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93-458: As the word "common" in its name implies, CIF was designed as a common compromise format to be relatively easy to convert for use either with PAL or NTSC standard displays and cameras. CIF defines a video sequence with a resolution of 352 × 288, which has a simple relationship to the PAL picture size, but with a frame rate of 30000/1001 (roughly 29.97) frames per second like NTSC, with color encoded using

186-429: A YCbCr representation with 4:2:0 color sampling. It was designed as a compromise between PAL and NTSC schemes, since it uses a picture size that corresponds most easily to PAL, but uses the frame rate of NTSC. The compromise was established as a way to reach international agreement so that video conferencing systems in different countries could communicate with each other without needing two separate modes for displaying

279-672: A "Bruch system" would probably not have sold very well ("Bruch" is the German word for "breakage" ). The first broadcasts began in the United Kingdom in July 1967, followed by West Germany at the Berlin IFA on August 25. The BBC channel initially using the broadcast standard was BBC2 , which had been the first UK TV service to introduce "625-lines" during 1964. The Netherlands and Switzerland started PAL broadcasts by 1968, with Austria following

372-432: A 4:3 area, in order to avoid a "stretched" look: CIF content expanded horizontally by 12:11 results in a 4:3 raster of 384 × 288 square pixels (384 = 352 * 12/11). (This can happen on larger graphics displays of any aspect ratio in a window of 384 × 288 square pixels or enlarged to full screen on any larger 4:3 graphic display.) The CIF and QCIF picture dimensions were specifically chosen to be multiples of 16 because of

465-410: A 6 MHz channel with a chrominance subcarrier frequency of 3.582056 MHz (917/4*H) similar to NTSC (910/4*H). On the studio production level, standard PAL cameras and equipment were used, with video signals then transcoded to PAL-N for broadcast. This allows 625 line, 50 frames per second video to be broadcast in a 6 MHz channel, at some cost in horizontal resolution . In Brazil, PAL

558-414: 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

651-584: A European signal. The BBC tested their pre-war (but still broadcast until 1985) 405-line monochrome system ( CCIR System A ) with all three colour standards including PAL, before the decision was made to abandon 405 and transmit colour on 625/ System I only. Many countries have turned off analogue transmissions, so the following does not apply anymore, except for using devices which output RF signals, such as video recorders . The majority of countries using or having used PAL have television standards with 625 lines and 50 fields per second. Differences concern

744-506: 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"

837-865: A PAL-N TV broadcast can be sent to anyone in European countries that use PAL (and Australia/New Zealand, etc.) and it will display in colour. This will also play back successfully in Russia and other SECAM countries, as the USSR mandated PAL compatibility in 1985—this has proved to be very convenient for video collectors. People in Argentina, Paraguay and Uruguay usually own TV sets that also display NTSC-M, in addition to PAL-N. DirecTV also conveniently broadcasts in NTSC-M for North, Central, and South America. Most DVD players sold in Argentina, Paraguay and Uruguay also play PAL discs—however, this

930-458: 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

1023-423: A comb-like effect known as Hanover bars on larger phase errors. Thus, most receivers now use a chrominance analogue delay line , which stores the received colour information on each line of display; an average of the colour information from the previous line and the current line is then used to drive the picture tube . The effect is that phase errors result in saturation changes, which are less objectionable than

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1116-527: A delay line and suffering from the “ Hanover bars ” effect. An example of this solution is the Kuba Porta Color CK211P set. Another solution was to use a 1H analogue delay line to allow decoding of only the odd or even lines. For example, the chrominance on odd lines would be switched directly through to the decoder and also be stored in the delay line. Then, on even lines, the stored odd line would be decoded again. This method (known as 'gated NTSC')

1209-524: A frame rate of 25 frames per second. Some references to CIF are intended to refer only to its resolution (352 × 288), without intending to refer to its frame rate. The YCbCr color representation had been previously defined in the first standard digital video source format, CCIR 601 , in 1982. However, CCIR 601 uses 4:2:2 color sampling, which subsamples the Cb and Cr components only horizontally. H.261 additionally used vertical color subsampling, resulting in what

1302-587: 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

1395-405: A major issue considering Europe's geographical and weather-related particularities. To overcome NTSC's shortcomings, alternative standards were devised, resulting in the development of the PAL and SECAM standards. The goal was to provide a colour TV standard for the European picture frequency of 50  fields per second (50  hertz ), and finding a way to eliminate the problems with NTSC. PAL

