Compression standard MPEG -4
The video data compression scheme in the MPEG-4 standard is the same as in previous MPEG formats.
During encoding, keyframes with a scene change are identified and saved, and information about changes in the current frame relative to the previous one is predicted with preservation. Also, the codec can work not only with squares, into which the image is divided, but also with objects of arbitrary shape. Of course, in this case, more important computing resources are required, but this is a characteristic of the format, which allows working with moving images (rectangular frames), arbitrarily shaped video objects, 2 D – and 3 D – synthesized objects. by a computer, animation objects and with objects from a still image.
The MPEG-4 format supports standards:
Digital television broadcasting, video information storage;
transmission of video streaming via the Internet and mobile communications;
standards for high-quality video products manufactured and distributed for studio use;
presentation of computer graphics in 2D and 3D geometry;
animation technology standards; and t. d.
It should not be thought that behind the external diversity and wide coverage of possibilities, MPEG-4 is a kind of special compression standard, since at its core it has a simple video encoding mechanism using block-based encoding with offset. movement. Furthermore, with subsequent DCT transformation, quantization and entropy coding. The basic encoding syntax, with some restrictions, is identical to that of the H. 263 standard. Most of the rest of the functionality comes from adding some details that are developed separately.
The audio part of MPEG-4 is also object-oriented. Here we use the description of the sound field in the BIFS language, which allows to place objects-sound sources in the three-dimensional space of the scene in the desired position, change the characteristics of the sound and add effects independently to each source, moving it together with the visual object.
When encoding audio objects in MPEG-4 technology, two languages SAOL (Structured Audio Orchestra Language) and SASL (Structured Audio Score Language) are incorporated, with which any instrument and any program can be programmed to reproduce synthesized sound.
The peculiarity of MPEG-4 is that the final assembly of the overall picture takes place on a computer or other receiving device and the user can form the resulting picture himself, like a television director. User commands can be processed in the decoder or sent to the source, performing the function of interactivity.
Transition of digital broadcasting in the country from MPEG-2 to MPEG-4
Regarding the transition of digital broadcasting in the country from the MPEG-2 compression standard to the MPEG-4 standard, this process was manifested in 2015, when the satellite broadcasting operators Tricolor TV, Orion and NTV plus of 2016 years after preliminary preparation, we gradually began to replace both the transmitting and user equipment.
This process was also facilitated by the order of the Ministry of Telecommunications and Mass Communications “On the approval of the Requirements for the quality of sound and (or) image of the compulsory public television channels and (or) radio channels” dated 01.09 .2015, which required telecommunications operators to provide transmission of digital signals of the first and second multiplexes in digital format. worse than using the MPEG-4 standard.
Note that the operator Tricolor TV in 2015 to 2 million subscribers have changed their equipment in the new st. In 2016, 75% of subscribers have already made an exchange.
Globally, the transition from MPEG-2 to MPEG-4 has accelerated the adoption of HD streaming. In 2016, there were more than a hundred of them on the broadcast network.
The situation is similar for other satellite operators. To speed up the exchange of equipment, Orion and NTV plus have even introduced new rules to sell MPEG-4 reception equipment in installments for two years and at a reduced price. Although, of course, the transition from one standard to another was made gradually with the preservation of parallel transmission in the MPEG-2 format, all new channels are currently broadcast in the MPEG-4 format.
