MPEG-4 Part 2,MPEG-4 Visual (formallyISO/IEC 14496-2[1]) is a video encoding specification designed by theMoving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC family of encoders. It uses block-wisemotion compensation and adiscrete cosine transform (DCT), similar to previous encoders such asMPEG-1 Part 2 andH.262/MPEG-2 Part 2.
Examples of popular implementations of the encoder specifications includeDivX,Xvid andNero Digital.
MPEG-4 Part 2 isH.263 compatible in the sense that a basic H.263 bitstream is correctly decoded by an MPEG-4 Video decoder. (MPEG-4 Video decoder is natively capable of decoding a basic form of H.263.)[2][3][4] In MPEG-4 Visual, there are two types of video object layers: the video object layer that provides full MPEG-4 functionality, and a reduced functionality video object layer, the video object layer with short headers (which provides bitstream compatibility with base-line H.263).[5] MPEG-4 Part 2 is partially based on ITU-T H.263.[6] The first MPEG-4 Video Verification Model (simulation and test model) used ITU-T H.263 coding tools together with shape coding.[7]
The MPEG-4 Visual format was developed by theMoving Picture Experts Group (MPEG) committee. The specification was authored byIranian-Swiss engineer Touradj Ebrahimi (later the president ofJPEG) andDutch engineer Caspar Horne.[5] The standard was developed using patents from over a dozen organizations, listed byMPEG LA in apatent pool. The majority of patents used for the MPEG-4 Visual format were from threeJapanese companies:Mitsubishi Electric (255 patents),Hitachi (206 patents), andPanasonic (200 patents).[8] SeePatent holders below for a full list of patent holders.
| Edition | Release date | Latest amendment | Standard | Description |
|---|---|---|---|---|
| First edition | 1999 | 2000 | ISO/IEC 14496-2:1999[10] | |
| Second edition | 2001 | 2003 | ISO/IEC 14496-2:2001[11] | |
| Third edition | 2004 | 2009[1] | ISO/IEC 14496-2:2004[1] |
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To address various applications ranging from low-quality, low-resolution surveillance cameras to high definition TV broadcasting and DVDs, many video standards group features into profiles and levels. MPEG-4 Part 2 contains approximately 21 profiles.
The most commonly deployed profiles are theAdvanced Simple Profile (ASP or AS Profile) and theSimple Profile (SP), which is a subset of the ASP.
Other profiles include the Advanced Coding Efficiency Profile (ACEP or ACE Profile), the Advanced Real Time Simple Profile (ARTSP or ARTS Profile), the Core Profile (CP), the Main Profile (MP), and theSimple Studio Profile (SStP or SSt Profile).
Most of the video compression schemes standardize thebitstream (and thus the decoder) leaving theencoder design to the individual implementations. Therefore, implementations for a particular profile (such as DivX or Nero Digital which are implementations of Advanced Simple Profile and Xvid that implements both profiles) are all technically identical on the decoder side. A point of comparison would be that an MP3 file can be played in any MP3 player, whether it was created through iTunes, Windows Media Player,LAME, or the common Fraunhofer encoder.
TheSimple Profile is mostly aimed for use in situations where low bit rate and low resolution are mandated by other conditions of the applications, like network bandwidth, device size etc. Examples aremobile phones, some low endvideo conferencing systems,electronic surveillance systems etc.
| Level | Max. buffer | Max. bitrate | Max. delay at max. bitrate | Max. VP size | Max. VOP size | Max. decoder rate | Max. framesize | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| @ 30 Hz | @ 25 Hz | @ 24 Hz | @ 15 Hz | @ 12.5 Hz | |||||||
| 0 | 160 | 64 | 2.50 | 2,048 | 99 | 1,485 | — | QCIF (176×144) | |||
| 0b | 320 | 128 | |||||||||
| 1 | 160 | 64 | 128×96 | 144×96 | 160×96 | ||||||
| 2 | 640 | 128 | 5.00 | 4,096 | 396 | 5,940 | 256×192 | 304×192, 288×208 | 304×208 | CIF (352×288) | |
| 3 | 384 | 1.66 | 8,192 | 11,880 | CIF (352×288) | ||||||
| 4a | 1,280 | 4,000 | 0.32 | 16,384 | 1,200 | 36,000 | VGA (640×480) | ||||
| 5 | 1,792 | 8,000 | 0.22 | 1,620 | 40,500 | D1 NTSC (720×480) | D1 PAL (720×576) | ||||
| 6 | 3,968 | 12,000 | 0.33 | 3,600 | 108,000 | 720p (1280x720) | |||||
| Units | kbits | kbits/s | seconds | bits | macroblocks | macroblocks/s | pixels | ||||
TheAdvanced Simple Profile was not included in the original standard. Its notable technical features relative to the Simple Profile, which is roughly similar toH.263, include:
The MPEG quantization and interlace support are designed in basically similar ways to the way it is found inMPEG-2 Part 2. The B picture support is designed in a basically similar way to the way it is found in MPEG-2 Part 2 andH.263v2.