1488-410: 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

1581-408: 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

1674-470: A quasi-unique positive video modulation, system L) unless they are manufactured for the French market. They will correctly display plain (non-broadcast) CVBS or S-video SECAM signals. Many can also accept baseband NTSC-M, such as from a VCR or game console, and RF modulated NTSC with a PAL standard audio subcarrier (i.e., from a modulator), though not usually broadcast NTSC (as its 4.5 MHz audio subcarrier

1767-431: 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

1860-477: 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

1953-691: 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

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2046-457: 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

2139-658: A typical bandwidth of 1.3 MHz. Composite PAL signal = E ′ Y + E ′ U sin ⁡ ( ω t ) + E ′ V cos ⁡ ( ω t ) + {\displaystyle =E'{\scriptstyle {\text{Y}}}+E'{\scriptstyle {\text{U}}}\sin(\omega t)+E'{\scriptstyle {\text{V}}}\cos(\omega t)+} timing where ω = 2 π F S C {\displaystyle \omega =2\pi F_{SC}} . Subcarrier frequency F S C {\displaystyle F_{SC}}

2232-470: 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

2325-416: A ″native″ aspect ratio ( pixel aspect ratio (PAR) ) of 12:11 (PAR = DAR  :  SAR  = ⁠ 4 / 3 ⁠  :  ⁠ 11 / 9 ⁠  =  ⁠ 12 / 11 ⁠ ), as with the standard for 625-line systems (see CCIR 601 ). On square-pixel displays (e.g., computer screens and many modern televisions) xCIF rasters should be rescaled so that the picture covers

2418-411: Is composite video because luminance (luma, monochrome image) and chrominance (chroma, colour applied to the monochrome image) are transmitted together as one signal. A latter evolution of the standard, PALplus , added support for widescreen broadcasts with no loss of vertical image resolution , while retaining compatibility with existing sets. Almost all of the countries using PAL are currently in

2511-462: Is 100% for white level, 30% for black, and 0% for sync. The CVBS electrical amplitude is Vpp 1.0  V and impedance of 75 Ω . The vertical timings are: (Total vertical sync time 1.6 ms) As PAL is interlaced, every two fields are summed to make a complete picture frame. PAL colorimetry, as defined by the ITU on REC-BT.470, and based on CIE 1931 x,y coordinates: The assumed display gamma

2604-426: Is 4.43361875  MHz for PAL 4.43, compared to 3.579545 MHz for NTSC 3.58. The SECAM system, on the other hand, uses a frequency modulation scheme on its two line alternate colour subcarriers 4.25000 and 4.40625 MHz. The name "Phase Alternating Line" describes the way that the phase of part of the colour information on the video signal is reversed with each line, which automatically corrects phase errors in

2697-441: Is 4.43361875 MHz (±5 Hz) for PAL-B/D/G/H/I/N. The PAL colour system is usually used with a video format that has 625 lines per frame (576 visible lines, the rest being used for other information such as sync data and captioning) and a refresh rate of 50  interlaced fields per second (compatible with 25 full frames per second), such systems being B , G , H , I , and N (see broadcast television systems for

2790-475: Is a colour encoding system for analog television . It was one of three major analogue colour television standards, the others being NTSC and SECAM . In most countries it was broadcast at 625 lines , 50 fields (25 frames) per second, and associated with CCIR analogue broadcast television systems B , D , G , H , I or K . The articles on analog broadcast television systems further describe frame rates , image resolution , and audio modulation. PAL video

2883-449: 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

Common Intermediate Format - Misplaced Pages Continue

2976-402: 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

3069-949: Is defined as 2.8. The PAL-M system uses color primary and gamma values similar to NTSC. Color is encoded using the YUV color space. Luma ( E ′ Y {\displaystyle E'{\scriptstyle {\text{Y}}}} ) is derived from red, green, and blue ( E ′ R , E ′ G , E ′ B {\displaystyle E'{\scriptstyle {\text{R}}},E'{\scriptstyle {\text{G}}},E'{\scriptstyle {\text{B}}}} ) gamma pre-corrected ( E ′ {\displaystyle E'} ) primary signals: E ′ U {\displaystyle E'{\scriptstyle {\text{U}}}} and E ′ V {\displaystyle E'{\scriptstyle {\text{V}}}} are used to transmit chrominance . Each has

