By definition, video decoding is the opposite of encoding. It consists in the decompression and decoding of video and audio files that are already encoded. A good example can be found when opening a stream on Twitch or a video on YouTube.
The video decoder is the software or hardware in charge of the process. It converts the encoded video signals into digital files so that they can be played on any device, performing the opposite function of a video encoder.
To allow playback of certain audio files and encoded videos, we will need a particular video decoding software, or a plugin such as FFDShow.
Video decoding incorporates several important processes. First, an analog-to-digital converter digitizes the signal and outputs a data stream, which can be modified to adjust brightness, saturation and contrast. It is then transformed by a color space converter so that it can be properly displayed on the screen.