<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Tools for Real-time Spectral Processing (pvs opcodes)</title>
<link rel="stylesheet" type="text/css" href="csound.css" />
<link rel="stylesheet" type="text/css" href="syntax-highlighting.css" />
<meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" />
<link rel="home" href="index.html" title="The Canonical Csound Reference Manual" />
<link rel="up" href="SpectralTop.html" title="Spectral Processing" />
<link rel="prev" href="SpectralNonstand.html" title="Non-standard Spectral Processing" />
<link rel="next" href="SpectralATS.html" title="ATS Spectral Processing" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">Tools for Real-time Spectral Processing (pvs opcodes)</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="SpectralNonstand.html">Prev</a> </td>
<th width="60%" align="center">Spectral Processing</th>
<td width="20%" align="right"> <a accesskey="n" href="SpectralATS.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="SpectralRealTime"></a>Tools for Real-time Spectral Processing (pvs opcodes)</h2>
</div>
</div>
</div>
<p>
With these opcodes, two new core facilities are added to Csound. They offer improved audio quality, and fast performance, enabling high-quality analysis and resynthesis (together with transformations) to be applied in real-time to live signals. The original Csound phase vocoder remains unaltered; the new opcodes use an entirely separate set of functions based on <span class="quote">“<span class="quote">pvoc.c</span>”</span> in the CARL distribution, written by Mark Dolson.
</p>
<p>
The Csound <a class="link" href="dnoise.html" title="dnoise"><em class="citetitle">dnoise</em></a> and <a class="link" href="srconv.html" title="srconv"><em class="citetitle">srconv</em></a> utilities (also by Dolson, from CARL) also use this pvoc engine. CARL pvoc is also the basis for the phase vocoder included in the Composer's Desktop Project. A few small but important modifications have been made to the original CARL code to support real-time streaming.
</p>
<p>
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>Support for the new PVOC-EX analysis file format. This is a fully portable (cross-platform) open file format, supporting three analysis formats, and multi-channel signals. Currently only the standard amplitude+frequency format has been implemented in the opcodes, but the file format itself supports amplitude+phase and complex (real-imaginary) formats. In addition to the new opcodes, the original Csound pvoc opcodes have been extended (and thereby with enhanced audio quality in some cases) to read PVOC-EX files as well as the original (non-portable) format.</p>
<p>Full details of the structure of a PVOC-EX file are
available via the website: <a class="ulink" href="http://www.cs.bath.ac.uk/~jpff/NOS-DREAM/researchdev/pvocex/pvocex.html" target="_top"><em class="citetitle">http://www.cs.bath.ac.uk/~jpff/NOS-DREAM/researchdev/pvocex/pvocex.html</em></a>. This
site also gives details of the freely available console programs
pvocex and pvocex2 which can be used to create PVOC-EX files in
all supported formats.
</p>
</li>
<li class="listitem">
<p>
A new frequency-domain signal type, fully
streamable, with <span class="emphasis"><em>f</em></span> as the leading character.
In this document it is conveniently referred to as an
<span class="emphasis"><em>fsig</em></span>. Primary support for fsigs is provided
by the opcodes pvsanal and pvsynth, which perform conventional
phase vocoder overlap-add analysis and resynthesis, independently
of the orchestra control-rate. The only requirement is that the
control-rate kr be higher than or equal to the analysis rate,
whch can be expressed by the requirement that ksmps <=
overlap, where overlap is the distance in samples between
analysis frames, as specified for pvsanal. As overlap is
typically at least 128, and more usually 256, this is not an
onerous restriction in practice. The opcode pvsinfo can be used
at init time to acquire the properties of an fsig.</p>
<p>The fsig enables the nominal separation between the
analysis and resynthesis stages of the phase vocoder to be
exposed to the Csound programmer, so that not only can
alternatives be employed for either or both of these stages (not
only oscillator-bank resynthesis, but also the generation of
synthetic fsig streams), but opcodes, operating on the fsig
stream, can themselves become more elemental. Thus the fsig
enables the creation of a true streaming plugin framework for
frequency domain signals. With the old pvoc opcodes, each opcode
is required to act as a resynthesiser, so that facilities such
as pitch scaling are duplicated in each opcode; and in many
cases the opcodes are parameter-rich. The separation of analysis
and synthesis stages by means of the fsig encourages the
development of a wide range of simple building-block opcodes
implementing one or two functions, with which more elaborate
processes can be constructed.