3162-562: 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

3255-465: 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

3348-442: 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

3441-402: Is known as 4:2:0. QCIF means "Quarter CIF". To have one quarter of the area, as "quarter" implies, the height and width of the frame are halved. Terms also used are SQCIF (Sub Quarter CIF, sometimes Sub-QCIF ), 4CIF (4 × CIF), 9CIF (9 × CIF) and 16CIF (16 × CIF). The resolutions for all of these formats are summarized in the table below. xCIF pixels are not square, instead having

3534-436: 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

3627-522: Is not supported). Many sets also support NTSC with a 4.43 MHz color subcarrier (see PAL 60 on the next section). VHS tapes recorded from a PAL-N or a PAL-B/G, D/K, H, or I broadcast are indistinguishable because the downconverted subcarrier on the tape is the same. A VHS recorded off TV (or released) in Europe will play in colour on any PAL-N VCR and PAL-N TV in Argentina, Paraguay and Uruguay. Likewise, any tape recorded in Argentina, Paraguay or Uruguay off

3720-470: Is often known as "PAL 60" (sometimes "PAL 60/525", "Quasi-PAL" or "Pseudo PAL"). PAL-M (a broadcast standard) however should not be confused with "PAL 60" (a video playback system—see below). PAL television receivers manufactured since the 1990s can typically decode all of the PAL variants except, in some cases PAL-M and PAL-N. Many such receivers can also receive Eastern European and Middle Eastern SECAM, though rarely French-broadcast SECAM (because France used

3813-524: 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

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3906-484: 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

3999-506: Is only used on UHF. Although System I is used on both bands, it has only been used on UHF in the United Kingdom. The PAL-L (Phase Alternating Line with CCIR System L broadcast system) standard uses the same video system as PAL-B/G/H (625 lines, 50 Hz field rate, 15.625 kHz line rate), but with a larger 6 MHz video bandwidth rather than 5.5 MHz and moving the audio subcarrier to 6.5 MHz. An 8 MHz channel spacing

4092-486: Is used for PAL-L, to maintain compatibility with System L channel spacings. The PAL-N standard was created in Argentina , through Resolution No. 100 ME/76, which determined the creation of a study commission for a national color standard. The commission recommended using PAL under CCIR System N that Paraguay and Uruguay also used. It employs the 625 line/50 field per second waveform of PAL-B/G, D/K, H, and I, but on

4185-537: Is used in conjunction with the 525 line, 60 field/s CCIR System M , using (very nearly) the NTSC colour subcarrier frequency. Exact colour subcarrier frequency of PAL-M is 3.575611 MHz, or 227.25 times System M's horizontal scan frequency. Almost all other countries using system M use NTSC. The PAL colour system (either baseband or with any RF system, with the normal 4.43 MHz subcarrier unlike PAL-M) can also be applied to an NTSC-like 525-line picture to form what

4278-623: Is usually mentioned as "PAL" (eg: "PAL DVD"). Likewise, video game consoles outputting a 50 Hz signal might be labeled as "PAL", as opposed to 60 Hz on NTSC machines. These designations should not be confused with the analog colour system itself. In the 1950s, the Western European countries began plans to introduce colour television, and were faced with the problem that the NTSC standard demonstrated several weaknesses, including colour tone shifting under poor transmission conditions, which became

4371-547: Is usually output in the European variant (colour subcarrier frequency 4.433618 MHz), so people who own a TV set which only works in PAL-N (plus NTSC-M in most cases) will have to watch those PAL DVD imports in black and white (unless the TV supports RGB SCART ) as the colour subcarrier frequency in the TV set is the PAL-N variation, 3.582056 MHz. MPEG-1 MPEG-1 is a standard for lossy compression of video and audio . It

4464-484: 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

4557-402: The 625-line /50 Hz television system in general, to differentiate from the 525-line /60 Hz system generally used with NTSC. For example, DVDs were labelled as PAL or NTSC (referring to the line count and frame rate) even though technically the discs carry neither PAL nor NTSC encoded signal. These devices would still have analog outputs (ex; composite video output), and would convert

4650-606: 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

4743-575: 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

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4836-476: The Philippines , and Taiwan . With the introduction of home video releases and later digital sources (e.g. DVD-Video ), the name "PAL" might be used to refer to digital formats, even though they use completely different colour encoding systems. For instance, 576i (576 interlaced lines) digital video with colour encoded as YCbCr , intended to be backward compatible and easily displayed on legacy PAL devices,

