ABSTRACT
For starters, video, like animation, is nothing more than the illusion of motion over time. This illusion is achieved by a showing a sequence of still images in fast enough succession to give the appearance of smooth and continuous motion. At one time or another you’ve likely had occasion to play with a flip book, a booklet with a slightly different drawing from page to page. When you flip through the book fast enough, the drawing looks like it’s moving on the page. If you can imagine each page of that booklet as a still frame of a film, the rate at which you flip the pages equates to the frame rate of the movie. Frame rate is measured in frames per second (fps). The higher the frame rate, the more pages get flipped per second, and, consequently, the more of them you need to fill up any given amount of time. A video with a frame rate of 30 fps will require twice as many frames to fill one minute as a video with a frame rate of 15 fps. Usually, the more frames you have, the bigger the size of the video file, and the more bandwidth you need to deliver that file smoothly and quickly. The size of a video file is also influenced, of course, by the physical dimensions of each of its frames. A video with dimensions of 640 px x 480 px is going to be dramatically larger than the same video, with the same compression, at half the size (320 px x 240 px).
