MPEG-2 (a.k.a. H.222/H.262 as was defined by theITU) is a standard for "the genericcoding of moving pictures and associated audio information".[1] It describes a combination oflossyvideo compression andlossyaudio 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 asH.264/AVC andH.265/HEVC, backwards compatibility with existing hardware and software means it is still widely used, for example in over-the-airdigital television broadcasting and in theDVD-Video standard.
MPEG-2 is widely used as the format ofdigital television signals that are broadcast byterrestrial (over-the-air),cable, anddirect broadcast satelliteTV systems. It also specifies the format of movies and other programs that are distributed onDVD 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, titledInformation technology — Generic coding of moving pictures and associated audio information). Parts 1 and 2 of MPEG-2 were developed in a collaboration withITU-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. SeeVideo profiles and levels.
MPEG-2 Part 1 (ISO/IEC 13818-1 and ITU-T Rec. H.222.0[2][3]), titledSystems, defines two distinct, but related,container formats. One is thetransport stream, a data packet format designed to transmit one data packet in fourATM 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 asradio frequency,cable and linear recording mediums, examples of which includeATSC/DVB/ISDB/SBTVD broadcasting, andHDV recording on tape. The other is theprogram stream, an extended version of theMPEG-1 container format with less overhead thantransport stream.Program stream is designed for random access storage mediums such ashard disk drives,optical discs andflash memory.
Transport stream file formats includeM2TS, which is used onBlu-ray discs,AVCHD on re-writable DVDs andHDV oncompact flash cards.Program stream files includeVOB onDVDs andEnhanced VOB on the short livedHD DVD. The standard MPEG-2transport 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.[4]
MPEG-2 Part 2 (ISO/IEC 13818-2 and ITU-T Rec. H.262), titledVideo, is similar to the previousMPEG-1 Part 2 standard, but adds support forinterlaced video, the format used by analog broadcast TV systems. MPEG-2 video is not optimized for lowbit rates, especially less than 1 Mbit/s atstandard-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 someHDTV transmission systems, and is the standard format for over-the-airATSC digital television.[5]
MPEG-2 introduces new audio encoding methods compared to MPEG-1:[6]
MPEG-2 Part 3 (ISO/IEC 13818-3), titledAudio, enhancesMPEG-1's audio by allowing the coding of audio programs with more than twochannels, 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.[7] This extension is calledMPEG Multichannel or MPEG-2 BC (backwards-compatible).[8][9][10][11]
MPEG-2 Part 3 also defines additional bit rates and sampling rates for MPEG-1 Audio Layers I, II, and III.[12] 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).
MPEG-2 Part 7 (ISO/IEC 13818-7), titledAdvanced Audio Coding (AAC) specifies a rather different, non-backwards-compatible audio format.[10] This format is most commonly called Advanced Audio Coding (AAC), but was originally called MPEG-2 NBC (non-backwards-compatible).[8][9][13]
AAC is more efficient than the previous MPEG audio standards, and is in some ways less complicated than its predecessor,MPEG-1 Part 3 Audio Layer 3, in that it does not have the hybrid filter bank. It supports from 1 to 48 channels at sampling rates of 8 to 96 kHz, with multichannel, multilingual, and multiprogram capabilities.[6]
AAC is also defined inMPEG-4 Part 3.[citation needed]
MPEG-2 standards are published as "Parts". Each part covers a certain aspect of the whole specification.
