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<div class="refentry" title="gbuzz">
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<h2>
<span class="refentrytitle">gbuzz</span>
</h2>
<p>gbuzz —
Output is a set of harmonically related cosine partials.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp25119448"></a>
<h2>Description</h2>
<p>
Output is a set of harmonically related cosine partials.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp25120200"></a>
<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>gbuzz</strong></span> xamp, xcps, knh, klh, kmul, ifn [, iphs]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp25130616"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ifn</em></span> -- table number of a stored function containing a cosine wave. A large table of at least 8192 points is recommended.
</p>
<p>
<span class="emphasis"><em>iphs</em></span> (optional, default=0) -- initial phase of the fundamental frequency, expressed as a fraction of a cycle (0 to 1). A negative value will cause phase initialization to be skipped. The default value is zero
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp25132520"></a>
<h2>Performance</h2>
<p>
The buzz units generate an additive set of harmonically related cosine partials of fundamental frequency <span class="emphasis"><em>xcps</em></span>, and whose amplitudes are scaled so their summation peak equals <span class="emphasis"><em>xamp</em></span>. The selection and strength of partials is determined by the following control parameters:
</p>
<p>
<span class="emphasis"><em>knh</em></span> -- total number of harmonics requested. If <span class="emphasis"><em>knh</em></span> is negative, the absolute value is used. If <span class="emphasis"><em>knh</em></span> is zero, a value of 1 is used.
</p>
<p>
<span class="emphasis"><em>klh</em></span> -- lowest harmonic present. Can be positive, zero or negative. In <span class="emphasis"><em>gbuzz</em></span> the set of partials can begin at any partial number and proceeds upwards; if <span class="emphasis"><em>klh</em></span> is negative, all partials below zero will reflect as positive partials without phase change (since cosine is an even function), and will add constructively to any positive partials in the set.
</p>
<p>
<span class="emphasis"><em>kmul</em></span> -- specifies the multiplier in the series of amplitude coefficients. This is a power series: if the <span class="emphasis"><em>klh</em></span>th partial has a strength coefficient of A, the (<span class="emphasis"><em>klh</em></span> + n)th partial will have a coefficient of A * (<span class="emphasis"><em>kmul</em></span> ** n), i.e. strength values trace an exponential curve. <span class="emphasis"><em>kmul</em></span> may be positive, zero or negative, and is not restricted to integers.
</p>
<p>
<a class="link" href="buzz.html" title="buzz"><em class="citetitle">buzz</em></a> and <span class="emphasis"><em>gbuzz </em></span>are useful as complex sound sources in subtractive synthesis. <span class="emphasis"><em>buzz</em></span> is a special case of the more general <span class="emphasis"><em>gbuzz</em></span> in which <span class="emphasis"><em>klh</em></span> = <span class="emphasis"><em>kmul</em></span> = 1; it thus produces a set of <span class="emphasis"><em>knh</em></span> equal-strength harmonic partials, beginning with the fundamental. (This is a band-limited pulse train; if the partials extend to the Nyquist, i.e. <span class="emphasis"><em>knh</em></span> = int (sr / 2 / fundamental freq.), the result is a real pulse train of amplitude <span class="emphasis"><em>xamp</em></span>.)
</p>
<p>
Although both <span class="emphasis"><em>knh</em></span> and <span class="emphasis"><em>klh</em></span> may be varied during performance, their internal values are necessarily integer and may cause <span class="quote">“<span class="quote">pops</span>”</span> due to discontinuities in the output. <span class="emphasis"><em>kmul,</em></span> however, can be varied during performance to good effect. <span class="emphasis"><em>gbuzz</em></span> can be amplitude- and/or frequency-modulated by either control or audio signals.
</p>
<p>
N.B. This unit has its analog in <a class="link" href="GEN11.html" title="GEN11"><em class="citetitle">GEN11</em></a>, in which the same set of cosines can be stored in a function table for sampling by an oscillator. Although computationally more efficient, the stored pulse train has a fixed spectral content, not a time-varying one as above.
</p>
</div>
<div class="refsect1" title="Examples">
<a id="idp25179160"></a>
<h2>Examples</h2>
<p>
Here is an example of the gbuzz opcode. It uses the file <a class="ulink" href="examples/gbuzz.csd" target="_top"><em class="citetitle">gbuzz.csd</em></a>.
</p>
<div class="example">
<a id="idp25180136"></a>
<p class="title">
<strong>Example 320. Example of the gbuzz opcode.</strong>
</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>
-odac <span class="comment">;;;realtime audio out</span>
<span class="comment">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o gbuzz.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> 32
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
<span class="ohdr">0dbfs</span> <span class="op">=</span>1
<span class="oblock">instr</span> 1
kcps <span class="op">=</span> 220
knh <span class="op">=</span> p4 <span class="comment">;total no. of harmonics</span>
klh <span class="op">=</span> p5 <span class="comment">;lowest harmonic</span>
kmul <span class="opc">line</span> 0, p3, 1 <span class="comment">;increase amplitude of</span>
<span class="comment">;higer partials</span>
asig <span class="opc">gbuzz</span> .6, kcps, knh, klh, kmul, 1
<span class="opc">outs</span> asig, asig
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="comment">; a cosine wave</span>
<span class="stamnt">f</span> 1 0 16384 11 1
<span class="stamnt">i</span> 1 0 3 3 1 <span class="comment">;3 harmonics, lowest harmonic=1</span>
<span class="stamnt">i</span> 1 + 3 30 1 <span class="comment">;30 harmonics, lowest harmonic=1</span>
<span class="stamnt">i</span> 1 + 3 3 2 <span class="comment">;3 harmonics, lowest harmonic=3</span>
<span class="stamnt">i</span> 1 + 3 30 2 <span class="comment">;30 harmonics, lowest harmonic=3</span>
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
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<p><br class="example-break" />
</p>
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<div class="refsect1" title="See Also">
<a id="idp25182408"></a>
<h2>See Also</h2>
<p>
<a class="link" href="buzz.html" title="buzz"><em class="citetitle">buzz</em></a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp25183456"></a>
<h2>Credits</h2>
<p>September 2003. Thanks to Kanata Motohashi for correcting the mentions of the <span class="emphasis"><em>kmul</em></span> parameter.</p>
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