It's the network, stupid!
Remember: The codec sits in the camcorder or VCR! You have already
paid for it. With DV, the video is already captured and compressed.
All you have to do is to copy the digital data to your computer via
the Firewire. This isn't "capture," it's a data transmission.
Think of your camcorder connected to your computer by a high
speed network and you get the idea.
The Firewire interface board in the computer can be quite inexpensive.
Even the first generation Firewire boards coming to market cost less than
$1000. Expect this price to drop rather quickly. Also expect the Firewire
connector to migrate to other peripherals, like a disk controller, or even
the motherboard. Texas Instruments already sells a laptop with built-in
Down to the shirts: The Adaptec/DPS Spark:
Announced for $1000, now selling "naked" for $699.-
High Quality, High
Performance, Low Cost.
High quality: With analog video, noise can enter at any point of
the path. And usually, once noise has entered, noise will stay. There's
tape noise. The cable that routes the video to the capture card can pick
up noise. The capture card usually picks up a lot of noise, because it
sits in a very noisy environment: In the computer. Going back out to tape
adds noise yet again.
Noise doesn't just degrade the picture, it also degrades the compression
process. Because a codec treats noise as information, it dutifully stores
the noise. Which results in high data rates. Those of use who survived
the years of analog video on the computer got used to thinking that anything
better than 5 Megabytes/second or less than 4 tx compression is good.
This is true in most of the cases, but not all. Those of us lucky enough
to own very high quality equipment quickly realized: A very clean video
signal actually lends itself better to compression. It can compressed more,
it can tolerate a lower data rate and still look better. Why? Because it
was free of noise in the first place. By compressing the video at
the point of origin (in the camcorder, behind the lens), DV avoids noise
High performance: Analog video usually compresses at a
varying rate. If the content is complicated, the data rate goes up. Owners
of Premiere can actually watch this process by using a feature called
Movie Analysis. It usually shows spikes in the data rate during complicated
scenes, such as transitions. These spikes can lead to data stalls on playback.
The video zips along nicely, suddenly a spike comes down the pike,
spike exceeds the bandwidth of the computer and bang, playback hangs.
DV uses a steady rate of around 3.7 Megabyte/second. This is a no-brainer
for a moderately fast system with a decent hard drive. There are
no spikes in the data stream, ergo no bumps in the road to good playback.
Low cost: A good capture board can be an expensive thing, and
some of use have amassed quite a collection over the years. As new
ones emerge, driver support for the old ones dries up. Will it ever end?
Yes: Let's forget about capture boards altogether. With DV, capture and
compression happens right behind the lens..