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63-519: MPEG formats are used in various multimedia systems. The most well known older MPEG media formats typically use MPEG-1 , MPEG-2 , and MPEG-4 AVC media coding and MPEG-2 systems transport streams and program streams . Newer systems typically use the MPEG base media file format and dynamic streaming (a.k.a. MPEG-DASH ). MPEG was established in 1988 by the initiative of Dr. Hiroshi Yasuda ( NTT ) and Dr. Leonardo Chiariglione ( CSELT ). Chiariglione

126-414: A B-frame. Because of this, a very low bitrate B-frame can be inserted, where needed, to help control the bitrate. If this was done with a P-frame, future P-frames would be predicted from it and would lower the quality of the entire sequence. However, similarly, the future P-frame must still encode all the changes between it and the previous I- or P- anchor frame. B-frames can also be beneficial in videos where

189-506: A GOP size of 15–18. i.e. 1 I-frame for every 14-17 non-I-frames (some combination of P- and B- frames). With more intelligent encoders, GOP size is dynamically chosen, up to some pre-selected maximum limit. Limits are placed on the maximum number of frames between I-frames due to decoding complexing, decoder buffer size, recovery time after data errors, seeking ability, and accumulation of IDCT errors in low-precision implementations most common in hardware decoders (See: IEEE -1180). "P-frame"

252-462: A bitrate less than 1.5 Mbit/s, make up what is known as a constrained parameters bitstream (CPB), later renamed the "Low Level" (LL) profile in MPEG-2. This is the minimum video specifications any decoder should be able to handle, to be considered MPEG-1 compliant . This was selected to provide a good balance between quality and performance, allowing the use of reasonably inexpensive hardware of

315-599: A joint project between MPEG and ITU-T Study Group 15 (which later became ITU-T SG16), resulting in publication of the MPEG-2 Systems standard (ISO/IEC 13818-1, including its transport streams and program streams ) as ITU-T H.222.0 and the MPEG-2 Video standard (ISO/IEC 13818-2) as ITU-T H.262. Sakae Okubo (NTT), was the ITU-T coordinator and chaired the agreements on its requirements. Joint Video Team (JVT)

378-601: A largely complete draft standard was produced in September 1990, and from that point on, only minor changes were introduced. The draft standard was publicly available for purchase. The standard was finished with the 6 November 1992 meeting. The Berkeley Plateau Multimedia Research Group developed an MPEG-1 decoder in November 1992. In July 1990, before the first draft of the MPEG-1 standard had even been written, work began on

441-410: A picture) redundancy common in video to achieve better data compression than would be possible otherwise. (See: Video compression ) Before encoding video to MPEG-1, the color-space is transformed to Y′CbCr (Y′=Luma, Cb=Chroma Blue, Cr=Chroma Red). Luma (brightness, resolution) is stored separately from chroma (color, hue, phase) and even further separated into red and blue components. The chroma

504-408: A portion of an MPEG program, and is also used by the decoder to determine when data can be discarded from the buffer . Either video or audio will be delayed by the decoder until the corresponding segment of the other arrives and can be decoded. PTS handling can be problematic. Decoders must accept multiple program streams that have been concatenated (joined sequentially). This causes PTS values in

567-412: A profile of the standard. Two implementations engineered from the same description may not interoperate due to having a different profile of the standard. Vendors can even ignore features that they view as unimportant, yet prevail in the long run. The use of profiles in these ways can force one interpretation, or create de facto standards from official standards. Engineers can design or procure by using

630-773: A profile to ensure interoperability. For example, the International Standard Profile, ISP, is used by the ISO in their ISO ISP series of standards; in the context of OSI networking , Britain uses the UK-GOSIP profile and the US uses US- GOSIP ; there are also various mobile profiles adopted by the W3C for web standards. In particular, implementations of standards on mobile devices often have significant limitations compared to their traditional desktop implementations, even if

693-431: A second standard, MPEG-2 , intended to extend MPEG-1 technology to provide full broadcast-quality video (as per CCIR 601 ) at high bitrates (3–15  Mbit/s) and support for interlaced video. Due in part to the similarity between the two codecs, the MPEG-2 standard includes full backwards compatibility with MPEG-1 video, so any MPEG-2 decoder can play MPEG-1 videos. Notably, the MPEG-1 standard very strictly defines

