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Ogg
Vorbis Logo
File name extension . A filename extension is a suffix to the name of a Computer file applied to indicate the encoding convention ( File format) of its contents ogv, . oga, . ogx, . ogg
Internet media type video/ogg (unregistered), audio/ogg (unregistered), application/ogg
Magic number OggS
Developed by Xiph.Org Foundation
Type of format Container format
Container for Vorbis, Theora, Speex, FLAC, Dirac, and others. An Internet media type, originally called a MIME type after MIME and sometimes a Content-type after the name of a header in several protocols whose value The Internet Assigned Numbers Authority (IANA is the entity that oversees global IP address allocation, DNS root zone management, media types The Internet Assigned Numbers Authority (IANA is the entity that oversees global IP address allocation, DNS root zone management, media types A file format is a particular way to encode information for storage in a Computer file. The XiphOrg Foundation is a 501(c(3 Non-profit organization dedicated to producing free Multimedia formats and tools A container format is a computer file format that can contain various types of data compressed by means of standardized audio/video codecs. Vorbis is a free and open source, lossy audio Codec project headed by the Xiph Theora is an open and royalty-free Lossy Video compression technology being developed by the Xiph Speex is a Free software speech codec that may be used on VoIP applications and Podcasts Speex claims to be free of any patent restrictions Free Lossless Audio Codec ( FLAC) is a File format for lossless Audio data compression. Dirac is a prototype Algorithm for the encoding and decoding of raw video

Ogg is a free, open standard container format maintained by the Xiph.Org Foundation. A free file format is a File format whose full specification is freely available and for which there are no restrictions (e An open standard is a Standard that is publicly available and has various rights to use associated with it A container format is a computer file format that can contain various types of data compressed by means of standardized audio/video codecs. The XiphOrg Foundation is a 501(c(3 Non-profit organization dedicated to producing free Multimedia formats and tools The Ogg format is unrestricted by software patents and is designed to provide for efficient streaming and manipulation of high quality digital multimedia. Software patent does not have a universally accepted definition Streaming multimedia is Multimedia that is constantly received by and normally presented to an end-user while it is being delivered by a streaming provider (the Multimedia is media and content that utilizes a combination of different content forms.

The name ‘Ogg’ refers to the file format which can multiplex a number of separate independent free and open source codecs for audio, video, text (such as subtitles), and metadata. A file format is a particular way to encode information for storage in a Computer file. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Open source software (OSS began as a marketing campaign for Free software. A codec is a device or program capable of encoding and/or decoding a Digital Data stream or signal. Sound' is Vibration transmitted through a Solid, Liquid, or Gas; particularly sound means those vibrations composed of Frequencies Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images Subtitles are textual versions of the dialog in films and television programs usually displayed at the bottom of the screen Metadata ( meta data, or sometimes metainformation) is "data about data" of any sort in any media

In the Ogg multimedia framework, Theora provides a lossy video layer, while the music-oriented Vorbis codec most commonly acts as the audio layer. Theora is an open and royalty-free Lossy Video compression technology being developed by the Xiph A lossy compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original but is close enough to be useful Vorbis is a free and open source, lossy audio Codec project headed by the Xiph The human speech compression codec Speex, lossless audio compression codec FLAC, and OggPCM may also act as audio layers. Speex is a Free software speech codec that may be used on VoIP applications and Podcasts Speex claims to be free of any patent restrictions Lossless data compression is a class of Data compression Algorithms that allows the exact original data to be reconstructed from the compressed data Free Lossless Audio Codec ( FLAC) is a File format for lossless Audio data compression. OggPCM is a Data format which is used to encapsulate PCM audio data inside the Ogg container format.

The term ‘Ogg’ is commonly used to refer to audio file format Ogg Vorbis, that is, Vorbis-encoded audio in the Ogg container. An audio file format is a Container format for storing audio data on a Computer system Vorbis is a free and open source, lossy audio Codec project headed by the Xiph Previously, the . ogg file extension was used for any content distributed within Ogg, but as of 2007, the Xiph. Org Foundation requests that . ogg be used only for Vorbis due to backward compatibility concerns. The Xiph. Org Foundation decided to create a new set of file extensions and media types to describe different types of content such as . oga for audio only files, . ogv for video with or without sound (including Theora), and . ogx for applications. [1]

The current version of the Xiph. Org Foundation's reference implementation, released on 27 November 2005, is libogg 1. Events 1095 - Pope Urban II declares the First Crusade at the Council of Clermont Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. 1. 3. [2] Another version, libogg2, is also available from the Xiph. Org Foundation's SVN repositories. Both software libraries are free software, released under the new BSD license. In Computer science, a library is a collection of Subroutines used to develop Software. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified BSD licenses represent a family of Permissive free software licences.

