MPEG-2 бейне кодегі стандарты

Video encoding standard

MPEG 2 (a. k. a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, which permit storage and transmission of movies using currently available storage media and transmission bandwidth. While MPEG 2 is not as efficient as newer standards such as H.264/AVC and H.265/HEVC, backwards compatibility with existing hardware and software means it is still widely used, for example in over the air digital television broadcasting and in the DVD Video standard.

MPEG 2 is widely used as the format of digital television signals that are broadcast by terrestrial (over the air), cable, and direct broadcast satellite TV systems. It also specifies the format of movies and other programs that are distributed on DVD and similar discs. TV stations, TV receivers, DVD players, and other equipment are often designed to this standard. MPEG 2 was the second of several standards developed by the Moving Pictures Expert Group (MPEG) and is an international standard (ISO/IEC 13818, titled Information technology — Generic coding of moving pictures and associated audio information). Parts 1 and 2 of MPEG 2 were developed in a collaboration with ITU T, and they have a respective catalog number in the ITU T Recommendation Series. While MPEG 2 is the core of most digital television and DVD formats, it does not completely specify them. Regional institutions can adapt it to their needs by restricting and augmenting aspects of the standard. See Video profiles and levels.

MPEG 2 Part 1 (ISO/IEC 13818 1 and ITU T Rec. H.222.0), titled Systems, defines two distinct, but related, container formats. One is the transport stream, a data packet format designed to transmit one data packet in four ATM data packets for streaming digital video and audio over fixed or mobile transmission mediums, where the beginning and the end of the stream may not be identified, such as radio frequency, cable and linear recording mediums, examples of which include ATSC/DVB/ISDB/SBTVD broadcasting, and HDV recording on tape. The other is the program stream, an extended version of the MPEG 1 container format with less overhead than transport stream. Program stream is designed for random access storage mediums such as hard disk drives, optical discs and flash memory. Transport stream file formats include M2TS, which is used on Blu ray discs, AVCHD on re writable DVDs and HDV on compact flash cards. Program stream files include VOB on DVDs and Enhanced VOB on the short lived HD DVD. The standard MPEG 2 transport stream contains packets of 188 bytes. M2TS prepends each packet with 4 bytes containing a 2 bit copy permission indicator and 30 bit timestamp. ISO authorized the "SMPTE Registration Authority, LLC" as the registration authority for MPEG 2 format identifiers. The registration descriptor of MPEG 2 transport is provided by ISO/IEC 13818 1 in order to enable users of the standard to unambiguously carry data when its format is not necessarily a recognized international standard. This provision will permit the MPEG 2 transport standard to carry all types of data while providing for a method of unambiguous identification of the characteristics of the underlying private data.

MPEG 2 Part 2 (ISO/IEC 13818 2 and ITU T Rec. H.262), titled Video, is similar to the previous MPEG 1 Part 2 standard, but adds support for interlaced video, the format used by analog broadcast TV systems. MPEG 2 video is not optimized for low bit rates, especially less than 1 Mbit/s at standard definition resolutions. All standards compliant MPEG 2 Video decoders are fully capable of playing back MPEG 1 Video streams conforming to the constrained parameters bitstream (CPB) limits. With some enhancements, MPEG 2 Video and Systems are also used in some HDTV transmission systems, and is the standard format for over the air ATSC digital television.

MPEG 2 Part 3 (ISO/IEC 13818 3), titled Audio, enhances MPEG 1's audio by allowing the coding of audio programs with more than two channels, up to 5.1 multichannel. This method is backwards compatible with MPEG 1, allowing MPEG 1 audio decoders to decode the two main stereo components of the presentation. This extension is called MPEG Multichannel or MPEG 2 BC (backwards compatible). MPEG 2 Part 3 also defines additional bit rates and sampling rates for MPEG 1 Audio Layers I, II, and III. This extension is known as MPEG 2 LSF (low sampling frequencies), since the new sampling rates are one half multiples (16, 22.05 and 24 kHz) of the sampling rates defined in MPEG 1 (32, 44.1 and 48 kHz).

. mpg, mpeg, m2v, mp2, mp3 are some of a number of filename extensions used for MPEG 1 or MPEG 2 audio and video file formats. File extension MP3 (formally MPEG 1 Audio Layer III or MPEG 2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere.

The following organizations have held patents for MPEG 2, as listed at MPEG LA. See also List of United States MPEG 2 patents. Organization PatentsSony Corporation311Thomson Licensing198Mitsubishi Electric119Philips99GE Technology Development, Inc.75Panasonic Corporation55CIF Licensing, LLC44JVC Kenwood39Samsung Electronics38Alcatel Lucent (including Multimedia Patent Trust)33Cisco Technology, Inc.13Toshiba Corporation9Columbia University9LG Electronics8Hitachi7Orange S. A.7Fujitsu6Robert Bosch GmbH5General Instrument4British Telecommunications3Canon Inc.2KDDI Corporation2Nippon Telegraph and Telephone (NTT)2ARRIS Technology, Inc.2Sanyo Electric1Sharp Corporation1Hewlett Packard Enterprise Company1