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January
18, 2001, Thursday
Copyright
2001 Cahners Publishing Company
EDN
LENGTH:
460 words
HEADLINE:
Video encoder slims down for spring
DATELINE:Jan.
18, 2001
BODY:WITH
THE NEW YEAR, many of you may have resolved to "lose a few pounds."
Vweb has similar ambitions but with slender silicon rather than
slender bodies in mind. Even though digital-video-recorder pioneer
ReplayTV might be now undergoing financial struggles, industrywide
trends suggest there's a healthy market for various digital-video-capture,
distribution, and time-shifting applications. Vweb hopes to be at
the heart of systems targeting those applications.
The
company's $30 (10,000) VW2000, now in production, encodes to D1
resolutions at a 2- to 15-Mbps constant bit rate, 500 kbps for SIF
(source-input format) resolutions, and as low as 128 kbps for QSIF
(quarter-source input format). High-resolution encoding targets
closed-box archiving--that is, digital VCR--and high-speed intranet-distribution
applications, whereas lower resolution bit rates are more appropriate
for Internet delivery. Vweb touts its part's 500,000-gate logic,
which the company claims is one-half to one-fourth the size of competitive
offerings. Key to the low gate count is Vweb's proprietary motion-estimation
algorithm, whose hierarchical search techniques also promise better
matches at a faster search. The product's firmware needs less than
15 kbytes of memory, which the company asserts is 10% the size that
other vendors' products need. The VW2000 also requires only 4 Mbytes
of external buffer memory, for which it embeds a 32-bit, 166-MHz
SDRAM controller.
The
VW2000's rate-control algorithm tracks 60 parameters, resulting
in a more consistent group-of-pictures size and fewer disruptive
I-pictures. For those who prefer to let Vweb do some of the system
work for you, two production-ready board designs are available.
The PCI-based, $800 (1000) VW2KWIN1 includes a separate MPEG audio
encoder and relies on a PC-host CPU running Windows 98 or 2000 for
control, whereas the stand-alone $1000 (1000) VW2KEMB1 includes
a MIPS control CPU and serializer. Both boards accept composite
or S-Video and dual-channel analog audio. Both cards output MPEG-2
elementary and packetized elementary streams; the VW2KEMB1 adds
support for MPEG-2 transport streams.
Vweb's
chip is low-cost, particularly when you consider the low-density
and low-cost external-DRAM requirements, at least until 16-Mbit
DRAMs become rare chips. However, it is a video-only, encode-only
architecture. Other companies targeting MPEG-2 applications include
Stream Machine, GlobeSpan, Equator Technologies, and C-Cube (www.streammachine.com,
www.globespan.net, www.equator.com, www.ccube.com). Stream Machine's
SM2201 can both encode and decode video, but not simultaneously
(see "Get maximum pics with minimum bits," EDN, Dec 23, 1999, pg
16), whereas iCompression's iTVC 15, now marketed by acquiring company
Globespan, simultaneously encodes and decodes both audio and video
(see "Audio and video, decoding and encoding ...," EDN, May 11,
2000, pg 28). Vweb's upcoming VW2010, due to become available for
sampling in the second quarter, will offer similar capabilities,
and future chips will target MPEG-4.
C-Cube's
similarly priced DVxcel is also a video-only chip, but it simultaneously
encodes and decodes (see "Cost-compressed codec targets VCRs," EDN,
Feb 3, 2000, pg 26). C-Cube's $29 published price, however, requires
a significantly larger order quantity than does Vweb. Media processors,
such as Equator Technologies' MAPCA-2000 claim, at least in their
controlled-environment demos, to be able to tackle encoding, decoding,
and system-control functions in a single chip (see "Compression
puts images on a diet," EDN, June 18, 1998, pg 71). Media processors
can also support nonstandard codecs, such as wavelets (see "Wavelets
both implode and explode images," EDN, Dec 21, 2000, pg 55), but
you may not need or be willing to pay for that flexibility.
Vweb Corporation
is headquartered at 5300 Stevens Creek Boulevard; Suite 320, San
Jose, CA 95129, E-Mail: info@vwebcorp.com and on the Web at www.vwebcorp.com.
CONTACT: Vweb
Corporation, San Jose Bill Reckwerdt, 408/615-1888 ext. 219 billr@vwebcorp.com
or e21corp Marti Miernik, 510/226-6780 ext. 174 (Media Contact)
marti_miernik@e21corp.com
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