kr — Sets the control rate.
These statements are global value assignments, made at the beginning of an orchestra, before any instrument block is defined. Their function is to set certain reserved symbol variables that are required for performance. Once set, these reserved symbols can be used in expressions anywhere in the orchestra.
kr = (optional) -- set control rate to iarg samples per second. The default value is 1000.
In addition, any global variable can be initialized by an init-time assignment anywhere before the first instr statement. All of the above assignments are run as instrument 0 (i-pass only) at the start of real performance.
Beginning with Csound version 3.46, kr can be omitted. Csound will use the default values, or calculate kr from defined ksmps and sr. It is usually better to just specify ksmps and sr and let csound calculate kr.