4929-543: The RCA brand and licences it to other companies; Radio Corporation of America , the originator of that brand, created the NTSC colour TV standard before Thomson became involved. The Soviets developed two further systems, mixing concepts from PAL and SECAM, known as TRIPAL and NIIR, that never went beyond tests. In 1993, an evolution of PAL aimed to improve and enhance format by allowing 16:9 aspect ratio broadcasts, while remaining compatible with existing television receivers,

5022-587: 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

5115-639: The process of conversion , or have already converted transmission standards to DVB , ISDB or DTMB . The PAL designation continues to be used in some non-broadcast contexts, especially regarding console video games . PAL was adopted by most European countries, by several African countries, by Argentina , Brazil , Paraguay , Uruguay , and by most of Asia Pacific (including the Middle East and South Asia) . Countries in those regions that did not adopt PAL were France , Francophone Africa, several ex- Soviet states, Japan , South Korea , Liberia , Myanmar ,

5208-545: The CIF compromise that originated with the H.261 standard, there are two variants of the SIF ( Source Input Format ) that was first defined in the MPEG-1 standard. SIF is otherwise very similar to CIF. SIF on 525-line ("NTSC") based systems is 352 × 240 with a frame rate of 30000/1001 frames per second, and on 625-line ("PAL") based systems, it has the same picture size as CIF (352 × 288) but with

5301-531: 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

5394-519: 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

5487-481: The alternating subcarrier phase to reduce phase errors, described as " PAL-D " for "delay", and " PAL-N " for "new" or " Chrominance Lock ". This excluded very basic PAL decoders that relied on the human eye to average out the odd/even line phase errors, and in the early 1970s some Japanese set manufacturers developed basic decoding systems to avoid paying royalties to Telefunken . These variations are known as " PAL-S " (for "simple" or "Volks-PAL"), operating without

5580-399: The audio carrier frequency and channel bandwidths. The variants are: Systems B and G are similar. System B specifies 7 MHz channel bandwidth, while System G specifies 8 MHz channel bandwidth. Australia and China used Systems B and D respectively for VHF and UHF channels. Similarly, Systems D and K are similar except for the bands they use: System D is only used on VHF, while System K

5673-728: 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

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5766-420: 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:

5859-405: 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

5952-411: The colour carrier is a result of 283.75 colour clock cycles per line plus a 25 Hz offset to avoid interferences. Since the line frequency (number of lines per second) is 15625 Hz (625 lines × 50 Hz ÷ 2), the colour carrier frequency calculates as follows: 4.43361875 MHz = 283.75 × 15625 Hz + 25 Hz. The frequency 50 Hz is the optional refresh frequency of

6045-415: The colour decoder circuitry to distinguish the phase of the R − Y ′ {\displaystyle R-Y'} vector which reverses every line. For PAL-B/G the signal has these characteristics. (Total horizontal sync time 12.05 μs) After 0.9 μs a 2.25 ± 0.23 μs colourburst of 10 ± 1 cycles is sent. Most rise/fall times are in 250 ± 50  ns range. Amplitude

6138-508: The digital signals ( 576i or 480i ) to the analog standards to assure compatibility. CCIR 625/50 and EIA 525/60 are the proper names for these (line count and field rate) standards; PAL and NTSC on the other hand are methods of encoding colour information in the signal. "PAL-D", "PAL-N", "PAL-H" and "PAL-K" designations on this section describe PAL decoding methods and are unrelated to broadcast systems with similar names. The Telefunken licence covered any decoding method that relied on

6231-433: The equivalent hue changes of NTSC. A minor drawback is that the vertical colour resolution is poorer than the NTSC system's, but since the human eye also has a colour resolution that is much lower than its brightness resolution, this effect is not visible. In any case, NTSC, PAL, and SECAM all have chrominance bandwidth (horizontal colour detail) reduced greatly compared to the luma signal. The 4.43361875 MHz frequency of

6324-473: The frame rate by skipping or repeating frames as necessary. Since H.261 systems typically operated at low bit rates , they also typically operated at low frame rates by skipping many of the camera source frames, so introducing some jitter in the frame rate tended not to be noticeable. More sophisticated conversion schemes (e.g., using deinterlacing to improve the vertical resolution from an NTSC camera) could also be used in higher quality systems. In contrast to

6417-524: 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

6510-481: 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

6603-464: 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

6696-432: The monitor to be able to create an illusion of motion, while 625 lines means the vertical lines or resolution that the PAL system supports. The original colour carrier is required by the colour decoder to recreate the colour difference signals. Since the carrier is not transmitted with the video information it has to be generated locally in the receiver. In order that the phase of this locally generated signal can match