Because the format is free, Ogg's various codecs have been incorporated into a number of different free and proprietary media players, both commercial and non-commercial, as well as portable media players and GPS receivers from different manufacturers. Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. Media player is a term typically used to describe Computer software for playing back Multimedia files Most software media players support an array of media A portable multimedia player ( PMP) sometimes referred to as a portable video player ( PVP) is a Consumer electronics device that is capable Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth

Contents

Naming

It is sometimes assumed that the name Ogg comes from the character of Nanny Ogg in Terry Pratchett's Discworld novels. Gytha Ogg (usually called Nanny Ogg) is a character from Terry Pratchett 's Discworld series Terence David John Pratchett, OBE (born 28 April 1948 is an English fantasy, Science fiction, and children's author. Discworld is a comedic Fantasy Book series by the British author Terry Pratchett, set on the Discworld, a flat However, it derives from ogging, jargon from the computer game Netrek which came to mean doing something forcefully, possibly without consideration of the drain on future resources. Ogging is term for a tactic developed for the online multiplayer game Netrek. For Wikipedia jargon see WikipediaGlossary. For hacker slang see Jargon File. Netrek is an Internet game for up to 16 players It is free to download and play written almost entirely in Open source software, is Cross platform At its inception, the Ogg project was thought to be somewhat ambitious given the power of the PC hardware of the time. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. [3][4]

File format

The Ogg bitstream format, spearheaded by the Xiph. A bitstream format is the format of the data found in some stream of bits used in a digital communication or storage application Org Foundation, has been created as the framework of a larger initiative aimed at developing a set of components for the coding and decoding of multimedia content which are available free of charge and are freely re-implementable in software.

The format consists of chunks of data each called an Ogg Page. An Ogg page is a variable sized unit of data within an Ogg bitstream Each page begins with the "OggS" string to identify the file as Ogg format.

A serial number and page number in the page header identifies each page as part of a series of pages making up a bitstream. A bitstream or bit stream is a Time series of Bits A Bytestream is a series of Bytes typically of 8 bits each and can be Multiple bitstreams may be multiplexed in the file where pages from each bitstream are ordered by the seek time of the contained data. For multiplexing in electronics and signal processing see Multiplexer. Bitstreams may also be appended to existing files, a process known as chaining, to cause the bitstreams to be decoded in sequence.

A BSD-licensed library, called libogg, is available to encode and decode data from Ogg streams. BSD licenses represent a family of Permissive free software licences. Independent Ogg implementations are used in several projects such as RealPlayer and a set of DirectShow filters. RealPlayer (briefly known also as RealOne Player) is a proprietary Cross-platform media player by RealNetworks that plays a number DirectShow (sometimes abbreviated as DS or DShow) codename Quartz, is a Multimedia framework and API produced by Microsoft

Page structure

The following is the field layout of an Ogg page header:

The field layout of an Ogg page header
Capture pattern — 32 bits
The capture pattern or sync code is a magic number used to ensure synchronisation when parsing Ogg files. Every page starts with the four byte sequence 'OggS'. This assists in resynchronising a parser in cases where data has been lost or is corrupted, and is a sanity check before commencing parsing the page structure.
Version — 8 bits
This field indicates the version of the Ogg bitstream format, to allow for future expansion. It is currently mandated to be 0.
Header type — 8 bits
This is an 8 bit field of flags, which indicates the type of page which follows. The rightmost or least significant bit is considered bit 0, with value 0x01, the next least significant digit is bit 1, with value 0x02. The third is bit 2, with value 0x04, and so on.
Bit Value Flag Page type
0 0x01 Continuation The first packet on this page is a continuation of the previous packet in the logical bitstream.
1 0x02 BOS Beginning Of Stream. This page is the first page in the logical bitstream. The BOS flag must be set on the first page of every logical bitstream, and must not be set on any other page.
2 0x04 EOS End Of Stream. This page is the last page in the logical bitstream. The EOS flag must be set on the final page of every logical bitstream, and must not be set on any other page.
Granule position — 64 bits
A granule position is the time marker in Ogg files. It is an abstract value, whose meaning is determined by the codec. It may for example be a count of the number of samples, the number of frames or a more complex scheme.
Bitstream serial number — 32 bits
This field is a serial number which identifies a page as belonging to a particular logical bitstream. Each logical bitstream in a file has a unique value, and this field allows implementations to deliver the pages to the appropriate decoder. In a typical vorbis+theora file, one stream will be the audio (vorbis), and the other will be the video (theora)
Page sequence number — 32 bits
This field is a monotonically increasing field for each logical bitstream. The first page is 0, the second 1, etc. This allows implementations to detect when data has been lost.
Checksum — 32 bits
This field provides a checksum of the data in the entire page, performed with the checksum field set to 0. This allows verification that the data has not been corrupted since it was created. Pages which fail the checksum should be discarded.
Page segments — 8 bits
This field indicates the number of segments that exist in this page. It also indicates how many bytes are in the segment table which follows this field. There can be a maximum of 255 segments in any one page.
Segment table
The segment table is an 8 bit vector of values indicating the length of each segment within the page body. The number of segments is determined from the preceding Page Segments field. Each segment is between 0 and 255 bytes in length.

