The SynthDef is module and struct for SuperCollider Synthesis Definitions.

This module includes functions for:

• converting binary scsyndef to a %SynthDef{} struct with parser/1 or from_file/1
• encoding %SynthDef{} to binary scsyndef file format.

The SynthDef struct contains the:

• the name of the synth definition
• number of constants
• list of constant values
• number of parameters
• [float32] * P - initial parameter values
• number of parameter names
• list of named parameters and their index
• number of unit generators (UGens)
• list of UGens (using the %SuperCollider.SynthDef.UGen{} struct)
• number of variants
• list of named varient specs (named key-value pairs with the value as a float.)

TODO: Currently there isn't a 'friendly' DSL for creating SynthDefs but that is on the roadmap!

example-create-a-synthdef-from-scratch

Example - create a SynthDef from scratch

This example:

• creates a brown-noise SynthDef
• encodes it to binary format
• sends it to SuperCollider (scsynth or supernova)
• play it by sending the :s_new command
• stop it by sending the :n_free command

# Define the brown noise SynthDef and call it 'ambient'
brown_noise_synthdef =
  [
    %SuperCollider.SynthDef{
      name: "ambient",
      constant_count: 1,
      constant_values_list: [0.2],
      parameter_count: 1,
      parameter_values_list: [0.0],
      parameter_names_count: 1,
      parameter_names_list: [
        %{_enum_index: 0, parameter_index: 0, parameter_name: "out"}
      ],
      ugen_count: 4,
      ugen_specs_list: [
        %SuperCollider.SynthDef.UGen{
          class_name: "Control",
          calculation_rate: 1,
          special_index: 0,
          inputs_count: 0,
          input_specs_list: [],
          outputs_count: 1,
          output_specs_list: [%{_enum_count: 0, calculation_rate: 1}]
        },
        %SuperCollider.SynthDef.UGen{
          class_name: "BrownNoise",
          calculation_rate: 2,
          special_index: 0,
          inputs_count: 0,
          input_specs_list: [],
          outputs_count: 1,
          output_specs_list: [%{_enum_count: 0, calculation_rate: 2}]
        },
        %SuperCollider.SynthDef.UGen{
          class_name: "BinaryOpUGen",
          calculation_rate: 2,
          special_index: 2,
          inputs_count: 2,
          input_specs_list: [
            %{_enum_count: 0, index: 1, output_index: 0, type: :ugen},
            %{_enum_count: 1, index: 0, type: :constant}
          ],
          outputs_count: 1,
          output_specs_list: [%{_enum_count: 0, calculation_rate: 2}]
        },
        %SuperCollider.SynthDef.UGen{
          class_name: "Out",
          calculation_rate: 2,
          special_index: 0,
          inputs_count: 2,
          input_specs_list: [
            %{_enum_count: 0, index: 0, output_index: 0, type: :ugen},
            %{_enum_count: 1, index: 2, output_index: 0, type: :ugen}
          ],
          outputs_count: 0,
          output_specs_list: []
        }
      ],
      varient_count: 0,
      varient_specs_list: []
    }
  ]

Encode the SynthDef into binary format:

sc_binary = SynthDef.to_binary(brown_noise_synthdef)

Assuming SuperCollider (scsynth or supernova) is running and SuperCollider.SoundServer has been started, e.g. through SuperCollider.start(), you can send this binary SynthDef to the server and play it!

Send the bimary to SuperCollider server (scsynth or supernova):

SuperCollider.command(:d_recv, sc_binary)

You can then play the brown noise by issuing the following command. This will load it on node 100:

SuperCollider.command(:s_new, ["ambient", 100, 1, 0, []])

You can stop it by freeing node 100:

SuperCollider.command(:n_free, 100)