What is Video in Multimedia

Video Video, like sound, is recorded and played an as analog signal Analog video must be digitized in order for it to put into a multimedia file Digital video has many advantages, but file size is important

Video Several elements determine file size: – Frame rate – Image size – Color depth To determine file size use the following formula: – Frames per second X image size X color depth / 8 = file size

Video Compression and Editing There are two types of video compression – Lossless – preserves the exact image throughout the compression – Lossy – eliminates some of the data in the image (provides greater compression ratios than lossless) – Remember – there is always a trade off, file size versus image quality

Video on the Internet There are two types of video transfer over the Internet – HTTP (Hypertext Transfer Protocol) – downloads the entire video to the hard drive on the user’s computer – RTSP (Real-Time Streaming Protocol) – is a continuous-playing, streaming technology in which the user’s computer is in constant contact with the server playing the video

Video Tips Color depth Reducing the color depth to less than 256 colors gives a markedly poorer-quality image. Frame rate Reducing the frame rate to less than 15 frames per second causes a noticeable and distracting jerkiness that is usually unacceptable. File sizeA technique for reducing file size is to minimize the use of video in the image that appears on the screen – that is, to create video only for the parts of an object that are changing, such as a flickering candle. The video could be played over and over to create the motion of a flickering candle.

Video Tips Display sizeIn most multimedia titles, you do not need to show full-screen video. The video can be played in a window that can be as small as one-fourth or even one-sixteenth the size of the screen. Conclusion: Changing the image size and compressing the file become the primary ways of reducing file size. In most cases, a one-quarter screen image (320 X 240), an 8- bit (256 colors) color depth, and a 15 frames per second frame rate are acceptable in a multimedia title.