Thanks Dave. Isn't there simultaneous decode, at least on a macroblock basis? It's not too relevant to the original DVD-RAM question. Desktop video news..................
techweb.cmp.com
PCs improve their images
By Stephan Ohr
ANAHEIM, Calif. -- With Internet video, CD-ROM playback and
videoconferencing becoming more common, users can forget that the display
of video on a computer graphics screen requires specialized hardware and
software. The horizontal-scan rates for consumer televisions defined by the
National Television Standards Committee (NTSC) are different than the scan
rates required by computer monitors. Special talent is required to ensure that
video doesn't drop frames or appear grainy on the computer screen. That's
the thinking behind many video products that will be introduced and
demonstrated at the TeleCon XVII conference here this week.
Lucent Technologies' Business Communications Group (Basking Ridge, N.J.)
demonstrated new conferencing servers. Video codec maker Zydacron Inc.
(Manchester, N.H.) demonstrated a PC-based videoconferencing system
based on Lucent's AVP III chips. And Motorola Inc.'s Semiconductor
Products Sector (Austin, Texas) unveiled its videoconferencing codec chips.
Elsewhere, Texas Instruments Inc. (Dallas) announced a new generation of
NTSC encoders and decoders--the kind that fit hand in glove with high-end
3-D graphics accelerators.
The desktop-videoconferencing market, to which many of the TeleCon
product introductions were addressed, looks like the virtual hockey stick on
a plot of unit shipments (and of sales dollars) over time. A period of slow
growth and acceptance is followed by sudden and rapid growth to create an
almost vertical slope on the graph. Unit sales of expensive ISDN and
cable-modem conferencing systems are showing steady increases, but the
rapid growth that manufacturers are looking for will come, many analysts
believe, with the announcement of affordable high-quality systems for analog
POTS lines.
Andrew Davis, an industry consultant who tracks the videoconferencing
market, believes that 20 to 30 million units that embody H.323, the ITU
POTS conferencing standard, could be shipped in the year 2001. But this
number is contingent on the availability of affordable PC-based
conferencingsystems of acceptable quality. The cost goal, said Davis, is a
videoconferencing package with a camera, an insert card and software that
carries an OEM price under $120. Too many systems, he said, show grainy
pictures with stuttering video at rates of 5 to 15 frames/second.
Many of the disparate TeleCon introductions can be understood by how they
position themselves around this target. Zydacron is targeting the high-end
corporate executive and small-business user, rather than the general
consumer. It will compete with PictureTel Corp. and 8x8 Inc., each of which
offer complete videoconferencing packages. Motorola is targeting its
DSP-based chip set toward the general consumer conferencing market, but
will confront severe pricing pressures and competition from DSP chip makers
Lucent and 8x8. Cost-conscious Texas Instruments' NTSC/PAL encoders
and decoders are targeting the convergence of PCs and consumer television.
And Lucent's $74,000 conference server is geared toward MIS and PBX
system managers looking to supplement the conferencing capabilities of their
internal networks.
Zydacron's OnWAN350 videoconferencing system is intended for use on
ISBN-BRI or T1 phone networks, and will deliver 30 frames/s of video at
QCIF (176 x 144 pixels), or at higher resolutions with slower frame rates.
Zydacron's TeleCon demos, in fact, included transmitted medical images
from an operating room. "There's not too many systems that can give you the
details of a surgery," said Ed Govoni, vice president of marketing for
Zydacron.
Though the OnWAN350 is targeted at high-end applications, Govoni said it
should be "as easy to use as a telephone." The system includes a PCI board,
a camera, microphone, cables and software for Windows 95. The package
includes the OnWAN application software, as well as Microsoft's
Netmeeting, DirectX drivers and Internet Explorer 4.0. It lists for $1,995 and
is available now. A Windows NT version will be available early in 1998.
Motorola will reveal a two-piece chip set for video this week. Called the
Qorus videoconferencing system, the chips include the DSP56303--a version
of the 56000 DSP--and the MCQ70, a video-compression accelerator. By
putting the motion estimation and discrete cosine transform (DCT) on a
separate chip and letting the DSP worry about protocol dissection, the set
encodes and decodes QCIF pictures fast enough to allow 30 frames/s video
on analog POTS lines, said Steve Sperle, multimedia marketing strategist for
Motorola. The chip includes software drivers for H.320 video graphics,
H.323 Internet protocols and H.324 POTS transmission standards. It also
supports T.120 "white board" sharing, and data-transmission rates up to 384
kbits/s.
Motorola believes this product could finally stimulate rapid growth of the
desktop videoconferencing market, but it will not reveal pricing until the chips
start sampling in 1998. But Motorola said its videoconferencing chip set is
"right in the range of what's out there now," according to product manager
Ron Grigsby.
A reference design will also be available for the chip set, Grigsby said.
Motorola is shouldering its way into a market that's already carved up by
Lucent Technologies (Berkeley Heights, N.J.) and 8x8 (Santa Clara, Calif.).
DSP chip makers like Texas Instruments and Analog Devices Inc.
(Norwood, Mass.) have already shown reference designs for
videoconferencing, Davis said.
Meanwhile, Texas Instruments is thrusting its newest product introductions
into an NTSC/PAL encoder market already carved up by Philips and the
Brooktree subsidiary of Rockwell. TI's TVP5010 NTSC/PAL decoder
converts analog video inputs into digital video for a graphics controller, and
its TVP6000 NTSC/PAL encoder converts digital video into analog. The
special advantage of these chips, said John Reder, marketing engineer for
TI's multimedia products, is the image quality and stability provided by dual
comb filters in the decoder, and the flicker filters and overscan compensation
in the encoder.
In operation, the video decoder converts NTSC or PAL video signals into a
YCbCr color space that is used to display video scan lines as pixel-dot
information on a color graphics computer screen. The comb filter is used to
separate luminance (brightness) and chrominance (color). Without these, said
Reder, cross-color effects--where the decoder interprets picture information
as color, and vice versa--can occur. This can be seen as shifting moir_
patterns in, for example, striped clothing and objects. Bandpass filters can
eliminate video cross-color effects, but can also make the video image dark
and shadowy. Comb filters, on the other hand, minimize video cross-color
effects while maintaining full luminance bandwidth.
Overscan compensation in the encoder, meanwhile, scans a television image
to provide all the detail ordinarily seen on a computer monitor. The computer
monitor uses a progressive scan, Reder said, while the television is interlaced.
Without overscanning, the television will miss the outer edges of the computer
screen, such as the 'Start' button bar on a Windows 95 screen.
The TVP5010 and 6000 are designed to interface with advanced computer
graphics controllers, like the TVP4020, which was jointly developed by TI
and 3Dlabs. The 4020, said Reder, includes a video port which displays
NTSC-decoded video in a window on the computer graphics screen or on a
full screen, if required. While not specifically designed to do so, the 4020 will
support DVD playback and videoconferencing sources, said Reder. This
capability will be demonstrated by TI at Comdex next week.
The TI encoder/decoder parts are each packaged in an 80-pin thin quad flat
pack. Samples will be available this quarter, and volume production is
scheduled in the first half of 1998. The TVP5010 decoder is priced at
$15.35 each and the TVP6000 is priced at $9.95 each in 1,000s.
Separately, Lucent Technologies unveiled its audio conference server is
based on the Consortium conferencing system of Coherent Communications
Inc. The server requires callers to connect through a 'meet-me' dial-in
number, and is designed to offload conference calls from PBX systems and
corporate phone networks. It supports up to 96 participants in single or
multiple conferences. It runs a PC running Windows 95 or a LAN-based PC
running Windows NT 4.0. |
