The magazine of the Melbourne PC User Group Cooking Of a Different Type Lawrie Weston

Would you like to GRAB some FOOTAGE from your DV CAMCORDER or your ANALOGUE CAMCORDER, as COMPOSITE, SVHS or DV? Would you then like to EDIT the FOOTAGE and after RENDERING, output it to either TAPE or DISK?

I guess if you know what the above terms mean, you are probably already doing so. A recent query has prompted me to qualify some of the terms we PC Video Editing types use as a matter of course.

All references in this article will apply to Non-Linear editing of videos in a PC. (NLVE)

FOOTAGE
Perhaps in these days of "Metrification" we should be calling our video clips 'Metreage'. (In olden times there were 12 "inches" in a "foot", approx 30.5cm). This old term harks back to the days of film when it was used to describe the length of film on the spools. A reel's diameter determined how many "feet" of film it would hold, and the number of reels determined the total length of film available for editing.

Now we use videotapes and refer to "Minutes" of video held on the tape(s). The collective noun "FOOTAGE", by general usage, refers to all the clips to be used in a project.

GRAB FOOTAGE

Your footage may be on several tapes, interspersed with other material that is not required for the current project. To edit this footage you first have to import the required video into the computer and store it on a hard disk.

For the computer to be able to work on it requires conversion of video and audio information into numbers. (a PC is really just an adding machine).

If the information has already been converted, as in the case of a DV Camcorder (more on this later), then it is simply transferred to the computer, usually via an IEEE1394 connection.

If the Camcorder is Analogue (more on this later as well), there is the requirement of first converting the video and audio signals to a digital form. This can be done by passing it through a DV Camcorder for conversion, or by using a hardware device, usually installed into a PCI Slot in the PC. There are other options but I won't talk about them here, as this is an article on terminology, not editing.

The footage to be edited can come from relevant sections of several tapes, or just the one tape.

ANALOGUE CAMCORDER

I'll start with this type of Camcorder, as it is the oldest form and still the most prevalent: however the tide is changing and most new Camcorders bought these days are DV.

Much like an audio tape recorder stores the pitch and volume of a sound wave onto magnetic tape, Analogue Camcorders store the audio and video signals. (Simplistic, yes, but good enough for here)

There are two forms of video signal storage.

SVHS/Hi8
offers a higher quality picture and records the brightness and colour information separately. These are also known as Luminance (Y) and Chrominance (C). The term "YC" is quite common in reference to this type of signal information.

COMPOSITE / VHS / 8mm
is the standard used by most average VCRs in homes (Video Cassette Recorders)

RGB

Is a method used professionally, which uses three chips, one for each primary colour. Red, Green and Blue. The most usual professional analogue standard is known as "Beta cam"

For editing in computers, analogue signals have to be converted into numbers as stated previously.

DV CAMCORDERS
these Camcorders use the same type of CCD or CMOS sensor chips as Analogue ones, however, the camera converts the analogue information to digital before storing it on tape.

Digital storage offers several benefits over Analogue, the main two being a better signal to noise ratio and no losses when copying.

Whereas there was a noticeable loss of quality when copying analogue tapes, particularly from one copy to another copy, the loss when copying between digital tapes is negligible.

I have seen a demonstration where a DV was copied between camcorder and PC 7 times without detectable loss of quality. An analogue demonstration failed at about the third copy-to-copy (also known as "Generation")

Once the footage is in the computer, it is then EDITED.

Think of a Newspaper Editor, The job of the Editor is to make the information presentable.

Parts will be cut out, some rewritten, Headlines created, text moved from one spot to another etc.

The video Editor does much the same thing. Trimming and reorganising the clips, Adding Titles and background music, Perhaps a commentary, a few TRANSITIONS and so on.

A TRANSITION can be as simple as a cut or fade from one scene to another, or a bewildering array of effects. eg. outgoing scene becomes a box that flies away, leaving the incoming scene.

A finished edit has to be RENDERED. That is, all the bits and pieces have to be converted to one video/audio interlaced stream.

To output to disk, it has to be RENDERED further into an appropriate MPEG Stream.

MPEG stands for the Motion Picture Experts Group who devise compression algorithms (methods of compression) to reduce the size of video files to that which can be managed on a computer.

RENDERING = time That's where processor speed and memory size are significant factors.

Summary

Making a video is a piece of cake

The whole process is like baking a cake:

Reprinted from the November 2003 issue of PC Update, the magazine of Melbourne PC User Group, Australia

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