Tuesday, July 11, 2006

What is Digital Video?

Digital Video 101
What is the DV format?

Although "DV" technically stands for "Digital Video", DV normally refers to a specific video format. Its specifications include a 5:1 signal compression ratio, a 4:1:1 color sampling ratio, 720 x 480 pixel resolution, 25 megabits-per-second (Mbps) data rate and a general overall picture quality quite similar to BetacamSP.

What about DVCAM and DVCPRO? DV (sometimes called MiniDV to help differentiate it), Sony DVCAM and Panasonic DVCPRO all have the same picture quality, as they all use the same DV video signal format. DVCAM and DVCPRO tapes are larger, can hold longer tape lengths and move faster through the camera during recording (which renders the tape less susceptible to noticeable playback errors from wear-and-tear damage). Because the DVCAM and DVCPRO formats are targeted at more professional users, these cameras typically sport better optics and accessories (and a higher price tag) than most MiniDV-format cameras.

What's the major advantage of shooting in DV? Not only does DV look good, it's also completely digital. This feature allows you to edit your footage (either deck-to-deck or by using a nonlinear video editing workstation) without any loss in picture quality. Typically, analog formats such as VHS and Hi-8 lose significant quality after repeated transfers/duplications; DV does not suffer this problem.

Are there any disadvantages to using DV instead of other video formats? Only if you're comparing DV to higher-end digital video formats (including Digital Betacam, D-9, Digital-S, D-3, D-1, HDCAM and so forth). These formats are not compressed 5:1 and are therefore capable of a better-looking picture (in the hands of an experienced camera crew, of course).

What's the difference between a 1CCD and 3CCD DV camera? Cameras with one CCD (charge-coupled device) rely on a single sensor to capture light patterns from all three primary video colors (red/green/blue). Cameras with 3CCDs utilize one sensor per color, however, and are therefore able to produce noticeably higher-quality images. You will most likely find a steep price division between 1CCD and 3CCD cameras (of any video format type).

What is the shooting ratio?

The shooting ratio of a film or video is the ratio between the total duration of its footage shot and that which results from its final "cut". A film with a shooting ratio of 2:1 would have shot twice the amount of footage that was used in the film. In real terms this means that 120 minutes of footage would have been shot to produce a film of 60 minutes in length.
Shooting ratios can vary greatly between productions but a typical shooting ratio for a production using film stock will be between 6:1 and 10:1, whereas a similar production using video is likely to be much higher. This is a direct result of the significant difference in price between video tape stock and film stock and the necessary processing.

Video and Film Vocabulary

Video and Film Terms that may be helpful from the Internet

Using these terms will help you to analyse and explain moving image sequences in film, television or advertising.

Camera Terms:
What’s included and excluded in an individual shot.

Very long shot/wide shot
A shot in which figures appear small in the landscape. Often used at the beginning of a film or sequence as an ‘establishing shot’ to show where the action is taking place; also used to make a figure appear small or isolated.

Long shot
A shot in which a figure can be seen from head to toe.

Medium shot
Shows the figure from approximately the waist to the head. In a mid shot, you can easily recognize an individual but you can also see what they are doing with their hands.

Medium close up
From chest to head

Head and shoulders, enabling you to easily see facial expressions, so you can see what characters are thinking and feeling

Big close up
Head only, used when expressions are important

Extreme close-up
From just above the eyebrows to just below the mouth, or even closer: used to emphasise facial expression or to make the subject appear threatening.

Other useful terms for shots are:
Two Shot
Any shot with two people in it

Point of view shot
A shot from a character’s point of view

Reaction shot
A shot showing a character’s expression as they react to something

A type of reaction shot used in interviews, where we see the interviewer apparently reacting to the interviewee

Over-the-shoulder shot
A shot in which we see a character over another’s shoulder, often used in interviews or dialogues

Depth of field
This means how much of the shot seems to be in focus, in front of and behind the subject.

Deep Focus
Everything in the shot appears to be in focus, which means that we can be looking at action taking place in the foreground, middle ground and background.

Shallow focus
Isolates the subject from the background.

Camera position
Where the camera is in relation to the subject.

Low angle shot
The camera points upwards, usually making the subject or setting seem grand or threatening.

High angle shot
The camera looks down, making the subject look vulnerable or insignificant.

Bird’s eye shot
Looks vertically down at the subject.

Camera movements:
Moving the camera itself towards or away from the subject, or to follow a moving subject. (Not to be confused with a zoom, where the camera’s lens is varied to give the impression of moving closer to, or away from the subject.)
Pivoting the camera to the side to scan a scene or to follow a moving subject.
Whip pan
A sudden, fast pan.
Pivoting the camera vertically up or down.
Moving the camera in an arc around the subject.
Crane shot
A shot where the camera itself moves up or down.
Hand-held shot
This is used to convey a sense of immediacy.

How the individual shots are put together.
There are two main types of editing which you will encounter in mainstream films and TV programmes:

Continuity editing
The majority of film sequences are edited so that time seems to flow, uninterrupted, from shot to shot. Within a ‘continuity editing’ sequence, only cuts will be used. Continuity editing can also involve ‘cross-cutting’, where a sequence cuts between two different settings where action is taking place at the same time.

In montage, different images are assembled to build up an impression. This is often used in title sequences. The most famous example of this technique is the Odessa Steps sequence from Battleship Potemkin.

Editing can vary both in pace (how long individual shots stay on the screen for) and in the transitions between shots.

Transitions describe the way in which one shot replaces the previous one:

One image is suddenly replaced by another, without a visible transition.

One image dissolves into another. This can be used to make a montage sequence - eg the title sequence - flow smoothly; it can also be used in continuity editing to show that we have moved forwards in time and/or space.

Fade up
An image gradually fades in

Fade out
An image gradually fades out.
Fades to and from black usually mean that time has passed

One image replaces another without dissolving, with the border between the images moving across or around the screen.