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39-625: The ISO standard ISO 8859 was the first international standard to formalise a (limited) expansion of the ASCII character set: of the many language variants it encoded, ISO 8859-1 ("ISO Latin 1") – which supports most Western European languages – is best known in the West. There are many other extended ASCII encodings (more than 220 DOS and Windows codepages ). EBCDIC ("the other" major character code) likewise developed many extended variants (more than 186 EBCDIC codepages) over

78-405: A lossy process , introducing generation loss ; however, transcoding can be lossless if the output is either losslessly compressed or uncompressed. The process of transcoding into a lossy format introduces varying degrees of generation loss , while the transcoding from lossy to lossless or uncompressed is technically a lossless conversion because no information is lost; however, when the conversion

117-518: A 2x3 grid of pixels, with each block pixel effectively controlled by one of the lower 6 bits.) IBM introduced eight-bit extended ASCII codes on the original IBM PC and later produced variations for different languages and cultures. IBM called such character sets code pages and assigned numbers to both those they themselves invented as well as many invented and used by other manufacturers. Accordingly, character sets are very often indicated by their IBM code page number. In ASCII-compatible code pages,

156-586: A combination of languages such as English and French (though French computers usually use code page 850 ), but not, for example, in English and Greek (which required code page 737 ). Apple Computer introduced their own eight-bit extended ASCII codes in Mac OS , such as Mac OS Roman . The Apple LaserWriter also introduced the Postscript character set . Digital Equipment Corporation (DEC) developed

195-403: A common format for digital cinema , but the data size of a two-hour movie is about 8 terabytes (TB). That large size can increase the cost and difficulty of handling movie files. However, transcoding into a JPEG2000 lossless format has better compression performance than other lossless coding technologies, and in many cases, JPEG2000 can compress images to half-size. Transcoding is commonly

234-426: A different format and smaller file size, to be transcoded only from that master copy. Although transcoding can be found in many areas of content adaptation, it is commonly used in the area of mobile phone content adaptation. In this case, transcoding is a must, due to the diversity of mobile devices and their capabilities. This diversity requires an intermediate state of content adaptation in order to make sure that

273-451: A lower resolution image with fewer colors in order to better fit the target device's screen size and color limitations. This size and color reduction improves the user experience on the target device, and is sometimes the only way for content to be sent between different mobile devices. Transcoding is extensively used by home theatre PC software to reduce the usage of disk space by video files. The most common operation in this application

312-475: A subsequent loss of quality. For image editing users are advised to capture or save images in a raw or uncompressed format, and then edit a copy of that master version, only converting to lossy formats if smaller file sized images are needed for final distribution. As with audio, transcoding from lossy format to another format of any type will result in a loss of quality. For video editing , (for video converting), images are normally compressed directly during

351-463: A time, returning to an idle state immediately afterward; this meant that any control sequences had to be only one character long, and thus a large number of codes needed to be reserved for such controls. They were typewriter-derived impact printers , and could only print a fixed set of glyphs, which were cast into a metal type element or elements; this also encouraged a minimum set of glyphs. Seven-bit ASCII improved over prior five- and six-bit codes. Of

390-514: Is barely large enough for US English use and lacks many glyphs common in typesetting , and far too small for universal use. Many more letters and symbols are desirable, useful, or required to directly represent letters of alphabets other than English, more kinds of punctuation and spacing, more mathematical operators and symbols (× ÷ ⋅ ≠ ≥ ≈ π etc.), some unique symbols used by some programming languages, ideograms , logograms , box-drawing characters, etc. The biggest problem for computer users around

429-417: Is generally discouraged unless unavoidable. For users wanting to be able to re-encode audio into any format, and for digital audio editing , it is best to retain a master copy in a lossless format (such as FLAC , ALAC , TTA, WavPack , and others) that take around half the storage space needed when compared to original uncompressed PCM formats (such as WAV , and AIFF ), as lossless formats usually have

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468-426: Is irreversible, it is then more correctly known as destructive . Transcoding is a two-step process in which the original data is decoded to an intermediate uncompressed format (e.g., PCM for audio; YUV for video), which is then encoded into the target format. One may also re-encode data in the same format, for a number of reasons: One can also use formats with bitrate peeling , that allow one to easily lower

507-420: Is specified. The meaning of each extended code point can be different in every encoding. In order to correctly interpret and display text data (sequences of characters) that includes extended codes, hardware and software that reads or receives the text must use the specific extended ASCII encoding that applies to it. Applying the wrong encoding causes irrational substitution of many or all extended characters in

546-533: Is still not enough to cover all purposes, all languages, or even all European languages, so the emergence of many proprietary and national ASCII-derived 8-bit character sets was inevitable. Translating between these sets ( transcoding ) is complex (especially if a character is not in both sets); and was often not done, producing mojibake (semi-readable resulting text, often users learned how to manually decode it). There were eventually attempts at cooperation or coordination by national and international standards bodies in