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756-480: A single stream, ensuring simultaneous delivery, and maintaining synchronization. The PS structure is known as a multiplex , or a container format . Presentation time stamps (PTS) exist in PS to correct the inevitable disparity between audio and video SCR values (time-base correction). 90 kHz PTS values in the PS header tell the decoder which video SCR values match which audio SCR values. PTS determines when to display

819-691: A source of annoyance. Because of the subsampling, Y′CbCr 4:2:0 video is ordinarily stored using even dimensions ( divisible by 2 horizontally and vertically). Y′CbCr color is often informally called YUV to simplify the notation, although that term more properly applies to a somewhat different color format. Similarly, the terms luminance and chrominance are often used instead of the (more accurate) terms luma and chroma. MPEG-1 supports resolutions up to 4095×4095 (12 bits), and bit rates up to 100 Mbit/s. MPEG-1 videos are most commonly seen using Source Input Format (SIF) resolution: 352×240, 352×288, or 320×240. These relatively low resolutions, combined with

882-457: A specific video is. I-frame only MPEG-1 video is very similar to MJPEG video. So much so that very high-speed and theoretically lossless (in reality, there are rounding errors) conversion can be made from one format to the other, provided a couple of restrictions (color space and quantization matrix) are followed in the creation of the bitstream. The length between I-frames is known as the group of pictures (GOP) size. MPEG-1 most commonly uses

945-473: A video at high speed. Given moderately higher-performance decoding equipment, fast preview can be accomplished by decoding I-frames instead of D-frames. This provides higher quality previews, since I-frames contain AC coefficients as well as DC coefficients. If the encoder can assume that rapid I-frame decoding capability is available in decoders, it can save bits by not sending D-frames (thus improving compression of

1008-407: A video coding standard that further reduces by about 50% the data rate required for video coding, as compared to the then-current ITU-T H.264 / ISO/IEC 14496-10 standard. JCT-VC was co-chaired by Prof. Jens-Rainer Ohm and Gary Sullivan. Joint Video Experts Team (JVET) is a joint group of video coding experts from ITU-T Study Group 16 (VCEG) and ISO/IEC JTC 1/SC 29/WG 11 (MPEG) created in 2017, which

1071-453: Is also subsampled to 4:2:0 , meaning it is reduced to half resolution vertically and half resolution horizontally, i.e., to just one quarter the number of samples used for the luma component of the video. This use of higher resolution for some color components is similar in concept to the Bayer pattern filter that is commonly used for the image capturing sensor in digital color cameras. Because

1134-402: Is an abbreviation for "Predicted-frame". They may also be called forward-predicted frames or inter-frames (B-frames are also inter-frames). P-frames exist to improve compression by exploiting the temporal (over time) redundancy in a video. P-frames store only the difference in image from the frame (either an I-frame or P-frame) immediately preceding it (this reference frame is also called

1197-532: Is approved at the Subcommittee level and then at the Technical Committee level (SC 29 and JTC 1, respectively, in the case of MPEG). When the scope of new work is sufficiently clarified, MPEG usually makes open "calls for proposals". The first document that is produced for audio and video coding standards is typically called a test model. When a sufficient confidence in the stability of

1260-571: Is defined by the standard, and small errors in the bitstream may cause noticeable defects. This structure was later named an MPEG program stream : "The MPEG-1 Systems design is essentially identical to the MPEG-2 Program Stream structure." This terminology is more popular, precise (differentiates it from an MPEG transport stream ) and will be used here. Program Streams (PS) are concerned with combining multiple packetized elementary streams (usually just one audio and video PES) into

1323-472: Is defined in ISO/IEC-11172-2. The design was heavily influenced by H.261 . MPEG-1 Video exploits perceptual compression methods to significantly reduce the data rate required by a video stream. It reduces or completely discards information in certain frequencies and areas of the picture that the human eye has limited ability to fully perceive. It also exploits temporal (over time) and spatial (across

