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Encyclopedia > DVI file format

DVI ("DeVice Independent") is the output file format of the TeX typesetting program, designed by Donald Knuth in 1979. Unlike the TeX markup files used to generate them, DVI files are not intended to be human-readable; they consist of binary data describing the visual layout of a document in a manner not reliant on any specific image format, display hardware or printer (hence the DVI format's name). DVI files are typically used as input to a second program (called a DVI driver) which translates DVI files to graphical data. For example, most TeX software packages include a program for previewing DVI files on a user's computer display; this program is a driver. Drivers are also used to convert DVI files to popular document formats (e.g. PostScript, PDF) and for printing. Wikipedia uses a PNG driver to generate graphics for mathematical formulae in articles. A file format is a particular way to encode information for storage in a computer file. ... The TeX logo The TeX mascot, by Duane Bibby TEX, written as TeX in plain text, is a typesetting system created by Donald Knuth. ... Movable metal type Typesetting involves the presentation of textual material in an aesthetic form on paper or some other medium. ... Donald Knuth at a reception for the Open Content Alliance. ... This page refers to the year 1979. ... Computer files can be divided into two broad categories: binary and text. ... See also Category:Graphics file formats Here is a summary of the most common graphics file formats: Some file formats, e. ... Nineteen inch (48 cm) CRT computer monitor A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. ... A computer printer is a computer peripheral device that produces a hard copy (permanent human-readable text and/or graphics, usually on paper) from data stored in a computer connected to it. ... PostScript (PS) is a page description language and programming language used primarily in the electronic and desktop publishing areas. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A PNG image with an 8-bit transparency layer (top), overlayed onto a chequered background (bottom). ...


DVI is not a document encryption format, and TeX markup may be at least partially reverse-engineered from DVI files, although this process is unlikely to produce high-level constructs identical to those present in the original markup, especially if the original markup used high-level TeX extensions (e.g. LaTeX). In cryptography, encryption is the process of obscuring information to make it unreadable without special knowledge. ... Reverse engineering (RE) is the process of taking something (a device, an electrical component, a software program, etc. ... The extraction of Latex from a tree; Latex is used in Rubber production Latex, as found in nature, is the milky sap of many plants that coagulates on exposure to air. ...


DVI differs from PostScript and PDF in that it does not support any form of font embedding. (Both PostScript and PDF formats can either embed their fonts inside the documents, or reference external ones.) For a DVI file to be printed or even properly previewed, the fonts it references must be already installed. Also, unlike PostScript, DVI is not a full, Turing-complete programming language, though it does use a limited sort of machine language. In computability theory a programming language or any other logical system is called Turing-complete if it has a computational power equivalent to a universal Turing machine. ...


Specification

The DVI format was designed to be compact and easily machine-readable. Toward this end, a DVI file is a sequence of commands which form "a machine-like language", in Knuth's words. Each command begins with an eight-bit opcode, followed by zero or more bytes of parameters. For example, an opcode from the group 0x00 through 0x7F (decimal 127), set_char_i, typesets a single character and moves the implicit cursor right by that character's width. In contrast, opcode 0xF7 (decimal 247), pre (the preamble, which must be the first opcode in the DVI file), takes at least fourteen bytes of parameters, plus an optional comment of up to 255 bytes. A system of codes directly understandable by a computers CPU is termed this CPUs native or machine language. ... Donald Knuth Donald Ervin Knuth (born January 10, 1938) is a renowned computer scientist and Professor Emeritus at Stanford University. ...


In a broader sense, a DVI file consists of a preamble, one or more pages, and a postamble. Six state variables are maintained as a tuple of signed, 32-bit integers: (h,v,w,x,y,z). h and v are the current horizontal and vertical offsets from the upper-left corner (increasing v moves down the page), w and x hold horizontal space values, y and z, vertical. These variables can be pushed or popped from the stack.


Fonts are loaded from TFM files. The fonts themselves are not embedded in the DVI file, only referenced. Each font, once loaded, is referenced by an internal index providing a compact format. A TeX font metric, or TFM, is a font metric format used by TeX. Unlike outline font formats such as TrueType, a TFM provides only the information necessary to typeset the font: each characters width, height and depth. ...


The DVI format also relies on the character encodings of the fonts it references, not on those of the system processing it. This means, for instance, that an EBCDIC-based system can process a DVI file that was generated by an ASCII-based system. A character encoding consists of a code that pairs a set of characters (representations of graphemes or grapheme-like units, such as might appear in an alphabet or syllabary for the communication of a natural language) with a set of something else, such as numbers or electrical pulses, in order... EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM... There are 95 printable ASCII characters, numbered 32 to 126. ...


References

  • DVIType.web, a DVI parser written in WEB, which contains the full DVI format specification when extracted with WEAVE.

For other uses, see web. ...

External link


  Results from FactBites:
 
DVI (file format) - Wikipedia, the free encyclopedia (572 words)
Unlike the TeX markup files used to generate them, DVI files are not intended to be human-readable; they consist of binary data describing the visual layout of a document in a manner not reliant on any specific image format, display hardware or printer (hence the DVI format's name).
DVI is not a document encryption format, and TeX markup may be at least partially reverse-engineered from DVI files, although this process is unlikely to produce high-level constructs identical to those present in the original markup, especially if the original markup used high-level TeX extensions (e.g.
Toward this end, a DVI file is a sequence of commands which form "a machine-like language", in Knuth's words.
Intel DVI: Summary from the Encyclopedia of Graphics File Formats (2465 words)
DVI originated in 1984 at the David Sarnoff Research Center in Princeton, New Jersey, which was the central research facility for RCA Corporation.
DVI is actually both the name of the Digital Video Interactive hardware system sold by Intel and the file format associated with that system.
If the streams within a DVI file are organized as groups, then the StreamGroupCount value indicates the number of groups; the StreamGroupSize value specifies the size of each group; the StreamGroupOffset value points to the location of the first group; and the StreamGroupVersion specifies the format of the group.
  More results at FactBites »

 
 

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