585-511: Is that the 32 character positions 80 16 to 9F 16 , which correspond to the ASCII control characters with the high-order bit 'set', are reserved by ISO for control use and unused for printable characters (they are also reserved in Unicode). This convention was almost universally ignored by other extended ASCII sets. Microsoft intended to use ISO 8859 standards in Windows, but soon replaced

624-543: Is the transcoding of MPEG-2 files to the MPEG-4 or H.264 format. Real-time transcoding in a many-to-many way (any input format to any output format) is becoming a necessity to provide true search capability for any multimedia content on any mobile device, with over 500 million videos on the web and a plethora of mobile devices. Before the advent of semiconductors and integrated circuits, realtime resolution and frame rate transcoding between different analog video standards

663-429: Is usually done in cases where a target device (or workflow ) does not support the format or has limited storage capacity that mandates a reduced file size, or to convert incompatible or obsolete data to a better-supported or modern format. In the analog video world, transcoding can be performed just while files are being searched, as well as for presentation. For example, Cineon and DPX files have been widely used as

702-775: The Multinational Character Set , which had fewer characters but more letter and diacritic combinations. It was supported by the VT220 and later DEC computer terminals . This later became the basis for other character sets such as the Lotus International Character Set (LICS), ECMA-94 and ISO 8859-1 . In 1987, the International Organization for Standardization (ISO) published a set of standards for eight-bit ASCII extensions, ISO 8859. The most popular of these

741-431: The backspace control between them) to produce accented letters. Users were not comfortable with any of these compromises and they were often poorly supported. When computers and peripherals standardized on eight-bit bytes in the 1970s, it became obvious that computers and software could handle text that uses 256-character sets at almost no additional cost in programming, and no additional cost for storage. (Assuming that

780-698: The 2=128 codes, 33 were used for controls, and 95 carefully selected printable characters (94 glyphs and one space), which include the English alphabet (uppercase and lowercase), digits, and 31 punctuation marks and symbols: all of the symbols on a standard US typewriter plus a few selected for programming tasks. Some popular peripherals only implemented a 64-printing-character subset: Teletype Model 33 could not transmit "a" through "z" or five less-common symbols ("`", "{", "|", "}", and "~"). and when they received such characters they instead printed "A" through "Z" (forced all caps ) and five other mostly-similar symbols ("@", "[", "\", "]", and "^"). The ASCII character set

819-566: The Wikimedia System Administrators, please include the details below. Request from 172.68.168.132 via cp1112 cp1112, Varnish XID 944485008 Upstream caches: cp1112 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 08:46:01 GMT Transcoding Transcoding is the direct digital-to-digital conversion of one encoding to another, such as for video data files, audio files (e.g., MP3 , WAV ), or character encoding (e.g., UTF-8 , ISO/IEC 8859 ). This

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858-492: The added benefit of having meta data options, which are either completely missing or very limited in PCM formats. These lossless formats can be transcoded to PCM formats or transcoded directly from one lossless format to another lossless format, without any loss in quality. They can be transcoded into a lossy format, but these copies will then not be able to be transcoded into another format of any kind (PCM, lossless, or lossy) without

897-504: The bitrate without re-encoding, but quality is often lower than a re-encode. For example, in Vorbis bitrate peeling as of 2008, the quality is inferior to re-encoding. The key drawback of transcoding in lossy formats is decreased quality. Compression artifacts are cumulative, so transcoding causes a progressive loss of quality with each successive generation, known as digital generation loss . For this reason, transcoding (in lossy formats)

936-468: The code page 1252 superset of ISO 8859-1) is the dominant operating system for personal computers today, unannounced use of ISO 8859-1 is quite commonplace, and may generally be assumed unless there are indications otherwise. Many communications protocols , most importantly SMTP and HTTP , require the character encoding of content to be tagged with IANA -assigned character set identifiers. ISO 8859 Too Many Requests If you report this error to

975-642: The decades. All modern operating systems use Unicode which supports thousands of characters. However, extended ASCII remains important in the history of computing , and supporting multiple extended ASCII character sets required software to be written in ways that made it much easier to support the UTF-8 encoding method later on. ASCII was designed in the 1960s for teleprinters and telegraphy , and some computing. Early teleprinters were electromechanical, having no microprocessor and just enough electromechanical memory to function. They fully processed one character at

1014-576: The late 1990s, but manufacturer-proprietary sets remained the most popular by far, primarily because the international standards excluded characters popular in or peculiar to specific cultures. Various proprietary modifications and extensions of ASCII appeared on non- EBCDIC mainframe computers and minicomputers , especially in universities. Hewlett-Packard started to add European characters to their extended 7-bit / 8-bit ASCII character set HP Roman Extension around 1978/1979 for use with their workstations, terminals and printers. This later evolved into

