qccwavwaveletshapeadaptivedwt1d.3

spiht for linux this is used to decod and encode vedio i wich all enjoy

.TH QCCWAVWAVELETSHAPEADAPTIVEDWT1D 3 "QCCPACK" ""
.SH NAME
QccWAVWaveletShapeAdaptiveDWT1D, QccWAVWaveletInverseShapeAdaptiveDWT1D \- 
shape-adaptive discrete wavelet transform and inverse transform for a 1D signal
.SH SYNOPSIS
.B #include "libQccPack.h"
.sp
.BI "int QccWAVWaveletShapeAdaptiveDWT1D(QccVector " signal ", QccVector " mask ", int " signal_length ", int " num_scales ", const QccWAVWavelet *" wavelet );
.br
.BI "int QccWAVWaveletInverseShapeAdaptiveDWT1D(QccVector " signal ", QccVector " mask ", int " signal_length ", int " num_scales ", const QccWAVWavelet *" wavelet );
.SH DESCRIPTION
.B QccWAVWaveletShapeAdaptiveDWT1D()
performs a shape-adaptive discrete
wavelet transform (SA-DWT) of a one-dimensional signal.
.I num_scales
gives the number of scales, or levels, of the decomposition.
.BR QccWAVWaveletShapeAdaptiveDWT1D()
implements a dyadic decomposition of
.IR signal ;
that is, the lowpass subband is recursively decomposed into lowpass and
highpass bands for each level of decomposition.
The output of the SA-DWT is returned in
.IR signal ,
overwriting the original input signal.
The output subbands reside in 
.I signal
starting with the lowpass subband of the lowest (coarsest) level of
decomposition (i.e., the baseband) with subsequent highpass subbands
of increasing resolution following.
.LP
.I mask
indicates where the original input
.I signal
exists. That is, 
.I mask
indicates the intervals of support in the original input
.IR signal .
Where
.I mask
is less than or equal to
.BR QCCALPHA_TRANSPARENT ,
there is no signal, and where
.I mask
is greater than
.BR QCCALPHA_TRANSPARENT ,
the signal exists and is transformed
(see
.BR QccAlpha (3)).
Essentially this shape-adaptive transform is performed by identifying
contiguous non-transparent segments of the input signal, and transforming
these segments individually with a usual 1D DWT 
(via a call to
.BR QccWAVWaveletDWT1D (3))
with appropriate
extension at the ends of each segment.
Each segment is transformed so that the global subsampling scheme for
the signal is respected; that is, the starting index for each segment is
determined to be either odd or even based upon its location relative
to the start of
.IR signal ,
and this determines whether odd or even subsampling is used in the
DWT of the segment.
.LP
The transparency mask is transformed (with a Lazy wavelet transform)
alongside the signal so that, at completion of the transform,
.IR mask
indicates where valid coefficients, i.e., coefficients resulting from
non-transparent segments in the input signal,
reside in the output
.IR signal .
The transformed mask is returned in
.IR mask ,
overwriting the original input mask.
.LP
Currently, 
.BR QccWAVWaveletShapeAdaptiveDWT1D()
supports only biorthogonal wavelets. These may be
used with symmetric extension (lifting or filter-bank
implementations) or boundary-wavelet extension
(lifting implementations only).
.LP
Segments within
.I signal
may be of any length, odd or even.
In the case of odd segment length, either the lowpass or highpass
subband at the next coarser scale
will be one sample longer than
the other; which one is longer depends on whether the segment
starts with an even- or odd-indexed sample relative to the
start of
.IR signal .
A segment of length one, i.e., an isolated signal sample,
is somewhat of a degenerate case.
.BR QccWAVWaveletShapeAdaptiveDWT1D()
handles a length-1 segment as follows.
If the isolated  sample is even-indexed relative to the start of
.IR signal ,
then the sample value is multiplied by sqrt(2) and placed in the
lowpass band. If the isolated sample is odd-index, it is divided by
sqrt(2) and placed in the highpass band.
.LP
.B QccWAVWaveletInverseShapeAdaptiveDWT1D()
performs the inverse SA-DWT of
.IR signal
which is assumed to have been produced
by
.BR QccWAVWaveletShapeAdaptiveDWT1D() .
.IR mask
should be the corresponding Lazy-wavelet transformed mask
also produced by
.BR QccWAVWaveletShapeAdaptiveDWT1D() .
.I num_scales
gives the number of levels of decomposition that exist in
.IR signal .
.SH "RETURN VALUES"
These routines
return 0 on success and 1 on error.
.SH "NOTES"
SA-DWTs have been recently included in Version 2 of the MPEG-4
standard, wherein they are used for 
texture coding of arbitrarily shaped still objects.
Li and Li (see below) elaborate at length on the shape-adaptive DWT
used in MPEG-4, and also consider some variants not included
in the MPEG-4 standard.
.LP
The SA-DWT implemented in QccPack differs slightly
from the transform specified by MPEG-4.
The most significant difference is in the handling of isolated samples 
(i.e., segments with length one). In MPEG-4, isolated samples are always
multiplied by sqrt(2) and placed in the lowpass band regardless of the
parity of the index of the sample. Another difference
is that the QccPack SA-DWT
can handle boundary-wavelet extension in addition to symmetric extension
for lifting implementations of wavelets; MPEG-4 uses only symmetric extension.
Finally, Li and Li describe several SA-DWT variants that
are currently not implemented in QccPack, namely, SA-DWTs
using orthonormal wavelets or biorthogonal wavelets with even-length symmetric
filters.
.SH "SEE ALSO"
.BR QccWAVWaveletDWT1D (3),
.BR QccWAVWaveletInverseDWT1D (3),
.BR QccWAVWavelet (3),
.BR QccPackWAV (3),
.BR QccPack (3)
.LP
S. Li and W. Li, "Shape-Adaptive Discrete Wavelet Transforms for
Arbitrarily Shaped Visual Object Coding,"
.IR "IEEE Transactions on Circuits and Systems for Video Coding" ,
vol. 10, pp. 725-743, August 2000.
.LP
ISO/IEC 14496-2, "Information Technology -- Coding of audio-visual objects --
Part 2: Visual," 
.IR "MPEG-4 Standard" ,
Amendment 1, July 2000.
.SH AUTHOR
Copyright (C) 1997-2009  James E. Fowler
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