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1386-442: Is designed to compress VHS -quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making video CDs , digital cable / satellite TV and digital audio broadcasting (DAB) practical. Today, MPEG-1 has become the most widely compatible lossy audio/video format in the world, and is used in a large number of products and technologies. Perhaps

1449-487: Is no longer covered by any essential patents and can thus be used without obtaining a licence or paying any fees. The ISO patent database lists one patent for ISO 11172, US 4,472,747, which expired in 2003. The near-complete draft of the MPEG-1 standard was publicly available as ISO CD 11172 by December 6, 1991. Neither the July 2008 Kuro5hin article "Patent Status of MPEG-1, H.261 and MPEG-2", nor an August 2008 thread on

1512-524: Is one Cb block of 8x8 and one Cr block of 8x8. This set of 6 blocks, with a picture resolution of 16×16, is processed together and called a macroblock . All of these 8x8 blocks are independently put through DCT and quantization. A macroblock is the smallest independent unit of (color) video. Motion vectors (see below) operate solely at the macroblock level. If the height or width of the video are not exact multiples of 16, full rows and full columns of macroblocks must still be encoded and decoded to fill out

1575-484: Is only possible to the nearest I-frame. When cutting a video it is not possible to start playback of a segment of video before the first I-frame in the segment (at least not without computationally intensive re-encoding). For this reason, I-frame-only MPEG videos are used in editing applications. I-frame only compression is very fast, but produces very large file sizes: a factor of 3× (or more) larger than normally encoded MPEG-1 video, depending on how temporally complex

1638-414: Is sent for another ballot. After a review and comments issued by NBs and a resolution of comments in the working group, a Final Draft International Standard (FDIS) is typically issued for a final approval ballot. The final approval ballot is voted on by National Bodies, with no technical changes allowed (a yes/no approval ballot). If approved, the document becomes an International Standard (IS). In cases where

1701-489: The anchor frame ). The difference between a P-frame and its anchor frame is calculated using motion vectors on each macroblock of the frame (see below). Such motion vector data will be embedded in the P-frame for use by the decoder. A P-frame can contain any number of intra-coded blocks (DCT and Quantized), in addition to any forward-predicted blocks (Motion Vectors). If a video drastically changes from one frame to

1764-618: The MP3 article. All patents in the world connected to MP3 expired 30 December 2017, which makes this format totally free for use. On 23 April 2017, Fraunhofer IIS stopped charging for Technicolor's MP3 licensing program for certain MP3 related patents and software. The following corporations filed declarations with ISO saying they held patents for the MPEG-1 Video (ISO/IEC-11172-2) format, although all such patents have since expired. Part 1 of

1827-592: The Moving Picture Experts Group (MPEG) working group was established in January 1988, by the initiative of Hiroshi Yasuda ( Nippon Telegraph and Telephone ) and Leonardo Chiariglione ( CSELT ). MPEG was formed to address the need for standard video and audio formats, and to build on H.261 to get better quality through the use of somewhat more complex encoding methods (e.g., supporting higher precision for motion vectors). Development of

1890-598: The bitstream , and decoder function, but does not define how MPEG-1 encoding is to be performed, although a reference implementation is provided in ISO/IEC-11172-5. This means that MPEG-1 coding efficiency can drastically vary depending on the encoder used, and generally means that newer encoders perform significantly better than their predecessors. The first three parts (Systems, Video and Audio) of ISO/IEC 11172 were published in August 1993. Due to its age, MPEG-1

1953-554: The MPEG section of Chiariglione's personal website was updated to inform readers that he had retired as Convenor, and he said that the MPEG group (then SC 29/WG 11) "was closed". Chiariglione described his reasons for stepping down in his personal blog. His decision followed a restructuring process within SC 29 , in which "some of the subgroups of WG 11 (MPEG) [became] distinct MPEG working groups (WGs) and advisory groups (AGs)" in July 2020. Prof. Jörn Ostermann of University of Hannover

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2016-534: The MPEG-1 standard began in May 1988. Fourteen video and fourteen audio codec proposals were submitted by individual companies and institutions for evaluation. The codecs were extensively tested for computational complexity and subjective (human perceived) quality, at data rates of 1.5 Mbit/s. This specific bitrate was chosen for transmission over T-1 / E-1 lines and as the approximate data rate of audio CDs . The codecs that excelled in this testing were utilized as