</p>
</li>
</ol>
</div>
<p>
</p>
<p>
This is very much a preliminary and experimental release, and it is possible that the precise definition of the opcodes may change, in response to user feedback. Also, clearly, many new possibilities for opcodes are opened up; these factors may also have a retrospective influence on the opcodes presented here.
</p>
<p>
Note that some opcode parameters currently have restricted or
missing implementation. This is at least in part in order to keep
the opcodes simple at this stage, and also because they highlight
important design issues on which no decision has yet been made,
and on which opinions from users are sought.
</p>
<p>
One important point about the new signal type is that because the
analysis rate is typically much lower than kr, new analysis frames
are not available on each k-cycle. Internally, the opcodes track
ksmps, and also maintain a frame counter, so that frames are read
and written at the correct times; this process is generally
transparent to the user. However, it means that k-rate signals
only act on an fsig at the analysis rate, not at each k-cycle.
The opocde pvsftw returns a k-rate flag that is set when new fsig
data is valid.
</p>
<p>
Because of the nature of the overlap-add system, the use of these
opcodes incurs a small but significant delay, or latency,
determined by the window size (max(ifftsize,iwinsize)). This is
typically around 23msecs. In this first release, the delay is
slightly in excess of the theoretical minimum, and it is hoped
that it can be reduced, as the opcodes are further optimized for
real-time streaming.
</p>
<p>
The opcodes for real-time spectral processing are
<a class="link" href="pvsadsyn.html" title="pvsadsyn"><em class="citetitle">pvsadsyn</em></a>,
<a class="link" href="pvsanal.html" title="pvsanal"><em class="citetitle">pvsanal</em></a>,
<a class="link" href="pvscross.html" title="pvscross"><em class="citetitle">pvscross</em></a>,
<a class="link" href="pvsfread.html" title="pvsfread"><em class="citetitle">pvsfread</em></a>,
<a class="link" href="pvsftr.html" title="pvsftr"><em class="citetitle">pvsftr</em></a>,
<a class="link" href="pvsftw.html" title="pvsftw"><em class="citetitle">pvsftw</em></a>,
<a class="link" href="pvsinfo.html" title="pvsinfo"><em class="citetitle">pvsinfo</em></a>,
<a class="link" href="pvsmaska.html" title="pvsmaska"><em class="citetitle">pvsmaska</em></a>, and
<a class="link" href="pvsynth.html" title="pvsynth"><em class="citetitle">pvsynth</em></a>.
</p>
<p>
In addition there are a number of opcodes available as plugins in
Csound5,and in the core for Csound6. These are
<a class="link" href="pvstanal.html" title="pvstanal"><em class="citetitle">pvstanal</em></a>,
<a class="link" href="pvsdiskin.html" title="pvsdiskin"><em class="citetitle">pvsdiskin</em></a>,
<a class="link" href="pvscent.html" title="pvscent"><em class="citetitle">pvscent</em></a>,
<a class="link" href="pvsdemix.html" title="pvsdemix"><em class="citetitle">pvsdemix</em></a>,
<a class="link" href="pvsfreeze.html" title="pvsfreeze"><em class="citetitle">pvsfreeze</em></a>,
<a class="link" href="pvsbuffer.html" title="pvsbuffer"><em class="citetitle">pvsbuffer</em></a>,
<a class="link" href="pvsbufread.html" title="pvsbufread"><em class="citetitle">pvsbufread</em></a>,
<a class="link" href="pvsbufread.html" title="pvsbufread"><em class="citetitle">pvsbufread2</em></a>,
<a class="link" href="pvscale.html" title="pvscale"><em class="citetitle">pvscale</em></a>,
<a class="link" href="pvshift.html" title="pvshift"><em class="citetitle">pvshift</em></a>,
<a class="link" href="pvsifd.html" title="pvsifd"><em class="citetitle">pvsifd</em></a>,
<a class="link" href="pvsinit.html" title="pvsinit"><em class="citetitle">pvsinit</em></a>,
<a class="link" href="pvsin.html" title="pvsin"><em class="citetitle">pvsin</em></a>,
