While listening to a discussion on this subject at a recent video club meeting, I realised that this concept sometimes poses problems for those beginning to edit their videos. Hence this short – and hopefully enlightening - explanation.

In general usage, animation in editing means ‘making something change over time’ and is not necessarily restricted to e.g. animating a cartoon character, although here again, you are making something ‘change over time’.

In the credits in a movie, where the text is rolling off the screen, that motion is the result of ‘animating text’. When one video clip fades out (that is, it becomes less opaque) and the next one fades in (going from transparent to opaque) that is animating the opacity of the clip.

It is keyframes that contain the instructions to the editing program that enable it to animate - or apply these progressive changes - to the subject clip.

Keyframing can be applied to any feature of a video clip which can be changed. This includes things such as opacity, position of the frame (within the viewing space), scale, rotation and the application of various filters/effects such as colour, brightness. Indeed effectively, it is keyframes that are used in audio in cross fades and fade in/outs.

Obviously for a change to occur, there must be a starting point and an end point.

The first keyframe describes/defines the starting parameters, that is where the frame is in the viewing space, its opacity, its angular position in regards to rotation, its scale etc. However, since all these parameters are in the default position to start with, you usually don’t need to touch most of these for the first keyframe. An exception to this would be having something– say, an aircraft – appear to come into view from the distance, enlarging from invisibly small to visible size as it approaches the viewer. Here, you would set the scale to zero at the first keyframe.

The keyframe describing the endpoint of the change is a different kettle of fish. As our aircraft approaches the viewer, increasing in size as it does, the scale parameter might be set to 200% at this point. If the aircraft is to barrel roll five times over the duration of the clip, then the rotation setting at the end keyframe might show something like “5 x 0 degrees” meaning 5 rotations and finishing in the vertical position.

If you desire any deviation from a simple progressive change in the effect from the clip’s beginning to its end, then you can insert an intermediate keyframe at any point along the clip’s duration with additional ‘instructions’ to the program. The software will interpolate (calculate and apply the changes needed) through all the intervening video frames so your master piece will get the effect that you require.

The white diamonds in the grey bar above signify a keyframe where some aspect of the video such as brightness, opacity other effect  is to be changed.

By Frank McLeod

Dr Frank McLeod is a specialist physician who in his ‘day job' works in the area of Addiction Medicine. Frank reckons he ‘dribbled' into video as a way to get information across to his patients and their families in an accessible way that avoided information overload. From there, the monster just grew. With a long-time interest in things technical and gadgetry of all kinds, he had been writing tech review-type-articles on a casual basis for a medical publication for some time, when an introduction to David Hague led to his continuing this level of activity in the field of video.

Frank says that one of the parts he likes best about his involvement with Australasian Camcorder is the opportunity to play with other people's toys. The downside, he says, is having to give them back at the end of ‘playtime' that precedes publication of the resulting review.

"I suppose I want to present information from the non-professional point of view, which is not difficult, given that I am the only amateur punter in the camp," he says. With a strong commitment to the amateur video club movement, he is the Secretary of his local video club. In part because of this, and with a long time history as an avid DIY-er behind him, Frank has an interest in the do-it-yourself construction of devices for the amateur videographer and strongly wishes to continue this type of contribution as part of his future involvement with auscam