2079-526: The MPEG-1 standard covers systems , and is defined in ISO/IEC-11172-1. MPEG-1 Systems specifies the logical layout and methods used to store the encoded audio, video, and other data into a standard bitstream, and to maintain synchronization between the different contents. This file format is specifically designed for storage on media, and transmission over communication channels , that are considered relatively reliable. Only limited error protection

2142-515: The approved MPEG standards were revised by later amendments and/or new editions. The primary early MPEG compression formats and related standards include: MPEG-4 AVC was chosen as the video compression scheme for over-the-air television broadcasting in Brazil (ISDB-TB), based on the digital television system of Japan (ISDB-T). An MPEG-3 project was cancelled. MPEG-3 was planned to deal with standardizing scalable and multi-resolution compression and

2205-728: The background behind an object is being revealed over several frames, or in fading transitions, such as scene changes. A B-frame can contain any number of intra-coded blocks and forward-predicted blocks, in addition to backwards-predicted, or bidirectionally predicted blocks. MPEG-1 has a unique frame type not found in later video standards. "D-frames" or DC-pictures are independently coded images (intra-frames) that have been encoded using DC transform coefficients only (AC coefficients are removed when encoding D-frames—see DCT below) and hence are very low quality. D-frames are never referenced by I-, P- or B- frames. D-frames are only used for fast previews of video, for instance when seeking through

2268-420: The basis for the standard and refined further, with additional features and other improvements being incorporated in the process. After 20 meetings of the full group in various cities around the world, and 4½ years of development and testing, the final standard (for parts 1–3) was approved in early November 1992 and published a few months later. The reported completion date of the MPEG-1 standard varies greatly:

2331-405: The best-known part of the MPEG-1 standard is the first version of the MP3 audio format it introduced. The MPEG-1 standard is published as ISO / IEC 11172 , titled Information technology—Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s . The standard consists of the following five Parts : The predecessor of MPEG-1 for video coding

2394-462: The following international standards; each of the standards holds multiple MPEG technologies for a variety of applications. (For example, MPEG-A includes a number of technologies on multimedia application format.) A standard published by ISO/IEC is the last stage of an approval process that starts with the proposal of new work within a committee. Stages of the standard development process include: Other abbreviations: A proposal of work (New Proposal)

2457-524: The gstreamer-devel mailing list were able to list a single unexpired MPEG-1 Video and MPEG-1 Audio Layer I/II patent. A May 2009 discussion on the whatwg mailing list mentioned US 5,214,678 patent as possibly covering MPEG-1 Audio Layer II. Filed in 1990 and published in 1993, this patent is now expired. A full MPEG-1 decoder and encoder, with "Layer III audio", could not be implemented royalty free since there were companies that required patent fees for implementations of MPEG-1 Audio Layer III, as discussed in

2520-484: The human eye is much more sensitive to small changes in brightness (the Y component) than in color (the Cr and Cb components), chroma subsampling is a very effective way to reduce the amount of video data that needs to be compressed. However, on videos with fine detail (high spatial complexity ) this can manifest as chroma aliasing artifacts. Compared to other digital compression artifacts , this issue seems to very rarely be

2583-464: The middle of the video to reset to zero, which then begin incrementing again. Such PTS wraparound disparities can cause timing issues that must be specially handled by the decoder. Decoding Time Stamps (DTS), additionally, are required because of B-frames. With B-frames in the video stream, adjacent frames have to be encoded and decoded out-of-order (re-ordered frames). DTS is quite similar to PTS, but instead of just handling sequential frames, it contains

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2646-414: The next (such as a cut ), it is more efficient to encode it as an I-frame. "B-frame" stands for "bidirectional-frame" or "bipredictive frame". They may also be known as backwards-predicted frames or B-pictures. B-frames are quite similar to P-frames, except they can make predictions using both the previous and future frames (i.e. two anchor frames). It is therefore necessary for the player to first decode

