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What is digital video editing? Is it different from
nonlinear editing?
How do you create digital video
for editing?
How does DV editing work?
What is rendering?
What is the difference between
DV, Firewire, and iLink?
How do I edit using DV from a DV camcorder?
Computer-based editing systems versus black box. Which is better?
Macintosh versus Windows. Which
way to go? Build it
myself or buy a pre-configured system? What
kind of camcorder do I need? How
long should my videos be?
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What is digital video editing? Is it different from
nonlinear editing?
Digital editing is simply editing a digital version
of video rather than an analog version. Instead of using a tape based
analog medium to store the info, you are using digital bits and bytes to
store the video and audio. Some
call it desktop editing, some call electronic editing, some call it NLE
or nonlinear editing. Regardless of what you call it, it is all
basically the same. The differences are flexibility and quality.
Because you are not actually playing and recording
scenes onto a new tape, you can easily and quickly try out different
editing patterns. You can try out one series of scenes for your
production. If you don’t like it, you can move them around and try out
a different series. You can add in new scenes or take out ones that do
not work. With an analog tape based system, you would have to start from
scratch, re-laying the scenes down on the tape each time you made a
change.
Digital editing also improves overall image
quality. Because you are using a digital format, making changes and
copies does not result in generation loss – you are simply copying a
digital representation of the video. That is unless you do a lot of
signal compression, decompression and re-compression. More on that
later.
How do you create digital video
for editing?
It always starts with video captured by a
camcorder. If you are using an analog type of camcorder like a VHS or 8m
camcorder, your video and audio footage has to be converted into a
digital format such as MPEG or MJEG. The video has to be converted from
an analog representation (sort of like the groves in a vinyl record) to
a series of digital 1s and zeros. There are a bunch of hardware
solutions that can do this. These digital capture cards can be inserted
in your computer. Prices start at $50 each and go up to the thousands,
depending on quality, bandwidth, features and bundled software.
If you do not want to open up your computer to
install capture card, you can use a MPEG peripheral device such as the
Dazzle Digital Video Creator. You plug your analog video (S-video or
standard) into the box and then the MPEG digitized video flows over a
USB or parallel cable into the computer.
By the way, you do not need to playback from tape.
You can plug your camcorder or video camera into your computer or MPEG
device and capture it directly to the hard drive, eliminating tape.
Unfortunately, unless you are using a small portable notebook computer,
this limits your videotaping mobility.
As part of the hard drive capture process, the
digitized video needs to be compressed and made smaller. Raw video
streams out at 30 megabytes a second or more. That is a lot of data and
most of computers and hard drives cannot handle that flow. By using a
variety of compression technologies, the video throughput can be
shrunken by a factor of 3 to 1 to 100 to 1. In general, the more you
compress your video, the more you reduce your quality. However,
compression rations of 3 to 1 and 4 to 1, usually do not create
noticeable loss.
Compression
technologies work by analyzing the video stream and assessing which
video information can be left out and eliminated. For example, if you
have a person standing in front of a blue wall, the technology
recognizes that the blue wall is uniform in color and is not changing,
Therefore it can be compressed a lot more than the person who is
talking.
There are a wide range of different compression
technologies including QuickTime, Motion jpeg (M-JPEG), MPEG1, MPEG2 and
the new MPEG 4. Confusing the issue is that a technology such as M-JPEG
may have various different codecs (short for COmpression-DECompression)
that actually do the compression and decompression of the video and
audio. Various codecs may not talk to each other.
Once the digital video has been compressed and
captured onto your computer’s hard drive, editing encompasses two
basic functions – database management and rendering. The database
management aspect means keeping track of where your various scenes are,
how long you want them to be, and then in what order you want them to
play back in.
For example, when you trim a scene – figuring out
where the scene begins and ends, you are not really changing the scene
at all. You are simply telling the editing software’s database to keep
track of these new video locations and use them when playing back the
video. This is why it is easy to change your clip in’s and out’s as
well as to create alternate trims of the same clips. When you edit your
video together, the database then keeps track of which scene should be
played first, which should be played second, and so on.
If your entire movie consisted only of cuts, the video would not
have to change at all. The database would simply have to keep track of
all the in and out points, as well as the playback order of the trimmed
scenes.
Because it is just a database of play commands –
not an actual video file, it is easy to re-arrange the scenes over
and over again until you get them just right.
What is Rendering?
Depending on your video card, your software and
your computer’s hard rive and bus specifications, you may have to
render the entire movie before watching it back. In other words, the
database is unable to retrieve the scenes fast enough to play back in
real time. Therefore, it retrieves them once by one and electronically
compiles them together into a new, and longer, file that can be played
back all at once. This is how the less expensive systems operate.
Effects and transitions also have to be rendered
and saved to the hard drive before playback for recording – that is
unless you have one of the newer and more expensive “dual-stream”
video editing solutions. To create a transition where two or more video
streams are mixed together – like in a wipe, dissolve or special
effect, the two streams must be uncompressed, electronically taken apart
into their ones and zeros, temporarily stored in RAM, mixed back
together, and then compressed again, creating a new digital file. This
happens frame by frame. This
process takes time and lots of computer horsepower.
A dual stream solution essentially functions as two
separate computers – each handling these series of functions and
enables real time or close to real time creation of effects and
transitions. Depending on your dual stream system, the commands for
these effects can be stored in a database and only implemented upon
final playback to tape. Otherwise, the effect can be created in real
time and rendered directly to the hard drive, to be later called up upon
playback.
What is the difference between DV, Firewire, and
iLink?