The segments provide a way to group segments into packets, which are meaningful units of data for the decoder. When the segments length is indicated to be 255, this indicates that the following segment is to be concatenated to this one and is part of the same packet. When the segments length is 0-254, this indicates that this segment is the final segment in this packet. Where a packets length is a multiple of 255, the final segment will be of length 0.

Where the final packet continues on the next page, the final segment value will be 255, and the continuation flag will be set on the following page to indicate that the start of the new page is a continuation of last page.

Metadata

Currently, there is no official standard for including metadata in Ogg containers. Implementation is still a long way off as of Quarter 3, 2007. The Xiph. Org Foundation are currently welcoming suggestions and feedback. Suggested metadata implementation methods include the following: [5]

Metadata must currently be included in the codec. A codec is a device or program capable of encoding and/or decoding a Digital Data stream or signal. There is fairly good software support for Vorbis metadata—often referred to as comments. But software support for Theora and FLAC comments in Ogg containers is very limited.

History

The “Play Ogg” web button
The “Play Ogg” web button

In May 2003, two Internet RFCs were published relating to the format. Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. In Computer network Engineering, a Request for Comments (RFC is a Memorandum published by the Internet Engineering Task Force (IETF describing The Ogg bitstream was defined in RFC 3533 (which is classified as 'informative') and its Internet content type (application/ogg) in RFC 3534 (which is, as of 2006, a proposed standard protocol). Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar.

Although Ogg hasn't reached anywhere near the ubiquity of the MPEG standards [6] (e. The Moving Picture Experts Group, commonly referred to as simply MPEG, is a Working group of ISO / IEC charged with the development of video and g. : MP3 / MP4), as of 2006, it is commonly used to encode free content (such as free music, multimedia on Wikimedia projects and Creative Commons files) and has started to be supported by a significant minority of digital audio players. MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a Digital audio encoding format using a form of Lossy data compression MPEG-4 Part 14, formally ISO / IEC 14496-142003, is a Multimedia Container format standard specified as a part of MPEG-4 Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. _____ __ / ___/ / /_ ____ ____ \__ \ / __/ / __ \ / __ \ ___/ / / /_ The Wikimedia Foundation Inc is a Non-profit charitable organization headquartered in San Francisco, California, United States, Creative Commons (CC is a Non-profit organization devoted to expanding the range of creative works available for others to build upon legally and to share A digital audio player, more commonly referred to as an MP3 player, is a Consumer electronics device that stores organizes and plays audio files Some Also supporting the Ogg format have been many popular video game engines, including Doom 3, Unreal Tournament 2004, Myst IV: Revelation, Serious Sam: The Second Encounter, Lineage 2 and the Grand Theft Auto engines. Doom 3 is a Science fiction Survival horror Video game developed by Id Software and published by Activision. Unreal Tournament 2004, also known as UT2K4 and UT2004, is a futuristic First-person shooter computer game Myst IV Revelation is the fourth installment in the Myst Computer game series developed and published by Ubisoft. Serious Sam is the title of a series of First-person shooters created by the Croatian company Croteam. Lineage II The Chaotic Throne (리니지 2 is a Fantasy Massive multiplayer online role-playing game ( MMORPG) for the PC and a The more popular Vorbis codec has built-in support on many software players, and extensions are available for nearly all the rest. Other codecs are less well supported, although extensions are often available.