2709-593: The next I- or P- anchor frame sequentially after the B-frame, before the B-frame can be decoded and displayed. This means decoding B-frames requires larger data buffers and causes an increased delay on both decoding and during encoding. This also necessitates the decoding time stamps (DTS) feature in the container/system stream (see above). As such, B-frames have long been subject of much controversy, they are often avoided in videos, and are sometimes not fully supported by hardware decoders. No other frames are predicted from

2772-405: The other simultaneous stream (e.g. video). The MPEG Video Buffering Verifier (VBV) assists in determining if a multiplexed PS can be decoded by a device with a specified data throughput rate and buffer size. This offers feedback to the multiplexer and the encoder, so that they can change the multiplex size or adjust bitrates as needed for compliance. Part 2 of the MPEG-1 standard covers video and

2835-407: The picture (though the extra decoded pixels are not displayed). To decrease the amount of temporal redundancy in a video, only blocks that change are updated, (up to the maximum GOP size). This is known as conditional replenishment. However, this is not very effective by itself. Movement of the objects, and/or the camera may result in large portions of the frame needing to be updated, even though only

2898-461: The position of the previously encoded objects has changed. Through motion estimation, the encoder can compensate for this movement and remove a large amount of redundant information. Profile (engineering) In standardization , a profile is a subset internal to a specification . Aspects of a complex technical specification may necessarily have more than one interpretation, and there are probably many optional features. These aspects constitute

2961-462: The profile along the centerline. A profile can also indicate the vertical slope(s) (changes in elevation) in a pipeline or similar structure. Civil engineers always depict profile as a side ( cross section ) view (as opposed to an overhead ( plan ) view). In fabricating , a profile consists of the more-or-less complex outline of a shape to be cut in a sheet of material such as laminated plastic, aluminium alloy or steel plate . In modern practice,

3024-408: The proper time-stamps to tell the decoder when to decode and display the next B-frame (types of frames explained below), ahead of its anchor (P- or I-) frame. Without B-frames in the video, PTS and DTS values are identical. To generate the PS, the multiplexer will interleave the (two or more) packetized elementary streams. This is done so the packets of the simultaneous streams can be transferred over

3087-479: The same channel and are guaranteed to both arrive at the decoder at precisely the same time. This is a case of time-division multiplexing . Determining how much data from each stream should be in each interleaved segment (the size of the interleave) is complicated, yet an important requirement. Improper interleaving will result in buffer underflows or overflows, as the receiver gets more of one stream than it can store (e.g. audio), before it gets enough data to decode

3150-402: The sole chair (after Sullivan became the chair of SC 29). The MPEG standards consist of different Parts . Each Part covers a certain aspect of the whole specification. The standards also specify profiles and levels . Profiles are intended to define a set of tools that are available, and Levels define the range of appropriate values for the properties associated with them. Some of

3213-406: The standard under development is reached, a Working Draft (WD) is produced. When a WD is sufficiently solid (typically after producing several numbered WDs), the next draft is issued as a Committee Draft (CD) (usually at the planned time) and is sent to National Bodies (NBs) for comment. When a consensus is reached to proceed to the next stage, the draft becomes a Draft International Standard (DIS) and

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3276-429: The standard which governs both permits such limitations. In structural engineering a profile means a hot rolled structural steel shape like an Ɪ-beam . In civil engineering , a profile consists of a plotted line which indicates grades and distances (and typically depths of cut and/or elevations of fill) for excavation and grading work. Constructors of roadways , railways (and similar works) normally chart

3339-502: The text is considered sufficiently mature, the WD, CD, and/or FDIS stages can be skipped. The development of a standard is completed when the FDIS document has been issued, with the FDIS stage only being for final approval, and in practice, the FDIS stage for MPEG standards has always resulted in approval. MPEG-1 MPEG-1 is a standard for lossy compression of video and audio . It

3402-684: The then-current ITU-T H.262 / MPEG-2 standard. The JVT was chaired by Dr. Gary Sullivan, with vice-chairs Dr. Thomas Wiegand of the Heinrich Hertz Institute in Germany and Dr. Ajay Luthra of Motorola in the United States. Joint Collaborative Team on Video Coding (JCT-VC) was a group of video coding experts from ITU-T Study Group 16 (VCEG) and ISO/IEC JTC 1/SC 29/WG 11 (MPEG). It was created in 2010 to develop High Efficiency Video Coding (HEVC, MPEG-H Part 2, ITU-T H.265),

