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<div class="refentry" title="pvsbufread">
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<h2>
<span class="refentrytitle">pvsbufread</span>
</h2>
<p>pvsbufread —
This opcode reads a circular buffer of f-signals (streaming PV signals).
</p>
</div>
<div class="refsect1" title="Description">
<a id="id3129623"></a>
<h2>Description</h2>
<p>
This opcode sets up and writes to a circular buffer of length ilen (secs),
giving a handle for the buffer and a time pointer, which holds the
current write position (also in seconds). It can be used with one or
more pvsbufread opcodes. Writing is circular, wrapping around at the
end of the buffer.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="id3130345"></a>
<h2>Syntax</h2>
<pre class="synopsis">fsig <span class="command"><strong>pvsbufread</strong></span> ktime, khandle[, ilo, ihi] </pre>
</div>
<div class="refsect1" title="Initialisation">
<a id="id3130363"></a>
<h2>Initialisation</h2>
<p>
<span class="emphasis"><em>ilo, ihi</em></span> -- set the lowest and highest freqs to be read from the buffer (defaults to 0, Nyquist).
</p>
<p>
<span class="emphasis"><em>fsig</em></span> -- output pv stream
</p>
<p>
<span class="emphasis"><em>ktime</em></span> -- time position of reading pointer (in secs).
</p>
<p>
<span class="emphasis"><em>khandle</em></span> -- handle identifying the buffer to be read. When using k-rate
handles, it is important to initialise the k-rate variable to a given existing handle. When changing
buffers, fsig buffers need to be compatible (same fsig format).
</p>
<p>
<span class="emphasis"><em>pvsbufread</em></span> reads f-signals from a buffer created by
</p>
<p>
With this opcode and <a class="link" href="pvsbuffer.html" title="pvsbuffer"><em class="citetitle">pvsbuffer</em></a>, it is possible to, among other things:
</p>
<table border="0" summary="Simple list" class="simplelist"></table>
<p>
</p>
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<th align="left">Note</th>
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<td align="left" valign="top">
<p>It is important that the handle value passed to <span class="emphasis"><em>pvsbufread</em></span> is valid and was created by <a class="link" href="pvsbuffer.html" title="pvsbuffer"><em class="citetitle">pvsbuffer</em></a>. Csound will crash with invalid handles.
</p>
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<div class="refsect1" title="Examples">
<a id="id3130486"></a>
<h2>Examples</h2>
<p>
Here is an example of the pvsbufread opcode. It does 'brassage' by switching between two buffers.
</p>
<div class="example">
<a id="id3130498"></a>
<p class="title">
<b>Example 468. Example of the pvsbufread opcode</b>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<pre class="programlisting">
fsig1 pvsanal asig1,1024,256,1024,1
fsig2 pvsanal asig2,1024,256,1024,1
ibuf1,kt1 pvsbuffer fsig1, 10 ; 10-sec buf with fsig1
ibuf2,kt2 pvsbuffer fsig2, 7 ; 7-sec buf with fsig2
khan init ibuf1 ; initialise handle to buf1
if ktrig > 0 then ; switch buffers according to trigger
khan = ibuf2
else
khan = ibuf1
endif
fsb pvsbufread kt1, khan ; read buffer
</pre>
</div>
</div>
<p><br class="example-break" />
</p>
<p>
Here is an example of the pvsbufread opcode. It uses the file <a class="ulink" href="examples/pvsbufread.csd" target="_top"><em class="citetitle">pvsbufread.csd</em></a>.
</p>
<div class="example">
<a id="id3130560"></a>
<p class="title">
<b>Example 469. Example of the pvsbufread opcode.</b>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<pre class="programlisting">
<span class="csdtag"><CsoundSynthesizer></span>
<span class="csdtag"><CsOptions></span>
<span class="comment">; Select audio/midi flags here according to platform</span>
<span class="comment">; Audio out Audio in</span>
-odac <span class="comment">;;;RT audio I/O</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o pvsbufread.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">ksmps</span> <span class="op">=</span> 16
<span class="ohdr">nchnls</span> <span class="op">=</span> 1
<span class="ohdr">0dbfs</span> <span class="op">=</span> 1
<span class="comment">;; example written by joachim heintz 2009</span>
<span class="oblock">opcode</span> FileToPvsBuf, iik, Siiii
<span class="comment">;;writes an audio file at the first k-cycle to a fft-buffer (via pvsbuffer)</span>
Sfile, ifftsize, ioverlap, iwinsize, iwinshape <span class="opc">xin</span>
ktimek <span class="opc">timeinstk</span>
<span class="octrl">if</span> ktimek <span class="op">==</span> 1 then
ilen <span class="opc">filelen</span> Sfile
kcycles <span class="op">=</span> ilen <span class="op">*</span> <span class="ohdr">kr</span><span class="comment">; number of k-cycles to write the fft-buffer</span>
kcount <span class="opc">init</span> 0
<span class="olabel">loop</span><span class="op">:</span>
ain <span class="opc">soundin</span> Sfile
fftin <span class="opc">pvsanal</span> ain, ifftsize, ioverlap, iwinsize, iwinshape
ibuf, ktim <span class="opc">pvsbuffer</span> fftin, ilen <span class="op">+</span> (ifftsize <span class="op">/</span> sr)
<span class="octrl">loop_lt</span> kcount, 1, kcycles, <span class="olabel">loop</span>
<span class="opc">xout</span> ibuf, ilen, ktim
<span class="octrl">endif</span>
<span class="oblock">endop</span>
<span class="oblock">instr</span> 1
ifftsize <span class="op">=</span> 1024
ioverlap <span class="op">=</span> ifftsize <span class="op">/</span> 4
iwinsize <span class="op">=</span> ifftsize
iwinshape <span class="op">=</span> 1<span class="comment">; von-Hann window</span>
ibuffer, ilen, k0 FileToPvsBuf "fox.wav", ifftsize, ioverlap, iwinsize, iwinshape
ktmpnt <span class="opc">linseg</span> ilen, p3, 0<span class="comment">; reads the buffer backwards in p3 seconds</span>
fread <span class="opc">pvsbufread</span> ktmpnt, ibuffer
aout <span class="opc">pvsynth</span> fread
<span class="opc">out</span> aout
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">i</span> 1 0 5
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
</div>
</div>
<p><br class="example-break" />
</p>
</div>
<div class="refsect1" title="See Also">
<a id="id3130598"></a>
<h2>See Also</h2>
<p>
<a class="link" href="pvsanal.html" title="pvsanal"><em class="citetitle">pvsanal</em></a>,
<a class="link" href="pvsynth.html" title="pvsynth"><em class="citetitle">pvsynth</em></a>,
<a class="link" href="pvsbuffer.html" title="pvsbuffer"><em class="citetitle">pvsbuffer</em></a>,
<a class="link" href="pvsadsyn.html" title="pvsadsyn"><em class="citetitle">pvsadsyn</em></a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="id3130640"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Victor Lazzarini</td>
</tr>
<tr>
<td>July 2007</td>
</tr>
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</p>
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