Video signal processing
Classification of video signal processing devices.
Today, the words “video processing” and “digital video” no longer surprise.
During the last decade, video signal processing devices have gone through a huge development path, many special terms and methods for video image processing have appeared. We will try to inform you about some video signal processing devices and methods. All video signal processing devices (VOD) can be divided into several categories:
Specialized devices that perform a limited set of functions and operate, as a rule, in real time. This category includes all kinds of video mixers, video switchers, special effects generators, synchronizers, transcoders, etc.
Video signal processing devices based on PC, Macintosh, Silicon Graphics, Amiga, Alpha DEC, etc. These devices are generally manufactured in the form of external cards or blocks that actively interact with the computer through software. These devices rarely work in real time, but they have almost limitless possibilities.
Control and auxiliary devices that control video equipment (VCRs, camcorders, video mixers, switches, etc.). They can be both standalone and part of a computer video complex. This category includes video editing controllers, online video editing boards, control systems, etc.
It should be noted that most of the above devices use digital signal processing, which has a number of advantages or is the only one possible. Digital technology is quite specific, the behavior of intelligent machines sometimes contradicts everyday human experience and is difficult to perceive. Special education, which reveals the ins and outs of digital processes, eliminates such difficulties.
However, it must be taken into account the fact that the vast majority of workers in broadcasting organizations and companies, and even more so the representatives of private and domestic video studios, are not familiar with the mathematical logic, the theory and the physics of digital processes for multidimensional processing. data matrices and other wisdom from the corresponding scientific disciplines and, most likely, will never be brought together. All they need is a tailored presentation of the basics and behavior of digital systems. We do not have specialized literature of this type, but the need is enormous. We will try in this material to provide these basic concepts, which are necessary for the correct selection of special video signal processing devices, which in the end is reflected in the efficiency of the work, obtaining optimal results and saving money.
2. What is video editing.
Before streaming any footage, it should be edited into a clean video or video movie, that is, removing “unnecessary” video clips, stitching separate pieces of video material together, transitioning between them, adding special effects and titles. That is what the devices we will talk about are designed for. There are three types of video editing: linear, non-linear, and hybrid.
Linear
means rewriting video material from two (or more) video sources to a video receiver (video recorder) with the accompaniment unnecessarily cropping and “pasting” the necessary video scenes and adding the aforementioned effects. The downside is the loss of quality (the only exception, perhaps, are professional video signal presentation formats, for example Betacam SP), high work intensity and a large number of video equipment.
Non linear
carried out on the basis of specialized computer systems. In this case, the raw video materials are first entered “into the computer”, and then the editing procedures are performed. Advantages: virtually no loss of quality during multiple video “moves”, significant savings on video equipment. Disadvantages: non-real-time work, long processing time for video material, high labor intensity (try to value half an hour of video material, which is necessary, for example, when creating educational films), limited amount of video material entered into a computer.
Hybrid
the view combines the advantages of the first two (a non-linear video editing system acts as the video source). The downside is usually the higher price.
Now let’s talk about how the video signal is organized, in what form the video image is transmitted between various video signal processing devices.
