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Csound

Generates Csound opcode plugins via the csdl.h C API. The opcode is discovered by Csound at startup from the OPCODE6DIR64 directory.

OS support: macOS, Linux

Prerequisites

  • Python >= 3.10

  • C++ compiler

  • make

  • Csound headers (csdl.h) -- from the CsoundLib64 framework (macOS), or the csound / libcsound-dev package (Linux)

Quick Start

# From a gen~ export
gen-dsp ./my_export -n myeffect -p csound
cd myeffect_csound && make all

# Verify Csound discovers the opcode
OPCODE6DIR64=. csound --list-opcodes | grep myeffect

Usage in a .csd File

Audio inputs map to a-rate args, parameters to k-rate args, audio outputs to a-rate outputs:

; Effect (2 audio in, 2 audio out, 8 k-rate params)
aout1, aout2 gigaverb ain1, ain2, kroomsize, krevtime, kdamping, ...

; Generator (0 audio in, 1 audio out, 5 k-rate params)
aout fm_synth kgate, kfreq, kmod_ratio, kmod_index, kamp

How It Works

  1. gen_ext_csound.cpp implements the OENTRY registration, init callback (creates gen~ state), and perf callback (per-ksmps-block processing)

  2. _ext_csound.cpp wraps genlib (header isolation pattern)

  3. OENTRY type strings are auto-generated from the gen~ manifest I/O counts (e.g. "aa" outputs, "aakkkkkkkk" inputs for 2in/2out/8params)

  4. Handles float (gen~/GENLIB_USE_FLOAT32) to MYFLT (double, Csound default) conversion

  5. Supports sample-accurate timing via ksmps_offset / ksmps_no_end

  6. The plugin registers via LINKAGE_BUILTIN which exports csound_opcode_init()

Header Discovery

The Makefile searches for Csound headers in this order:

  1. CSOUND_INCLUDE environment variable (explicit override)

  2. /Library/Frameworks/CsoundLib64.framework/Headers (macOS framework)

  3. $(brew --prefix)/include/csound (Homebrew)

  4. /usr/local/include/csound

  5. /usr/include/csound

Platform Key

"csound"