<?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>Syntax of the Orchestra</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="PartOverview.html" title="Part I. Overview" /> <link rel="prev" href="Configuring.html" title="Configuring" /> <link rel="next" href="OrchIblock.html" title="Instrument and Opcode Block Statements" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Syntax of the Orchestra</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="Configuring.html">Prev</a> </td> <th width="60%" align="center">Part I. Overview</th> <td width="20%" align="right"> <a accesskey="n" href="OrchIblock.html">Next</a></td> </tr> </table> <hr /> </div> <div class="chapter"> <div class="titlepage"> <div> <div> <h2 class="title"><a id="OrchTop"></a>Syntax of the Orchestra</h2> </div> </div> </div> <p> The Csound orchestra (.orc) or the <span class="emphasis"><em><CsInstruments></em></span> section of a csd file, contains: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p>A <a class="link" href="OrchTop.html#OrchHeader" title="Orchestra Header Statements"><em class="citetitle">header section</em></a>, which specifies global options for instrument performance</p> </li> <li class="listitem"> <p>A list of <a class="link" href="OrchUDO.html" title="User Defined Opcodes (UDO)"><em class="citetitle">User defined opcodes</em></a> and <a class="link" href="OrchIblock.html" title="Instrument and Opcode Block Statements"><em class="citetitle">instrument blocks</em></a> containing UDO and instrument definitions.</p> </li> </ul> </div> <p> </p> <p> The orchestra header, instrument blocks, and UDOs contain <span class="emphasis"><em>Orchestra statements</em></span>. An <span class="emphasis"><em>orchestra statement</em></span> in Csound has the format: </p> <pre class="synopsis"> label: <span class="returnvalue">result</span> <code class="function">opcode</code> <em class="parameter"><code>argument1</code></em>, <em class="parameter"><code>argument2</code></em>, <em class="parameter"><code>...</code></em> ;comments </pre> <p> </p> <p> The label is optional and identifies the basic statement that follows as the potential target of a go-to operation (see <a class="link" href="ControlPgmctl.html" title="Program Flow Control"><em class="citetitle">Program Flow Control</em></a>). A label has no effect on the statement per se. </p> <p> Depending on their function, some opcodes produce no output, so they have no result value. Others take no arguments and only produce a result. </p> <p> Every orchestra statement must be on a single line, however long lines can be wrapped to a new line using the '\' character. This character indicates that the next line is part of the current one, this way you can split a line for easier reading, like this: </p> <pre class="programlisting"> a2 <span class="opc">oscbnk</span> kcps, 1.0, kfmd1, 0.0, 40, 203, 0.1, 0.2, kamfr, kamfr2, 148, \ 0, 0, 0, 0, 0, 0, -1, \ kfnum, 3, 4</pre> <p> </p> <p> Comments are optional and are for the purpose of letting the user document his orchestra code. Comments begin with a semicolon (;) or // and extend to the end of the line. Comments can optionally be in C-style, spanning multiple lines like this: </p> <pre class="programlisting"> <span class="comment">/* Anything in here -------- is a comment which can span several lines --------- */</span></pre> <p> </p> <p> The remainder (result, opcode, and arguments) form the basic statement. This also is optional, i.e. a line may have only a label or comment or be entirely blank. If present, the basic statement must be complete on one line, and is terminated by a carriage return and line feed. </p> <p> The opcode determines the operation to be performed; it usually takes some number of input values (or arguments, with a maximum value of about 800); and it usually has a result field variable to which it sends output values at some fixed rate. There are four possible rates: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p>once only, at orchestra setup time (effectively a permanent assignment)</p> </li> <li class="listitem"> <p>once at the beginning of each note (at initialization (init) time: i-rate)</p> </li> <li class="listitem"> <p>once every performance-time control loop (perf-time control rate, or k-rate)</p> </li> <li class="listitem"> <p>once each sound sample of every control loop (perf-time audio rate, or a-rate)</p> </li> </ol> </div> <p> </p> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="OrchHeader"></a>Orchestra Header Statements</h2> </div> </div> </div> <p> The <span class="emphasis"><em>Orchestra Header</em></span> contains global information that applies to all instruments and defines aspects of Csound output. It is sometimes referred to as <span class="emphasis"><em>instr 0</em></span>, because it behaves as an instrument, but without k- or a-rate processing (i.e. only opcodes and instructions that work at i-rate are allowed). </p> <p> An <span class="emphasis"><em>orchestra header statement</em></span> operates once only, at orchestra setup time. It is most commonly an assignment of some value to a <span class="emphasis"><em>global reserved symbol</em></span> , e.g. sr = 20000. All orchestra header statements belong to a pseudo instrument 0, an <span class="emphasis"><em>init</em></span> pass of which is run prior to all other instruments at score time 0. Any <span class="emphasis"><em>ordinary statement</em></span> can serve as an orchestra header statement, eg. gifreq = cpspch(8.09) provided it is an init-time only operation. Statements that are normally placed in an orchestra header are: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="Zerodbfs.html" title="0dbfs"> <em class="citetitle">0dbfs</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="A4.html" title="A4"> <em class="citetitle">A4</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="ctrlinit.html" title="ctrlinit"> <em class="citetitle">ctrlinit</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="ftgen.html" title="ftgen"> <em class="citetitle">ftgen</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="kr.html" title="kr"> <em class="citetitle">kr</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="ksmps.html" title="ksmps"> <em class="citetitle">ksmps</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="massign.html" title="massign"> <em class="citetitle">massign</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="nchnls.html" title="nchnls"> <em class="citetitle">nchnls</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="pgmassign.html" title="pgmassign"> <em class="citetitle">pgmassign</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="pset.html" title="pset"> <em class="citetitle">pset</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="seed.html" title="seed"> <em class="citetitle">seed</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="sr.html" title="sr"> <em class="citetitle">sr</em> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="strset.html" title="strset"> <em class="citetitle">strset</em> </a> </p> </li> </ul> </div> <p> For example, a Csound header may look like: </p> <pre class="programlisting"> xx<span class="ohdr">sr</span> = 44100 <span class="ohdr">kr</span> = 4410 <span class="ohdr">ksmps</span> = 10 <span class="ohdr">nchnls</span> = 2 <span class="ohdr">0dbfs</span> = 1 <span class="ohdr">massign</span> 1, 10</pre> <p> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="Configuring.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="PartOverview.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="OrchIblock.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Configuring </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Instrument and Opcode Block Statements</td> </tr> </table> </div> </body> </html>