The quarter-pixel motion compensation feature of ASP was innovative, and was later also included (in somewhat different forms) in later designs such asMPEG-4 Part 10,HEVC,VC-1 andVVC. Some implementations of MPEG-4 Part 2 omit support for this feature, because it has a significantly harmful effect on the speed of software decoders and it is not always beneficial for quality.
The global motion compensation feature is not actually supported in most implementations although the standard officially requires decoders to support it. Most encoders do not support it either, and some experts say that it does not ordinarily provide any benefit in compression. When used, ASP's global motion compensation has a large unfavorable impact on speed and adds considerable complexity to the implementation.
| Level | Max. buffer | Max. bitrate | Max. delay at max. bitrate | Max. VP size | Max. VOP size | Max. decoder rate | Max. framesize | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| @ 30 Hz | @ 25 Hz | @ 24 Hz | @ 15 Hz | @ 12.5 Hz | |||||||
| 0 | 160 | 128 | 1.25 | 2,048 | 99 | 2,970 | QCIF (176×144) | ||||
| 1 | |||||||||||
| 2 | 640 | 384 | 1.66 | 4,096 | 396 | 5,940 | 256×192 | 304×192, 288×208 | 304×208 | CIF (352×288) | |
| 3 | 768 | 0.86 | 11,880 | CIF (352×288) | |||||||
| 3b | 1,040 | 1,500 | 0.69 | ||||||||
| 4 | 1,280 | 3,000 | 0.43 | 8,192 | 792 | 23,760 | 352×576, 704×288 | ||||
| 5 | 1,792 | 8,000 | 0.22 | 16,384 | 1,620 | 48,600 | 720×576 | ||||
| Units | kbits | kbits/s | seconds | bits | macroblocks | macroblocks/s | pixels | ||||
TheSimple Studio Profile has six levels, ranging fromSDTV to4K resolution.[12] SStP allows for up to 12-bitbit depth and up to 4:4:4chroma subsampling,[12] using intra-frame coding only.[13] SStP is used byHDCAM SR.[12]
| Level | Max. bit depth and chroma subsampling | Max. resolution and frame rate | Max. data rate (Mbit/s) |
|---|---|---|---|
| 1 | 10-bit 4:2:2 | SDTV | 180 |
| 2 | 10-bit 4:2:2 | 1920×1080 30p/30i | 600 |
| 3 | 12-bit 4:4:4 | 1920×1080 30p/30i | 900 |
| 4 | 12-bit 4:4:4 | 2K×2K 30p | 1,350 |
| 5 | 12-bit 4:4:4 | 4K×2K 30p | 1,800 |
| 6 | 12-bit 4:4:4 | 4K×2K 60p | 3,600 |
MPEG-4 Part 2patents haveexpired worldwide, the last one on January 28, 2024.[14] The following organizations held patents for MPEG-4 Visual technology, as listed in thepatent pool administered byMPEG LA.
| Organization[15] | Patents[8] |
|---|---|
| Mitsubishi Electric | 255 |
| Hitachi | 206 |
| Panasonic | 200 |
| Sun Patent Trust | 125 |
| Toshiba | 96 |
| Samsung Electronics | 92 |
| Sony | 84 |
| Philips | 73 |
| Sharp Corporation | 44 |
| Pantech | 36 |
| Robert Bosch GmbH | 27 |
| Nippon Telegraph and Telephone | 24 |
| GE Technology Development | 23 |
| CIF Licensing | 20 |
| Dolby | 19 |
| Telenor | 19 |
| Siemens AG | 15 |
| JVC Kenwood | 14 |
| Orange S.A. | 14 |
| LG Electronics | 13 |
| Fujitsu | 11 |
| ZTE | 10 |
| 9 | |
| BT Group | 3 |
| Calmare Therapeutics | 2 |
| Cable Television Laboratories, Inc. | 1 |
| Canon Inc. | 1 |
| KDDI | 1 |
| Microsoft | 1 |
| Oki Electric Industry | 1 |
| Sanyo | 1 |
MPEG-4 Part 2 has drawn some industry criticism.FFmpeg's maintainer Michael Niedermayer has criticised MPEG-4 for lacking an in-loopdeblocking filter, GMC being too computationally intensive, andOBMC being defined but not allowed in any profiles among other things.[16]Microsoft's Ben Waggoner states "Microsoft (well before my time) went down the codec standard route before with MPEG-4 part 2, which turns out to be a profound disappointment across the industry - it didn't offer that much of a compression advantage over MPEG-2, and the protracted license agreement discussions scared off a lot of adoption. I was involved in many digital media projects that wouldn't even touch MPEG-4 in the late 1990s to early 2000s because there was going to be a 'content fee' that hadn't been fully defined yet."[17]
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