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diff --git a/doc/vorbis.html b/doc/vorbis.html deleted file mode 100644 index 27e3a5b0..00000000 --- a/doc/vorbis.html +++ /dev/null @@ -1,196 +0,0 @@ -<HTML><HEAD><TITLE>xiph.org: Ogg Vorbis documentation</TITLE> -<BODY bgcolor="#ffffff" text="#202020" link="#006666" vlink="#000000"> -<nobr><img src="white-ogg.png"><img src="vorbisword2.png"></nobr><p> - - -<h1><font color=#000070> -Ogg Vorbis encoding format documentation -</font></h1> - -<em>Last update to this document: July 15, 1999</em><br> -<em>Last update to Vorbis documentation: July 21, 1999</em><p> - -<table><tr><td> -<img src=wait.png> -</td><td valign=center> -As of writing, not all the below document -links are live. They will be populated as we complete the -documents. -</td></tr></table> - -<p> -<h2>Documents</h2> -<ul> -<li><a href="packet.html">Vorbis packet structure</a> -<li><a href="envelope.html">Temporal envelope shaping and blocksize</a> -<li><a href="mdct.html">Time domain segmentation and MDCT transform</a> -<li><a href="resolution.html">The resolution floor</a> -<li><a href="residuals.html">MDCT-domain fine structure</a><p> - -<li><a href="probmodel.html">The Vorbis probability model</a> - -<li><a href="bitpack.html">The Vorbis bitpacker</a><p> - -<li><a href="oggstream.html">Ogg bitstream overview</a> -<li><a href="framing.html">Ogg logical bitstream and framing spec</a> -<li><a href="vorbis-stream.html">Vorbis packet->Ogg bitstream - mapping</a><p> - -<li><a href="programming.html">Programming with libvorbis</a><p> -</ul> - -<h2>Description</h2> -Ogg Vorbis is a general purpose compressed audio format -for high quality (44.1-48.0kHz, 16+ bit, polyphonic) audio and music -at moderate fixed and variable bitrates (40-80 kb/s/channel). This -places Vorbis in the same class as audio representations including -MPEG-1 audio layer 3, MPEG-4 audio (AAC and TwinVQ), and PAC.<p> - -Vorbis is the first of a planned family of Ogg multimedia coding -formats being developed as part of Xiphophorus's Ogg multimedia -project. See <a href="http://www.xiph.org/">http://www.xiph.org/</a> -for more information. - -<h2>Vorbis technical documents</h2> - -A Vorbis encoder takes in overlapping (but contiguous) short-time -segments of audio data. The encoder analyzes the content of the audio -to determine an optimal compact representation; this phase of encoding -is known as <em>analysis</em>. For each short-time block of sound, -the encoder then packs an efficient representation of the signal, as -determined by analysis, into a raw packet much smaller than the size -required by the original signal; this phase is <em>coding</em>. -Lastly, in a streaming environment, the raw packets are then -structured into a continuous stream of octets; this last phase is -<em>streaming</em>. Note that the stream of octets is referred to both -as a 'byte-' and 'bit-'stream; the latter usage is acceptible as the -stream of octets is a physical representation of a true logical -bit-by-bit stream.<p> - -A Vorbis decoder performs a mirror image process of extracting the -original sequence of raw packets from an Ogg stream (<em>stream -decomposition</em>), reconstructing the signal representation from the -raw data in the packet (<em>decoding</em>) and them reconstituting an -audio signal from the decoded representation (<em>synthesis</em>).<p> - -The <a href="programming.html">Programming with libvorbis</a> -documents discuss use of the reference Vorbis codec library -(libvorbis) produced by Xiphophorus.<p> - -The data representations and algorithms necessary at each step to -encode and decode Ogg Vorbis bitstreams are described by the below -documents in sufficient detail to construct a complete Vorbis codec. -Note that at the time of writing, Vorbis is still in a 'Request For -Comments' stage of development; despite being in advanced stages of -development, input from the multimedia community is welcome.<p> - -<h3>Vorbis analysis and synthesis</h3> - -Analysis begins by seperating an input audio stream into individual, -overlapping short-time segments of audio data. These segments are -then transformed into an alternate representation, seeking to -represent the original signal in a more efficient form that codes into -a smaller number of bytes. The analysis and transformation stage is -the most complex element of producing a Vorbis bitstream.