<a class="link" href="pvsout.html" title="pvsout"><em class="citetitle">pvsout</em></a>,
<a class="link" href="pvsosc.html" title="pvsosc"><em class="citetitle">pvsosc</em></a>,
<a class="link" href="pvsbin.html" title="pvsbin"><em class="citetitle">pvsbin</em></a>,
<a class="link" href="pvsdisp.html" title="pvsdisp"><em class="citetitle">pvsdisp</em></a>,
<a class="link" href="pvsfwrite.html" title="pvsfwrite"><em class="citetitle">pvsfwrite</em></a>,
<a class="link" href="pvslock.html" title="pvslock"><em class="citetitle">pvslock</em></a>,
<a class="link" href="pvsmix.html" title="pvsmix"><em class="citetitle">pvsmix</em></a>,
<a class="link" href="pvsmooth.html" title="pvsmooth"><em class="citetitle">pvsmooth</em></a>,
<a class="link" href="pvsfilter.html" title="pvsfilter"><em class="citetitle">pvsfilter</em></a>,
<a class="link" href="pvsblur.html" title="pvsblur"><em class="citetitle">pvsblur</em></a>,
<a class="link" href="pvstencil.html" title="pvstencil"><em class="citetitle">pvstencil</em></a>,
<a class="link" href="pvsarp.html" title="pvsarp"><em class="citetitle">pvsarp</em></a>,
<a class="link" href="pvsvoc.html" title="pvsvoc"><em class="citetitle">pvsvoc</em></a>,
<a class="link" href="pvsmorph.html" title="pvsmorph"><em class="citetitle">pvsmorph</em></a>,
<a class="link" href="pvsbandp.html" title="pvsbandp"><em class="citetitle">pvsbandp</em></a>,
<a class="link" href="pvsbandr.html" title="pvsbandr"><em class="citetitle">pvsbandr</em></a>,
<a class="link" href="pvswarp.html" title="pvswarp"><em class="citetitle">pvswarp</em></a>,
<a class="link" href="pvsgain.html" title="pvsgain"><em class="citetitle">pvsgain</em></a>,
<a class="link" href="pvs2tab.html" title="pvs2tab"><em class="citetitle">pvs2tab</em></a>,
<a class="link" href="tab2pvs.html" title="tab2pvs"><em class="citetitle">tab2pvs</em></a>.
</p>
<p>
A number of opcodes are designed to generate and process streaming
partials tracks data. these are
<a class="link" href="partials.html" title="partials"><em class="citetitle">partials</em></a>,
<a class="link" href="trcross.html" title="trcross"><em class="citetitle">trcross</em></a>,
<a class="link" href="trfilter.html" title="trfilter"><em class="citetitle">trfilter</em></a>,
<a class="link" href="trsplit.html" title="trsplit"><em class="citetitle">trsplit</em></a>,
<a class="link" href="trmix.html" title="trmix"><em class="citetitle">trmix</em></a>,
<a class="link" href="trscale.html" title="trscale"><em class="citetitle">trscale</em></a>,
<a class="link" href="trshift.html" title="trshift"><em class="citetitle">trshift</em></a>,
<a class="link" href="trlowest.html" title="trlowest"><em class="citetitle">trlowest</em></a>,
<a class="link" href="trhighest.html" title="trhighest"><em class="citetitle">trhighest</em></a>
<a class="link" href="tradsyn.html" title="tradsyn"><em class="citetitle">tradsyn</em></a>,
<a class="link" href="sinsyn.html" title="sinsyn"><em class="citetitle">sinsyn</em></a>,
<a class="link" href="resyn.html" title="resyn"><em class="citetitle">resyn</em></a>,
<a class="link" href="binit.html" title="binit"><em class="citetitle">binit</em></a>
</p>
<p>
See the <a class="link" href="ControlStacks.html" title="Stacks"><em class="citetitle">Stacks</em> section </a> for information on the stack opcodes which can stack f-signals.
</p>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="SpectralNonstand.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="SpectralTop.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="SpectralATS.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Non-standard Spectral Processing </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> ATS Spectral Processing</td>
</tr>
</table>
</div>
</body>
</html>
distrib
>
Mageia
>
7
>
armv7hl
>
media
>
core-release
>
by-pkgid
>
5fcfcb7517038d1f44ab4e478e6e61fa
>
files
>
335