On May 16, 2007, the Free Software Foundation started a campaign to increase the use of Vorbis “as an ethically, legally and technically superior audio alternative to the proprietary MP3 format. The Free Software Foundation ( FSF) is a Non-profit corporation founded by Richard Stallman on 4 October 1985 to support the Free software movement ”[7] People are also encouraged to support the campaign by adding a web button to their website or blog. A website (alternatively web site or Web site, a back-construction from the Proper noun World Wide Web) is a collection of Web pages A blog (a contraction of the term " Web log " is a Web site, usually maintained by an individual with regular entries of commentary descriptions of For those who don't want to download and use FSF's suggested Ogg player (VLC), the Xiph.Org Foundation has an official codec[8] for QuickTime-based applications in Windows and Mac OS X, such as iTunes players and iMovie applications; and Windows users can install a Windows Media Player Ogg codec[9]. The XiphOrg Foundation is a 501(c(3 Non-profit organization dedicated to producing free Multimedia formats and tools QuickTime is a Multimedia framework developed by Apple Inc, capable of handling various formats of Digital video, Media clips sound text Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently iTunes is a proprietary digital media player application introduced by Apple Inc iMovie is a Video editing software application which allows Mac users to edit their own home movies Windows Media Player ( WMP) is a digital media player and media library application developed by Microsoft that is used for playing

Ogg codecs

Ogg is only a container format. The actual audio or video encoded by a codec will be stored inside an Ogg container. Ogg containers may contain streams encoded with multiple codecs, for example, a video file with sound contains data encoded by both an audio codec and a video codec.

Being a Container format, Ogg can embed audio and video in various formats (such as MPEG-4, Dirac, MP3 and others) but Ogg was intended and usually is used with the following free codecs:

See also

References

  1. ^ MIME Types and File Extensions. For processes which reduce the amount of time it takes to listen to and understand a recording see Time-compressed speech. This table compares features of container formats. Note that DirectShow filters allow playing on any DirectShow-based player including Windows Media Player. LRC is a Computer file format that synchronizes song Lyrics with an audio file such as MP3, Vorbis or MIDI. XiphWiki (2007-09-07). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1251 BC - A Solar eclipse on this date might mark the birth of legendary Heracles at Thebes Greece. Retrieved on 2007-09-10. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 506 - The Bishops of Visigothic Gaul meet in the Council of Agde.
  2. ^ [Vorbis-dev] libogg 1.1.3 and libvorbis 1.1.2 releases
  3. ^ Xiph.org: naming. Xiph. org Foundation (2006-01-07). Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1325 - Alfonso IV becomes King of Portugal. 1558 - France takes Calais, the last continental Retrieved on 2008-02-16. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1249 - Andrew of Longjumeau is dispatched by Louis IX of France as his ambassador to meet with the Khan of the Mongols  “At the time Ogg was starting out, most personal computers were i386s and the i486 was new. I remember thinking about the algorithms I was considering, "Woah, that's heavyweight. People are going to need a 486 to run that. . . " While the software ogged the music, there wasn't much processor left for anything else. ”
  4. ^ Medo (2005-12-20). Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Events 69 - Vespasian, formerly a general under Nero, enters Rome to claim the title of Emperor. Ogg Vorbis - Better Than Mp3?. BBC. Retrieved on 2007-06-24. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 972 - Battle of Cedynia, the first documented victory of Polish forces takes place
  5. ^ Ogg Metadata. Xiph Wiki (2005-12-20). Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Events 69 - Vespasian, formerly a general under Nero, enters Rome to claim the title of Emperor. Retrieved on 2007-08-31. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1056 - Byzantine Empress Theodora becomes ill dying suddenly a few days later without children to succeed the Throne
  6. ^ MP3's Loss, Open Source's Gain
  7. ^ 'Play Ogg': FSF launches free audio format campaign
  8. ^ Xiph.Org Foundation: Ogg QuickTime Components for iTunes and iMovie (Windows and Mac OS X)
  9. ^ Windows Media Player Directshow Filters for Vorbis, Speex, Theora and FLAC

External links

The Jargon File is a Glossary of hacker Slang. The original Jargon File was a collection of hacker slang from technical cultures such as the MIT AI DOS, short for "Disk Operating System" is a shorthand term for several closely related Operating systems that dominated the IBM PC compatible market HX DOS-Extender is a free DOS extender with built-in Win32 PE file format support

Dictionary

Ogg

-proper noun

  1. An open, bitstream container file format for audio, video, and other multimedia content.
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