3465-507: The time. MPEG-1 has several frame/picture types that serve different purposes. The most important, yet simplest, is I-frame . "I-frame" is an abbreviation for " Intra-frame ", so-called because they can be decoded independently of any other frames. They may also be known as I-pictures, or keyframes due to their somewhat similar function to the key frames used in animation. I-frames can be considered effectively identical to baseline JPEG images. High-speed seeking through an MPEG-1 video

3528-550: The video content). For this reason, D-frames are seldom actually used in MPEG-1 video encoding, and the D-frame feature has not been included in any later video coding standards. MPEG-1 operates on video in a series of 8×8 blocks for quantization. However, to reduce the bit rate needed for motion vectors and because chroma (color) is subsampled by a factor of 4, each pair of (red and blue) chroma blocks corresponds to 4 different luma blocks. That is, for 4 luma blocks of size 8x8, there

3591-464: Was appointed as Acting Convenor of SC 29/WG 11 during the restructuring period and was then appointed Convenor of SC 29's Advisory Group 2, which coordinates MPEG overall technical activities. The MPEG structure that replaced the former Working Group 11 includes three Advisory Groups (AGs) and seven Working Groups (WGs) The first meeting under the current structure was held in August 2024, with MPEG 147 MPEG-2 development included

3654-482: Was intended for HDTV compression, but was found to be unnecessary and was merged with MPEG-2; as a result there is no MPEG-3 standard. The cancelled MPEG-3 project is not to be confused with MP3 , which is MPEG-1 or MPEG-2 Audio Layer III. In addition, the following standards, while not sequential advances to the video encoding standard as with MPEG-1 through MPEG-4, are referred to by similar notation: Moreover, more recently than other standards above, MPEG has produced

3717-399: Was joint project between ITU-T SG16 /Q.6 (Study Group 16 / Question 6) – VCEG (Video Coding Experts Group) and ISO/IEC JTC 1/SC 29/WG 11 – MPEG for the development of a video coding ITU-T Recommendation and ISO/IEC International Standard. It was formed in 2001 and its main result was H.264/MPEG-4 AVC (MPEG-4 Part 10), which reduces the data rate for video coding by about 50%, as compared to

3780-519: Was later audited by ATR-M audio group, after an exploration phase that began in 2015. JVET developed Versatile Video Coding (VVC, MPEG-I Part 3, ITU-T H.266), completed in July 2020, which further reduces the data rate for video coding by about 50%, as compared to the then-current ITU-T H.265 / HEVC standard, and the JCT-VC was merged into JVET in July 2020. Like JCT-VC, JVET was co-chaired by Jens-Rainer Ohm and Gary Sullivan, until July 2021 when Ohm became

3843-648: Was the H.261 standard produced by the CCITT (now known as the ITU-T ). The basic architecture established in H.261 was the motion-compensated DCT hybrid video coding structure. It uses macroblocks of size 16×16 with block-based motion estimation in the encoder and motion compensation using encoder-selected motion vectors in the decoder, with residual difference coding using a discrete cosine transform (DCT) of size 8×8, scalar quantization , and variable-length codes (like Huffman codes ) for entropy coding . H.261

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3906-542: Was the first practical video coding standard, and all of its described design elements were also used in MPEG-1. Modeled on the successful collaborative approach and the compression technologies developed by the Joint Photographic Experts Group and CCITT 's Experts Group on Telephony (creators of the JPEG image compression standard and the H.261 standard for video conferencing respectively),

3969-572: Was the group's chair (called Convenor in ISO/IEC terminology) from its inception until June 6, 2020. The first MPEG meeting was in May 1988 in Ottawa, Canada . Starting around the time of the MPEG-4 project in the late 1990s and continuing to the present, MPEG had grown to include approximately 300–500 members per meeting from various industries, universities, and research institutions. On June 6, 2020,

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