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Real Needs, Real Questions, in Real Time

Related Links

“Canopus
DVStorm Review”

“Pinnacle
DV 500 Review”

“Matrox
RT/2000 Review”

For the past year I’ve been reviewing realtime NLE products priced
at less than $2,000. I’ve covered the Matrox RT2000, now replaced by
the RT2500; the DV500 from Pinnacle Systems; and Canopus DVStorm. Since
this series began, I’ve received a steady stream of email asking me
which product I “really” think is best. This email has been
difficult to answer.

All the products deliver capabilities that match and even exceed
those offered by previous M-JPEG products that cost more than $15,000.
So all the boards represent a major advance in price-performance ratio.
Nevertheless, my cynical side reminds me that what allows them to be
called “realtime” is left to the discretion of each
product’s marketing department. Thus, my response to the question
asking which is the best has always been, “It depends on what you
need done in realtime.” Frankly, though, I’ve always felt my
answer to be a bit lame because potential buyers often lack the
background knowledge to compare the marketing claims with their editing
needs.

So if you have trouble sorting out marketing claims and
counter-claims, read on. I present eight realtime functions that a
given product may or may not support. As I do this, I comment how vital
these functions are for my needs. While these comments may not apply to
your needs, they should inform you in your own decisionmaking
process.

Transitions

All realtime products offer a collection of 2D transitions.
Collections include dissolve, plus a set of wipes and tiles. I use
dissolves but don’t find wipes and tiles aesthetically useful. If you
do use wipes and tiles, be aware that products differ in their support
of border color and border blur. Moreover, products that support edge
effects do not do so consistently for all realtime wipes.

Only the Matrox RT2500 supports realtime 3D transitions. If you need
3D effects, that’s the product you want. Both the DVStorm and DV500
Plus are bundled with a Premiere plug-in that renders 3D transitions.
Canopus also offers software that uses nVidia-based graphics boards to
accelerate 3D transition rendering. If you don’t employ many 3D
effects, these options may be acceptable. However, I’ve found that once
you get used to having realtime 3D effects, it’s very hard to live
without them.

Filters

Filters creatively alter the look of video and adjust image
properties, such as color correction. There are several methods of
making image adjustments.

HSB (hue, saturation, and brightness) controls let you adjust hue
(rotation of I and Q phase to correct for chroma phase errors) plus
chroma-level (saturation) and luma-level (brightness). RGB controls
allow individual adjustment of the three primary color levels. And YUV
enables adjustment of the level of each video signal component.

Only DVStorm offers all three types of control. The DV500 Plus
cannot adjust hue, and the RT2500 can make only RGB corrections.
Although all products allow adjustment of black and white levels, I
consider gamma adjustment to be of far greater value. In this category,
all of the products strike out.

Using keyframing, filter parameters can vary dynamically over the
duration of a clip. The DV500 Plus, however, allows only start- and
end-of-clip keyframes — often all that’s necessary. All products
set, adjust, and delete keyframes from a pop-up window supplied by the
board maker. I would much prefer software where keyframes could be
placed directly into (and across) clips from the timeline.

DVE

A DVE can be generated by either the CPU (DVStorm) or a high-speed
graphics chip (RT2500). A DVE is applied to a clip through the use of a
video filter. A 2D DVE can also be used to upscale letterbox-cropped
4:3 video to anamorphic 16:9 — or to downscale anamorphic 16:9 to
yield letterboxed 4:3 video. An RT2500 DVE can be used to animate video
and graphic clips in 2D or 3D space. When applied to textual graphics,
very dramatic, dynamic titles can be created. Unfortunately, Premiere’s
sophisticated Motion Effect capability is not supported by any board’s
DVE engine.

Compositing

All realtime boards offer alphakeying for compositing graphics over
video. And all but the DV500 Plus offer luma- and chromakeying. Because
I’ve never had much luck getting clean composites, the DV500’s
shortcoming is not important to me. Premiere itself makes compositing
difficult because when you adjust critical key parameters, the
composite is visible only in a tiny window on your RGB monitor.

Titles and graphics

With today’s graphics-filled video productions, it’s important that
a still image can be placed into a timeline without the need to render.
Equally important is the ability to apply realtime effects to
transition from one graphic to another. Premiere can’t do this because
it allows only .avi clips in track 1. Matrox overcomes this limitation
by supplying a utility that batch-converts .tga graphics to .avi clips.
If you use StormEdit rather than Premiere, the DVStorm can perform
transitions between graphics.

Titles are superimposed over video using an alphakey. Ideally the
titles should autokey when placed in a timeline. If autokey is not
supported, you’ll need to apply a Transparency alpha-filter to the
title clip.

While all products create static titles, only the RT2500, using its
DVE generator, and DVStorm create dynamic realtime rolls and crawls.
The DVStorm can generate multiple titles over video — each
differently animated. Only simple paths can be defined, however.

Export to DV tape

The topic that generates the hottest debate is whether a DV-oriented
product can really be called realtime if it cannot record a timeline to
DV tape — over an IEEE-1394 connection — without rendering
realtime effects. Until recently, I felt that if creative editing could
be accomplished without rendering, the product was realtime enough for
me. Because all of these products can playback supported realtime
effects to the RGB monitor and to an analog VCR/monitor without
rendering, all meet this requirement. (Interestingly, so does the
inexpensive Canopus DVRaptor RT.)

I’m now less patient. If one employs only brief transitions in a
production, it may be acceptable to get a cup of coffee while the
transitions render. However, when almost every shot has been
color-corrected, I’m not willing to wait for the entire production to
be rendered.

But the issue is not simply render time. The RT2500 requires all
realtime effects be rendered, after which the timeline is
“compiled” to disk. Compilation copies all source and
rendered clips to a temporary file that is then output via IEEE-1394.
While copying clips is much faster than rendering, I feel compiling is
a waste of time and, more importantly, disk space.

The DV500 Plus does not require a compile, but like the RT2500 does
require effect rendering prior to DV recording. The DVStorm, however,
never requires a timeline that can be viewed in realtime to be rendered
or compiled prior to DV recording. But note the phrase “a
timeline that can be viewed in realtime.” With the RT2500 and
DV500 Plus, if you follow the “rules of realtime,” your
timeline should be able to play in realtime. These rules prohibit, for
example, more than two .avi streams playing simultaneously with one
realtime effect between them.

There are no realtime rules with the DVStorm. While that’s
liberating, a timeline may or may not be viewed in realtime without
rendering. It all depends on the power of your computer. If the
timeline can play, you can record it to DV. If not, you’ll have to
render areas of the timeline that cannot play perfectly before
exporting to DV.

The DVStorm can export to DV without rendering because it uses
software codecs (rather than an MX25 chip) to decompress the video
stream(s), while an onboard hardware codec performs realtime
recompression. The unique design of this product also enables more than
two video streams to be uncompressed in realtime — a task neither
of the other products can perform. But you do need a truly powerful
system to accomplish this.

So really, which is best?

If I’ve done my job, you now have a list of questions to ask anyone
trying to sell you a realtime product. But first, in the chart above,
you might want to circle “yes” or “no” answers
to define those functions you need performed in realtime.

A quick glance at the chart will tell you that none of the three
products examined in this story offer all capabilities. That’s
unfortunate if you need these capabilities and must purchase now,
because you’ll have to compromise. But it also means that all of the
companies will continue to add missing features as they compete for
your future business.

Contributing editor Steve Mullen is owner of Digital Video
Consulting, a company that conducts seminars on digital video
technology. Mullen can be reached at d-v-c@mindspring.com. His website is www.mindspring.com/~d-v-c.

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