Not much. Theoretically,
all are based on the IEEE1394 standard for digital video. However, in
the real world, various manufacturers have tweaked the spec slightly for
their own models. Luckily, these tweaks mostly have to do with power
issues and transport controls for the camcorders. By the way, there are
new versions of 1394 destined to hit the market soon with much higher
throughout capabilities.
iLink is a term used by Sony; Apple likes Firewire,
and the rest of the industry uses DV or 1394.
How
do I edit using DV from a DV camcorder?
DV is captured onto tape in a digital format. Therefore, unlike analog
formats like VHS and 8mm, DV does not need to go through a digitization
process to be captured onto the hard drive.
In addition, DV is already compressed by using a variety of
technologies built into the IEEE1394 standard. Many computers, including
most new Apple G4s and Powerbooks, include a Firewire adapter built in.
Many new Windows computers are also arriving with built-in Firewire/1394
adapters.
There are a
variety of 1394 adapter cards on the market that can be installed with
your computer. Once again the price ranges, starting at about $50 and
going up from there depending on the card's performance, features and
bundled software package.
Computer-based editing systems versus black box. Which is better?
Black Box editors like Applied Magic’s Screenplay and DraCo’s
Casablanca are essentially computers in a box with all the required hard
drives, software and processing hardware included. Most computer
hardware and software solutions are available for both Macintosh and
Windows computers. These start at $1500 and go up from there.
The advantage of using a black box editing solution is that you do not
have to share it with your other computing tasks. There is much less
chance of it crashing because you installed a bad program or caught a
virus. Black boxes are harder to re-configure and change – this
prevents you from screwing things up by experimenting. In addition,
black boxes are usually much more portable than desktop video editing
systems. About the size and shape of a VCR, all you have to do is hook
it up to your TV set or monitor and you are ready to edit. Once your
video is digitized onto the black box’s hard drive, you can edit your
videos anywhere – in the living room, the garage, or out on the patio.
Both DraCo and
Screenplay include options for editing DV, as well as bring in graphics,
still images and titling.
The advantage
of a computer-based system is more power and choice of software,
effects, graphics and titling. If you already have a powerful computer,
doing video editing may only cost a few hundred more for the new boards
and software versus $2,000 or so for the entry-level black box products.
Macintosh versus Windows?
I am not going to touch that on for fear of starting a flame war.
Suffice it to say that there are good solutions for both
platforms, and personally, I use both.
Going out on the limb
for the beginner, the new Macintosh G4,
iMACs and Powerbooks are very powerful and include a built-in
Firewire converter. In addition, Apple’s iMovie software is free and
enables the video editing beginner to get a quick and easy start. All
you need is your DV camcorder and a Firewire cable (4 pin to six pin).
Should I buy a pre-configured system from a video
dealer or assemble it myself?
This is another loaded question. For beginners, I would recommend
assembling a system together. It
is quite simple to put together a basic system. By assembling it
yourself, you may save money and learn the ins and outs of your system.
However, if you are
starting a business and want to quickly start generating cash with a
minimum of downtime, I recommend using one of the dealers who will
assemble, deliver and set you up with a powerful pre-configured digital
editing system. I am on several Internet mailing lists consisting of
video professionals who use this stuff on a daily basis. Most of them
are techies and have assembled their own systems. Despite their wealth
of knowledge and expertise, I find that they are always discussing new
challenges to the hardware and software set-ups.
What kind of camcorder should I use?
You can use any type of camcorder as long as it has some kind of video
and audio output connection. If you are using a VHS, S-VHS, 8mm or Hi8mm
camcorder with analog outputs, you need a computer editing system that
can accept analog video and audio and has the matching connectors. Most
editing systems, especially the less expensive consumer and prosumer
cards, use standard RCA plugs. Most analog cards also include a S-video
connector for connecting to s-video camcorders. However, these are still
analog recording units. The process of capturing and playing back and
analog signal from tape results in a 10 to 20 per cent loss in
resolution and quality.
I recommend using a DV camcorder. The prices are dropping quickly. By
using a DV camcorder, you have the choice of using either an analog or a
DV card in your computer. For example, if you already have a M-JPEG
capture card, you can input high quality video from the camcorder’s
analog outputs. DV camcorders excel by enabling you to record the video
in a digital format on the tape. When played back through the DV
Firewire connector or via the analog connectors, the video still looks
great.
For example, my
Apple G4 has a Firewire jack. My Pentium computer has a Matrox MJPEG and
a Vitec MPEG capture card inside. Both of those cards use standard RCA
and S-video analog connectors. When I want to digitize video I have a
choice. Moreover, to tell the truth, I cannot see much difference
between the raw video played from the DV connector versus the S-video
analog connector even thought there is an additional decompression step
required for the s-video playback.
They should be as long as they need to be. Some of the first editing
systems required actually digitizing and rendering the entire movie
prior to playback. Sometimes this forced you to come up against the
Windows 2 gig limit for continuous files. Most of today’s data-based
programs simply play back a series of shorter files one after another,
to avoid that problem. However, despite that, the shorter and more
concise your movie, the better your audience will appreciate it.
When I went to film school, my teachers taught me a rule of scene
length. You see the scene, you see what happening, now move on to the
next scene.
Check out Doug
Dixon's Digital Video Editing Software Gallery
Software applications
for digital video editing (and some with DVD authoring), organized from
consumer to professional. Each application includes a brief description,
and information on the latest released version. Product descriptions and
images are summarized from published information.
WEB INFORMATION:
Apple Computers www.apple.com
Applied Magic Sequel
and Screenplay Black boxes www.applied-magic.com
Canon Camcorders www.canon.com
Digital Origin
editing systems for Mac and Windows www.digitalorigin.com
DraCo Systems Avio
and Casablanca Black Boxes www.draco.com
Dazzle MPEG Devices www.dazzle.com
Matrox Digital
Editing boards www.matrox.com
Sony Computers &
Camcorders www.sel.sony.com
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