| Part | Number | First public release date (first edition) | Latest public release date (last edition) | Latest amendment | Identical ITU-T Rec. | Title | Description |
|---|---|---|---|---|---|---|---|
| Part 1 | ISO/IEC 13818-1 | 1996 | 2025 | H.222.0 | Systems | Synchronization and multiplexing of video and audio. SeeMPEG transport stream andMPEG program stream. | |
| Part 2 | ISO/IEC 13818-2 | 1996 | 2013 | H.262 | Video | Video coding format for interlaced and non-interlaced video signals | |
| Part 3 | ISO/IEC 13818-3 | 1995 | 1998 | Audio | Audio coding format for perceptual coding of audio signals. A multichannel-enabled extension and extension of bit rates and sample rates for MPEG-1 Audio Layer I, II and III. Backwards-compatible (BC) audio (backwards-compatible with MPEG-1). | ||
| Part 4 | ISO/IEC 13818-4 | 1998 | 2004 | 2009[16] | Conformance testing | ||
| Part 5 | ISO/IEC TR 13818-5 | 1997 | 2005 | Software simulation | |||
| Part 6 | ISO/IEC 13818-6 | 1998 | 1998 | 2001[17] | Extensions for DSM-CC | DSM-CC (digital storage media command and control)[18][19] | |
| Part 7 | ISO/IEC 13818-7 | 1997 | 2006 | 2007[20] | Advanced Audio Coding (AAC) | Advanced Audio Coding (AAC). Non-backwards-compatible (NBC) audio (not backwards-compatible with MPEG-1). | |
| Part 8 | Withdrawn | 10-bit video extension. Primary application was studio video, allowing artifact-free processing without giving up compression. Work began in 1995, but was terminated in 2007 because of insufficient industry interest.[21][22] | |||||
| Part 9 | ISO/IEC 13818-9 | 1996 | 1996 | Extension for real time interface for systems decoders | |||
| Part 10 | ISO/IEC 13818-10 | 1999 | 1999 | Conformance extensions for Digital Storage Media Command and Control (DSM-CC) | |||
| Part 11 | ISO/IEC 13818-11 | 2004 | 2004 | IPMP on MPEG-2 systems | Intellectual Property Management and Protection (IPMP).[23][24] XML IPMP messages are also defined in ISO/IEC 23001-3.[25] |
MPEG-2 evolved out of the shortcomings of MPEG-1.
MPEG-1's known weaknesses:
Sakae Okubo ofNTT was theITU-T coordinator for developing theH.262/MPEG-2 Part 2 video coding standard and the requirements chairman inMPEG for the MPEG-2 set of standards.[26] The majority of patents underlying MPEG-2 technology are owned by three companies:Sony (311 patents),Thomson (198 patents) andMitsubishi Electric (119 patents).[27]Hyundai Electronics (nowSK Hynix) developed the first MPEG-2 SAVI (System/Audio/Video) decoder in 1995.[28]
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.mpg,.mpeg, and.m2v are some of a number of filename extensions used for MPEG-2 audio and video file formats..mpg and particularly.mpeg are also used for MPEG-1 formats.
File extensionMP3 (formallyMPEG-1 Audio Layer III orMPEG-2 Audio Layer III) is acoding format fordigital audio developed largely by theFraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere.
TheDVD-Video standard uses MPEG-2 video, but imposes some restrictions:
HDV is a format for recording and playback of high-definition MPEG-2 video on a DV cassette tape.
MOD and TOD are recording formats for use in consumer digital file-based camcorders.
XDCAM is a professional file-based video recording format.
Application-specific restrictions on MPEG-2 video in theDVB standard:
Allowed resolutions forSDTV:
For HDTV:
The ATSC A/53 standard used in the United States, uses MPEG-2 video at the Main Profile @ High Level (MP@HL), with additional restrictions such as the maximum bitrate of 19.39 Mbit/s for broadcast television and 38.8 Mbit/s for cable television, 4:2:0chroma subsampling format, and mandatory colorimetry information.
ATSC allows the following video resolutions, aspect ratios, and frame/field rates:
ATSC standard A/63 defines additional resolutions and aspect rates for 50 Hz (PAL) signal.
The ATSC specification and MPEG-2 allow the use of progressive frames, even within an interlaced video sequence. For example, a station that transmits 1080i60 video sequence can use a coding method where those 60 fields are coded with 24 progressive frames and metadata instructs the decoder to interlace them and perform 3:2 pulldown before display. This allows broadcasters to switch between 60 Hz interlaced (news, soap operas) and 24 Hz progressive (prime-time) content without ending the MPEG-2 sequence and introducing several seconds of delay as the TV switches formats. This is the reason why 1080p30 and 1080p24 sequences allowed by the ATSC specification are not used in practice.
