "But the 32-bit fixed-point unit is just as cheap, maybe even cheaper, than a 24-bit processor."
But though it is now No. 1 in the PC audio business, ADI will have to work hard to displace Cirrus Logic Inc.
(Austin, Texas) in the midrange AVR market. Cirrus had approximately 51 percent of the 8.5-million unit AVR
market in 2001, according to Forward Concepts. Yamaha Semiconductor had about 33 percent and Motorola's
Semiconductor Products Sector's 56300 series DSP had about 13 percent. Entrenched as it claims to be in the
high end of the AV receiver market, ADI's share of the total AVR market was only about 3 percent, Strauss said.
Unlike the telecommunications market, consumer electronics has been doing rather well, Strauss said. The 2002
market for AVR receivers is expected to grow to about 10 million units, reaching 12 million to 15 million units
in 2005 if current trends continue.
The Melody 32 platform will decode practically all new digital audio formats and provide bass and delay
management, said ADI's Kamath. The accuracy of the decoders is certified by the format providers Dolby, DTS,
SRS Labs and Lucasfilm THX.
An evaluation board with a copy of the software and schematics is available for $1,250.
+++++++++++++++++++++++++++++++++++++++++++++++++
DSP is dead; long live DSP
By Will Strauss, EE Times
Jun 24, 2002
URL: eetimes.com
For several years, I've heard the cry "DSP is dead." It's ironic, but 100 percent of the people saying that are
peddling a DSP implementation. Mostly, they're trying to point out that their company has a tailored DSP solution
that doesn't require an off-the-shelf programmable DSP chip. Or, they're trying to make the point that for a
specific application, their custom or ASIC implementation of DSP is faster, cheaper, cooler and perhaps prettier
than a programmable DSP from the usual suspects: TI, Agere Systems, Motorola and ADI.
But those companies aren't sitting on their laurels. They have application-specific DSP products based on their
own technology. TI has digital camera, Bluetooth, Wi-Fi, cable modem, digital subscriber line and ASIC chips for
the cellular crowd. Most of Agere's DSP sales are really ASICs for cell and other high-volume sockets, while
Motorola discovered the merchant DSP market in addition to its own cell phone sockets. ADI is a force in ADSL
chips and ASIC modem chips besides its programmable DSP chip line.
With that as a preamble, let it be known that DSP is not just a chip; it's a technology. And it's so pervasive
that almost every MPU and MCU on the planet has added at least a multiplier-accumulator circuit so they can say
that "we also do DSP."
Then there are the finite-state-machine hardware implementations of the DSP algorithms, like in Broadcom's cable modem chips or as part of Nvidia's GeForce graphics chips. "Embedded" DSP implementations like those are never
sold with the DSP nomenclature; rather they are labeled by the end application. So, when you notice an MP3 decoder
or MPEG-4 codec, know that it is based on DSP technology.
Besides the four well-known DSP chip vendors, DSP technology is peddled through another 100 or so, mostly fabless, chip companies . . . many of whom are saying "DSP is dead," albeit their vaunted chips are based on the technology.
Don't be misled. DSP continues to be the technology driver for the semiconductor industry, since only through DSP
can you access the Internet, enjoy multimedia and have digital wireless. So wake up and notice that DSP is the
heart of Bluetooth, Wi-Fi, 3G cellular, graphics, DVDs, digital cameras, digital hearing aids, set-top boxes,
streaming video, voice-over-Internet Protocol, videoconferencing, digital audio broadcast and-if it ever
happens-even HDTV. Long live DSP.
Will Strauss is President of Forward Concepts (Tempe, Ariz.) and is considered an authority on markets driven by
DSP technology (wis@fwdconcepts.com). |
