Recording and playing back video on a computer is a trade-off between frame rate, movie size, colour depth, and storage size. Frame Rate The frame rate is the number of frames per second (fps) that can be shown on the monitor. The greater the frame rate the more fluid the video will appear. Unfortunately increasing the frame rate also increases the amount of data that needs to be transferred from the hard disc and displayed on the monitor. This slows up the video. If you are recording your own videos, don’t use a frame rate less than 15 fps or it will appear very jerky. Movie Size The movie size is measured in pixels. Early movie sizes on computers were about 160 x 120 pixels (about the size of two postage stamps), these days a common movie size is 640 x 480 pixels - about one quarter of the monitor area. Most viewers would rather watch a small smooth, good quality video, rather than a large poor quality video. Very few computers today can cope with larger than 320x240 pixels. Colour Depth As you will have already seen, to the human eye there is practically no quality difference between millions of colours (24-bit) and thousands of colours (16-bit), so is not worth the extra storage and processing required. As long as it does not degrade the quality of the video too much, you can sometimes get away with 256 colours (8-bit). Storage Space Even if you are distributing your video on CD-R, it still only holds 650 megabytes of information. Video must be compressed, preferably using MPEG compression, so that you can store enough video and transfer it fast enough for the video board to display it. Search the internet for the following video clips or similar, noting the file name, size and type in your jotter:
Answer the following questions in your jotter, displaying all working.
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