<p> - -The corresponding synthesis step in the decoder is simpler; there is -no analysis to perform, merely a mechanical, deterministic -reconstruction of the original audio data from the transform-domain -representation.<p> - -<ul> -<li><a href="packet.html">Vorbis packet structure</a>: Describes the basic analysis components necessary to produce Vorbis packets and the structure of the packet itself. -<li><a href="envelope.html">Temporal envelope shaping and blocksize</a>: Use of temporal envelope shaping and variable blocksize to minimize time-domain energy leakage during wide dynamic range and spectral energy swings. Also discusses time-related principles of psychoacoustics. -<li><a href="mdct.html">Time domain segmentation and MDCT transform</a>: Division of time domain data into individual overlapped, windowed short-time vectors and transformation using the MDCT -<li><a href="resolution.html">The resolution floor</a>: Use of frequency doamin psychoacoustics, and the MDCT-domain noise, masking and resolution floors -<li><a href="residuals.html">MDCT-domain fine structure</a>: Production, quantization and massaging of MDCT-spectrum fine structure -</ul> - -<h3>Vorbis coding and decoding</h3> - -Coding and decoding converts the transform-domain representation of -the original audio produced by analysis to and from a bitwise packed -raw data packet. Coding and decoding consist of two logically -orthogonal concepts, <em>back-end coding</em> and <em>bitpacking</em>.<p> - -<em>Back-end coding</em> uses a probability model to represent the raw numbers -of the audio representation in as few physical bits as possible; -familiar examples of back-end coding include Huffman coding and Vector -Quantization.<p> - -<em>Bitpacking</em> arranges the variable sized words of the back-end -coding into a vector of octets without wasting space. The octets -produced by coding a single short-time audio segment is one raw Vorbis -packet.<p> - -<ul> - -<li><a href="probmodel.html">The Vorbis probability model</a> - -<li><a href="bitpack.html">The Vorbis bitpacker</a>: Arrangement of -variable bit-length words into an octet-aligned packet. - -</ul> - -<h3>Vorbis streaming and stream decomposition</h3> - -Vorbis packets contain the raw, bitwise-compressed representation of a -snippet of audio. These packets contain no structure and cannot be -strung together directly into a stream; for streamed transmission and -storage, Vorbis packets are encoded into an Ogg bitstream.<p> - -<ul> - -<li><a href="oggstream.html">Ogg bitstream overview</a>: High-level -description of Ogg logical bitstreams, how logical bitstreams -(of mixed media types) can be combined into physical bitstreams, and -restrictions on logical-to-physical mapping. Note that this document is -not specific only to Ogg Vorbis. - -<li><a href="framing.html">Ogg logical bitstream and framing -spec</a>: Low level, complete specification of Ogg logical -bitstream pages. Note that this document is not specific only to Ogg -Vorbis. - -<li><a href="vorbis-stream.html">Vorbis bitstream mapping</a>: -Specifically describes mapping Vorbis data into an -Ogg physical bitstream. - -</ul> - - -<hr> -<a href="http://www.xiph.org/"> -<img src="white-xifish.png" align=left border=0> -</a> -<font size=-2 color=#505050> - -Ogg is a <a href="http://www.xiph.org">Xiphophorus</a> effort to -protect essential tenets of Internet multimedia from corporate -hostage-taking; Open Source is the net's greatest tool to keep -everyone honest. See <a href="http://www.xiph.org/about.html">About -Xiphophorus</a> for details. -<p> - -Ogg Vorbis is the first Ogg audio CODEC. Anyone may -freely use and distribute the Ogg and Vorbis specification, -whether in a private, public or corporate capacity. However, -Xiphophorus and the Ogg project (xiph.org) reserve the right to set -the Ogg/Vorbis specification and certify specification compliance.<p> - -Xiphophorus's Vorbis software CODEC implementation is distributed -under the Lesser/Library GNU Public License. This does not restrict -third parties from distributing independent implementations of Vorbis -software under other licenses.<p> - -OggSquish, Vorbis, Xiphophorus and their logos are trademarks (tm) of -<a href="http://www.xiph.org/">Xiphophorus</a>. These pages are -copyright (C) 1994-2000 Xiphophorus. All rights reserved.<p> - -</body> - - - - - - |