Video compositing is a process of combining multiple layers of video with each other or visual/graphical elements. Like with a composite image where you add layer on layer it is that process but done with moving image.
Image from: http://www.haunteddimensions.raykeim.com/layerdiagram.jpg
Video compositing is used everywhere it is used in news when it gives you the latest news this is called lower thirds. It works the same as a composite image where you have the video in the back, then you have the coloured box over the top of that, then you have the text over the top of that.
Image from : https://i.ytimg.com/vi/q3GOjOCvZBA/maxresdefault.jpg
A more complicated video compositing is shown the design film festival by Sebastian Lange. At 15 seconds you can see that he has had to use multiple layers. Langue has started of with a background which is a very blurry video. He then has used a mask and put the video inside the A. He has then done the same thing with the R but has used layers and put the R in front of the A. He has then done this again with the T. He has then used another layer to put the text on . A good and interesting technique he has used is that when the text is moving when it comes off the R it changes colour so you can see it on the background he has done this by using mask again.
Some different techniques used in video compositing are-
Mask – These are attached to the layer.
Matte – These are independent of the layer.
Rotoscoping – Used to remove parts of the layer.
Green Screens/Blue Screens – Used for composting two images or videos together.
A simple way green screens are used are in weather forecast as they put a image behind her on to the green surface.
Image from: http://philgreg.tv/wp-content/uploads/2011/07/weather.jpg
People would want to use video compositing because it gives them the chance to work within layers and you are able to add effects. By doing this they are able to give the video a better look and feel.
According to the website “dummies” video compositing is “when you composite a scene in your digital video, you actually layer several different clips of video over each other to make a single image.” (http://www.dummies.com/photography/video/compositing-video/)