6789-400: The monochrome luma signal, with the three RGB colour channels mixed down onto two, U {\displaystyle U} and V {\displaystyle V} . Like NTSC, PAL uses a quadrature amplitude modulated subcarrier carrying the chrominance information added to the luma video signal to form a composite video baseband signal. The frequency of this subcarrier

6882-414: 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

6975-588: 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

7068-486: The next year. Telefunken PALcolour 708T was the first PAL commercial TV set. It was followed by Loewe -Farbfernseher S 920 and F 900 . Telefunken was later bought by the French electronics manufacturer Thomson . Thomson also bought the Compagnie Générale de Télévision where Henri de France developed SECAM, the first European Standard for colour television. Thomson, now called Technicolour SA, also owns

7161-405: 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

7254-407: 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

7347-408: 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

7440-483: The received video. The simple way to convert NTSC video to CIF is to capture every other field (e.g., the top fields) of interlaced video , downsample it by 2:1 horizontally to convert 704 samples per line to 352 samples per line, and upsample it vertically by a ratio of 6:5 vertically to convert 240 lines to 288 lines. The simple way to convert PAL video to CIF is to similarly capture every other field, downsample it horizontally by 2:1, and introduce some jitter in

7533-479: 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

7626-514: The same, resulting in the different sound carrier. Instead, other European countries have changed completely from SECAM-D/K to PAL-B/G. The PAL-N system has a different sound carrier, and also a different colour subcarrier, and decoding on incompatible PAL systems results in a black-and-white image without sound. The PAL-M system has a different sound carrier and a different colour subcarrier, and does not use 625 lines or 50 frames/second. This would result in no video or audio at all when viewing

7719-542: The technical details of each format). This ensures video interoperability. However, as some of these standards ( B/G/H , I and D/K ) use different sound carriers (5.5 MHz, 6.0 MHz and 6.5 MHz respectively), it may result in a video image without audio when viewing a signal broadcast over the air or cable. Some countries in Eastern Europe which formerly used SECAM with systems D and K have switched to PAL while leaving other aspects of their video system

7812-507: 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

7905-405: The transmission of the signal by cancelling them out, at the expense of vertical frame colour resolution. Lines where the colour phase is reversed compared to NTSC are often called PAL or phase-alternation lines, which justifies one of the expansions of the acronym, while the other lines are called NTSC lines. Early PAL receivers relied on the human eye to do that cancelling; however, this resulted in

7998-412: The transmitted information, a 10 cycle burst of colour subcarrier is added to the video signal shortly after the line sync pulse, but before the picture information, during the so-called back porch . This colour burst is not actually in phase with the original colour subcarrier, but leads it by 45 degrees on the odd lines and lags it by 45 degrees on the even lines. This swinging burst enables

8091-545: 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

8184-487: The way that discrete cosine transform based video compression/decompression was handled in H.261, using 16 × 16 macroblocks and 8 × 8 transform blocks. So a CIF-size image (352 × 288) contains 22 × 18 macroblocks and a QCIF image (176 × 144) contains 11 × 9 macroblocks. The 16 × 16 macroblock concept was later also used in other compression standards such as MPEG-1 , MPEG-2 , MPEG-4 Part 2 , H.263 , and H.264/MPEG-4 AVC . PAL Phase Alternating Line ( PAL )

8277-484: Was adopted by Sony on their 1970s Trinitron sets ( KV-1300UB to KV-1330UB ), and came in two versions: " PAL-H " and " PAL-K " (averaging over multiple lines). It effectively treated PAL as NTSC, suffering from hue errors and other problems inherent in NTSC and required the addition of a manual hue control. Most PAL systems encode the colour information using a variant of the Y'UV colour space. Y ′ {\displaystyle Y'} comprises

8370-572: Was developed by Walter Bruch at Telefunken in Hanover , West Germany , with important input from Gerhard Mahler  [ de ] . The format was patented by Telefunken in December 1962, citing Bruch as inventor, and unveiled to members of the European Broadcasting Union (EBU) on 3 January 1963. When asked why the system was named "PAL" and not "Bruch", the inventor answered that

8463-525: Was introduced. Named PALplus , it was defined by ITU recommendation BT.1197-1. It was developed at the University of Dortmund in Germany , in cooperation with German terrestrial broadcasters and European and Japanese manufacturers. Adoption was limited to European countries. With the introduction of digital broadcasts and signal sources (ex: DVDs , game consoles), the term PAL was used imprecisely to refer to

8556-640: 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

8649-525: 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),

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