1053-527: The lower 128 characters maintained their standard ASCII values, and different pages (or sets of characters) could be made available in the upper 128 characters. DOS computers built for the North American market, for example, used code page 437 , which included accented characters needed for French, German, and a few other European languages, as well as some graphical line-drawing characters. The larger character set made it possible to create documents in

1092-536: The most popular technologies in which transcoding is used is the Multimedia Messaging Service (MMS), which is the technology used to send or receive messages with media (image, sound, text and video) between mobile phones. For example, when a camera phone is used to take a digital picture, a high-quality image of usually at least 640x480 pixels is created. When sending the image to another phone, this high resolution image might be transcoded to

1131-442: The recording process due to the huge file sizes that would be created if they were not, and because the huge storage demands being too cumbersome for the user otherwise. However, the amount of compression used at the recording stage can be highly variable, and is dependent on a number of factors, including the quality of images being recorded (e.g. analog or digital, standard def. or high def., etc.), and type of equipment available to

1170-570: The replaced characters, work-arounds were devised such as C three-character sequences "??<" and "??>" to represent "{" and "}". Languages with dissimilar basic alphabets could use transliteration, such as replacing all the Latin letters with the closest match Cyrillic letters (resulting in odd but somewhat readable text when English was printed in Cyrillic or vice versa). Schemes were also devised so that two letters could be overprinted (often with

1209-405: The source content will adequately function on the target device to which it is sent. Transcoding video from most consumer digital cameras can reduce the file size significantly while keeping the quality about the same. This is possible because most consumer cameras are real-time , power-constrained devices having neither the processing power nor the robust power supplies of desktop CPUs. One of

Extended ASCII - Misplaced Pages Continue

1248-433: The text. Software can use a fixed encoding selection, or it can select from a palette of encodings by defaulting, checking the computer's nation and language settings, reading a declaration in the text, analyzing the text , asking the user, letting the user select or override, and/or defaulting to last selection. When text is transferred between computers that use different operating systems, software, and encodings, applying

1287-586: The unused 8th bit of each byte was not reused in some way, such as error checking, Boolean fields, or packing 8 characters into 7 bytes.) This would allow ASCII to be used unchanged and provide 128 more characters. Many manufacturers devised 8-bit character sets consisting of ASCII plus up to 128 of the unused codes: encodings which covered all the more used Western European (and Latin American) languages, such as Danish, Dutch, French, German, Portuguese, Spanish, Swedish and more could be made. 128 additional characters

1326-420: The unused C1 control characters with additional characters, making the proprietary Windows-1252 character set, which is sometimes mislabeled as ANSI . The added characters included "curly" quotation marks and other typographical elements like em dash , the euro sign , and letters missing from French and Finnish. This became the most-used extended ASCII in the world, and often is used on the web even when 8859-1

1365-429: The user, which is often related to budget constraints – as highest quality digital video equipment, and storage space, may be expensive. Effectively this means that any transcoding will involve some cumulative image loss, and hence the most practical solution insofar as minimizing loss of quality is for the original recording to be deemed the master copy, and for desired subsequent transcoded versions, which will often be in

1404-552: The widely used regular 8-bit character sets HP Roman-8 and HP Roman-9 (as well as a number of variants). Atari and Commodore home computers added many graphic symbols to their non-standard ASCII (Respectively, ATASCII and PETSCII , based on the original ASCII standard of 1963). The TRS-80 character set for the TRS-80 home computer added 64 semigraphics characters (0x80 through 0xBF) that implemented low-resolution block graphics. (Each block-graphic character displayed as

1443-719: The world was other alphabets. ASCII's English alphabet almost accommodates European languages, if accented letters are replaced by non-accented letters or two-character approximations such as ss for ß . Modified variants of 7-bit ASCII appeared promptly, trading some lesser-used symbols for highly desired symbols or letters, such as replacing "#" with "£" on UK Teletypes, "\" with "¥" in Japan or "₩" in Korea, etc. At least 29 variant sets resulted. 12 code points were modified by at least one modified set, leaving only 82 "invariant" codes . Programming languages however had assigned meaning to many of

1482-477: The wrong encoding can be commonplace. Because the full English alphabet and the most-used characters in English are included in the seven-bit code points of ASCII, which are common to all encodings (even most proprietary encodings), English-language text is less damaged by interpreting it with the wrong encoding, but text in other languages can display as mojibake (complete nonsense). Because many Internet standards use ISO 8859-1, and because Microsoft Windows (using

1521-566: Was ISO 8859-1 (also called "ISO Latin 1") which contains characters sufficient for the most common Western European languages. Other standards in the 8859 group included ISO 8859-2 for Eastern European languages using the Latin script and ISO 8859-5 for languages using the Cyrillic script , and others. One notable way in which the ISO standards differ from some vendor-specific extended ASCII

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