Working with aspect ratio
When we looked at the Ken Burns effect in Chapter 3, we briefly touched on aspect ratio. To recap, aspect ratio is the ratio of a video’s length to its height. So, for a 16:9 screen, for every 16 pixels (it could be any unit) that we go along the screen, the screen goes 9 up. Different aspect ratios will give a video frame a different overall shape – a 4:3 frame will be taller than a 16:9 frame, so if you overlayed 4:3 footage over 16:9 footage, pillarboxes – which are the sides of the 16:9 video underneath – would show through. You would need to crop the 4:3 video to reduce its height or crop the 16:9 video to reduce its length for the two to fit the same shape of frame.
Aspect ratio examples
To give you an idea of what aspect ratio means in practice, here are some examples:
> The modern HD TV standard is 16:9.
> Old TV shows were shot in 4:3, which is taller than 16:9. This leaves pillarboxes at the side of a...
