Lines Matching full:vorbis
4 \section{Introduction and Description} \label{vorbis:spec:intro}
8 This document provides a high level description of the Vorbis codec's
10 \xref{vorbis:spec:codec}.
12 understanding of the Vorbis decode process, which is
16 Vorbis is a general purpose perceptual audio CODEC intended to allow
22 without resampling to a lower rate. Vorbis is also intended for
30 Vorbis I is a forward-adaptive monolithic transform CODEC based on the
32 addition of a hybrid wavelet filterbank in Vorbis II to offer better
39 The Vorbis CODEC design assumes a complex, psychoacoustically-aware
40 encoder and simple, low-complexity decoder. Vorbis decode is
42 working memory as Vorbis has no static probability model; the vector
44 packed in their entirety into the Vorbis bitstream headers. In
50 Vorbis provides none of its own framing, synchronization or protection
56 audio stream. Vorbis is a free-form variable bit rate (VBR) codec and packets have no
64 Vorbis packets are thus intended to be used with a transport mechanism
68 examples in this document, we will assume that Vorbis is to be
70 requirement or fundamental assumption in the Vorbis design.
72 The specification for embedding Vorbis into
73 an Ogg transport stream is in \xref{vorbis:over:ogg}.
79 Vorbis' heritage is as a research CODEC and its current design
85 The single most controversial design decision in Vorbis (and the most
86 unusual for a Vorbis developer to keep in mind) is that the entire
96 Vorbis \emph{can} initiate decode at any arbitrary packet within a
101 Thus, Vorbis headers are both required for decode to begin and
104 recommended (and Xiph.Org's Vorbis encoder follows this suggestion).
112 Vorbis' suitable application space.
116 The Vorbis format is well-defined by its decode specification; any
118 reference Vorbis decoder described below may be considered a proper
119 Vorbis encoder. A decoder must faithfully and completely implement
121 a proper Vorbis decoder.
124 Although Vorbis decode is computationally simple, it may still run
148 (sample rate, channels), Vorbis version (always '0' in Vorbis I),
154 Each Vorbis frame is coded according to a master 'mode'. A bitstream
165 (always 0, the Vorbis window, in Vorbis I), transform type (always
166 type 0, the MDCT, in Vorbis I) and a mapping number. The mapping
188 Assume a Vorbis stream that contains six channels in the standard 5.1
201 Vorbis encodes a spectral 'floor' vector for each PCM channel. This
219 modern use. No known Vorbis encoder past Xiph.org's own beta 4 makes
248 The entropy coding in a Vorbis I codebook is provided by a standard
265 bitstream headers matching the stream to be decoded. Vorbis uses
268 belonging to the Vorbis stream. In Vorbis I, all packets after the
275 The identification header identifies the bitstream as Vorbis, Vorbis
282 encoding and proper use of the comment header is described in \xref{vorbis:spec:comment}.
302 \item inverse monolithic transform of audio spectrum vector, always an MDCT in Vorbis I
319 Vorbis I uses four packet types. The first three packet types mark each
320 of the three Vorbis headers described above. The fourth packet type
324 Following the three header packets, all packets in a Vorbis I stream
335 Vorbis allows an encoder to set up multiple, numbered packet 'modes',
336 as described earlier, all of which may be used in a given Vorbis
341 \paragraph{Window shape decode (long windows only)} \label{vorbis:spec:window}
343 Vorbis frames may be one of two PCM sample sizes specified during
344 codec setup. In Vorbis I, legal frame sizes are powers of two from 64
345 to 8192 samples. Aside from coupling, Vorbis handles channels as
348 Vorbis uses an overlapping transform, namely the MDCT, to blend one
374 window (short windows require no modification), Vorbis also codes two
383 can be found in \cite{Sporer/Brandenburg/Edler}. Vorbis windows
404 Vorbis codes residue vectors in groups by submap; the coding is done
413 A detailed discussion of stereo in the Vorbis codec can be found in
415 Vorbis CODEC}. Vorbis is not limited to only stereo coupling, but
419 Vorbis coupling applies to pairs of residue vectors at a time;
487 window (such as the Vorbis window) before the MDCT can be considered
