Learn the two different methods of how video frames are created, and how to determine the right setting for your project.
“VIDEO” is really just a collection of still frames that are captured, which can then be played back back fast enough to create motion video. There are two methods in which these still images, or frames as they’re referred to in video, are captured. Interlaced and progressive. But just what do these two terms mean, and how does it affect your footage and your workflow? Let’s start with the easiest to explain, progressive video. Progressive video captures an entire image at one time, and this creates a single frame. Those whole frames are then played back in succession to form motion video. Capturing frames in this method has many advantages. It’s easy to integrate visual effects and motion graphics, you can pull still frames from your video, and all video on the web is displayed as progressive, regardless of it’s original source. Interlaced video creates a “frame” by using 2 fields. Each field captures half of the image at a given point in time. The odd field captures every odd horizontal line, then the even field captures the remaining lines. Each field is taken at a different point in time, typically about 1/60th of a second apart, but they are played back in alternate fashion so quickly that our eyes perceive it as one complete image, ignoring the fact that at any given time, only half the lines are actually present. The main advantage of the interlaced method is you can keep file size and bandwidth low, while still capturing enough information to get smooth motion from fast moving action or camera moves. Unfortunately, there are some drawbacks to using this method. If you try to stop on an individual frame on interlaced video, you’ll see what’s called the combing effect especially when there’s fast motion in the scene. This results from the odd and even lines you’re seeing being taken about a 60th of a second apart. If your final destination is a progressive screen, you’ll either be stuck showing this combing effect, or you’ll have to deinterlace your footage, which results in reduced resolution and sharpness. We’ll allow you to draw your own conclusions as to which method works best for your project. But for the record, we’ll always be shooting progressive.
