Description of the MPEG-2 and MPEG-4 compression formats
A distinctive feature of video data is its extremely large volume.
Data compression specialists have been working for many years to improve the efficiency of video compression algorithms. At the beginning of the 21st century, with the advent of HDTV, there was an urgent need to transmit large amounts of video information over satellite and cable networks, and the task of optimizing video data encoding methods arose.
Today, MPEG-2 is a digital encoding standard for audio and video signals that is used by most satellite television operators to transmit signals to subscribers. This standard was developed by Moving Pictures Experts Group and has been approved by the International Organization for Standardization.
Technical aspects of the MPEG-2 standard
The MPEG working group described the general principles of audio and video compression and left the details to the codec manufacturers. The compression algorithm was based on the human eye perception model of video images and the structural characteristics of the human eye: its ability to perceive color variations and brightness gradations. For example, the human eye can better perceive gradations of brightness than chromaticity.
The task is reduced to determining a stationary background and moving objects on the screen, on the basis of this, it is possible to select and transmit information about the base frame, and then transmit frames with information about moving objects. Insignificant information is discarded in the data transmission process, similar to the principles used in the JPEG graphic format. The process is done by dividing the video information stream into groups of video images, each group consists of 3 types of video frames. Sequences of 30 frames per second are typically used.
Due to the constant improvement of MPEG-2 video codecs, cable and satellite transmission operators have been able to transmit twice as much information with the same channel bandwidth as at the dawn of the evolution of digital transmission. An increasing number of different video codecs began to appear, but they no longer corresponded to the existing MPEG-2 format. A further unification of the norm is necessary.