The 1080-line formats are encoded with 1920 × 1088 pixel luma matrices and 960 × 540 chroma matrices, but the last 8 lines are discarded by the MPEG-2 decoding and display process.
ATSC A/72 is the newest revision of ATSC standards for digital television, which allows the use of H.264/AVC video coding format and 1080p60 signal.
MPEG-2 audio was a contender for the ATSC standard during theDTV "Grand Alliance" shootout, but lost out toDolby AC-3.
Technical features of MPEG-2 in ATSC are also valid forISDB-T, except that in the main TS has aggregated a second program for mobile devices compressed inMPEG-4 H.264 AVC for video andAAC-LC for audio, mainly known as1seg.
MPEG-2 is one of the three supported video coding formats supported by Blu-ray Disc. Early Blu-ray releases typically used MPEG-2 video, but recent releases are almost always inH.264 or occasionallyVC-1. Only MPEG-2 video (MPEG-2 part 2) is supported, Blu-ray does not support MPEG-2 audio (parts 3 and 7). Additionally, the container format used on Blu-ray discs is an MPEG-2 transport stream, regardless of which audio and video codecs are used.
As of January 3, 2024, MPEG-2patents haveexpired worldwide, with the exception of only Malaysia, where the last patent is expected to expire in 2035.[29] The last US patent expired on February 23, 2018.[30][31]
MPEG LA, a private patent licensing organization, had acquired rights from over 20 corporations and one university to license apatent pool of approximately 640 worldwide patents, which it claimed were "essential" to use of MPEG-2 technology. The patent holders includedSony,Mitsubishi Electric,Fujitsu,Panasonic,Scientific Atlanta,Columbia University,Philips,General Instrument,Canon,Hitachi,JVC Kenwood,LG Electronics,NTT,Samsung,Sanyo,Sharp andToshiba.[32][33] WhereSoftware patentability is upheld and patents have not expired (only Malaysia), the use of MPEG-2 requires the payment of licensing fees to the patent holders. Other patents were licensed by Audio MPEG, Inc.[34] The development of the standard itself took less time than the patent negotiations.[35] Patent pooling between essential and peripheral patent holders in the MPEG-2 pool was the subject of a study by the University of Wisconsin.[36]
According to the MPEG-2 licensing agreementany use of MPEG-2 technology in countries with active patents (Malaysia) is subject toroyalties.[37] MPEG-2 encoders and decoders are subject to $0.35 per unit.[37] Also, any packaged medium (DVDs/Data Streams) is subject to licence fees according to length of recording/broadcast. The royalties were previously priced higher but were lowered at several points, most recently on January 1, 2018.[37] An earlier criticism of the MPEG-2 patent pool was that even though the number of patents had decreased from 1,048 to 416 by June 2013 the license fee had not decreased with the expiration rate of MPEG-2 patents.[38][39][40]
The following organizations have held patents for MPEG-2, as listed atMPEG LA. See alsoList of United States MPEG-2 patents.
| Organization | Patents[27] |
|---|---|
| Sony Corporation | 311 |
| Thomson Licensing | 198 |
| Mitsubishi Electric | 119 |
| Philips | 99 |
| GE Technology Development, Inc. | 75 |
| Panasonic Corporation | 55 |
| CIF Licensing, LLC | 44 |
| JVC Kenwood | 39 |
| Samsung Electronics | 38 |
| Alcatel Lucent (including Multimedia Patent Trust) | 33 |
| Cisco Technology, Inc. | 13 |
| Toshiba Corporation | 9 |
| Columbia University | 9 |
| LG Electronics | 8 |
| Hitachi | 7 |
| Orange S.A. | 7 |
| Fujitsu | 6 |
| Robert Bosch GmbH | 5 |
| General Instrument | 4 |
| British Telecommunications | 3 |
| Canon Inc. | 2 |
| KDDI Corporation | 2 |
| Nippon Telegraph and Telephone (NTT) | 2 |
| ARRIS Technology, Inc. | 2 |
| Sanyo Electric | 1 |
| Sharp Corporation | 1 |
| Hewlett-Packard Enterprise Company | 1 |
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