The composite video signal format defined by the NTSC (National Television Standards Committee) color television system is used in the United States. Therefore, a standard composite video signal is usually separated into its basic components before it is digitized. This type of signal is called a composite video signal and is not really useful in high- quality computer video. The value of the threshold closest to the amplitude of the sampled signal is used as the digital value.Ī video signal contains several different components which are mixed together in the same signal. The value is selected by comparing the video sample to a series of predefined threshold values. This value approximates the level of the original video signal sample. Quantizing converts the level of a video signal sample into a discrete, binary value. For digital video, it is necessary to capture millions of samples per second. The sampling rate is measured in the number of samples captured per second (samples/second). The rate at which samples are collected is called the sampling rate. Quantizing converts each captured sample into a digital format.Įach sample captured from the video stream is typically stored as a 16-bit integer. Sampling captures data from the video stream.The process of converting a video signal to a digital bitstream is called analog-to-digital conversion (A/D conversion), or digitizing. In a digital format, the video data can be stored as a series of bits on a hard disk or in computer memory. In order for a computer to process this video data, we must convert the analog signals to a non-continuous, digital format. Video data normally occurs as continuous, analog signals. Only in the last few years has a personal computer been able to work with video data at all. There are many complex signals and complicated standards that are involved in transmitting those late-night reruns across the airwaves and cable. Your television and video tape recorder are a lot more complex than an 8mm home movie projector and your kitchen wall. One step beyond animation is broadcast video. Movie special effects benefit greatly by computer animation. Animated sequences are used by CAD programmers to rotate 3D objects so they can be observed from different perspectives mathematical data collected by an aircraft or satellite may be rendered into an animated fly-by sequence. Most animation formats cannot store sound directly in their files and must rely on storing the sound in a separate disk file which is read by the application that is playing back the animation.Īnimations are not only for entertaining kids and adults. Storing animations using a multimedia format also produces the benefit of adding sound to the animation (what’s a cartoon without sound?). RLE is relatively easy to decompress on the fly. Most animation files use a delta compression scheme, which is a form of Run-Length Encoding that stores and compresses only the information that is different between two images (rather than compressing each image frame entirely). The image-compression schemes used in animation files are also usually much simpler than most of those used in video compression. It is possible, however, for most multimedia formats to contain animation information, because animation is actually a much easier type of data than video to store. An animation file, however, must store the data for hundreds or thousands of animation frames and must also provide the information necessary to play back the frames using the proper display mode and frame rate.Īnimation file formats are only capable of storing still images and not actual video information. Each frame, or cell, of an animation is a still image that requires compression and storage. When these images are displayed (played back) in the proper sequence and at the proper speed (frame rate), the subject appears to move.Ĭomputerized animation is actually a combination of both still and motion imaging. When a large number of these cells is displayed in sequence and at a fast rate, the animated figures appear to the human eye to move.Ī computer-animated sequence works in exactly the same manner, i.e a series of images is created of a subject each image contains a slightly different perspective on the animated subject. Traditional cartoon animation is little more than a series of artwork cells, each containing a slight positional variation of the animated subjects. All of the animated sequences seen in educational programs, motion CAD renderings, and computer games are computer-animated (and in many cases, computer-generated) animation sequences. \)Ĭomputer animation lies somewhere between the motionless world of still images and the real-time world of video images.
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