Parameters with the same names overwrite each other in VST3Plugin.parameters

[pcmbs]

Hi,

thanks for the nice library!

There is a problem arising from implementing VST3Plugin.parameters as a python dict to store the parameters of a VST3 plugin. In fact, as the parameter names are used as keys, if a synthesizer has several parameters with the same name (e.g., Diva envelope 1 and 2 have the same names), they overwrite each other.

This is not a major problem since parameters can still be accessed with the _parameters attribute since this one is implemented as list, but I guess it would be good to find a workaround, e.g., modifying normalize_python_parameter_name() to take an additional index argument (passed to the method by to_python_parameter_name()) which would be prepended to the parameter name. This would generate keys of the form <parameter-index>-<normalized-name> and would ensure that each synthesizer parameter generates a unique key for the dict. This could be implemented as:

def to_python_parameter_name(parameter: _AudioProcessorParameter) -> Optional[str]:
    if not parameter.name and not parameter.label:
        return None

    name = parameter.name
    if parameter.label and not parameter.label.startswith(":"):
        name = "{} {}".format(name, parameter.label)
    return normalize_python_parameter_name(name, index)


def normalize_python_parameter_name(name: str, index: int) -> str:
    name = name.lower().strip()
    # Special case: some plugins expose parameters with "#"/"♯" or "b"/"♭" in their names.
    name = name.replace("#", "_sharp").replace("♯", "_sharp").replace("♭", "_flat")
    # Replace all non-alphanumeric characters with underscores
    name_chars = [
        c if (c.isalpha() or c.isnumeric()) and c.isprintable() and ord(c) < 128 else "_"
        for c in name
    ]
    # Remove any double-underscores:
    name_chars = [a for a, b in zip(name_chars, name_chars[1:]) if a != b or b != "_"] + [
        name_chars[-1]
    ]
    # Remove any leading or trailing underscores:
    name = "".join(name_chars).strip("_")
    # Prepend parameter index to the name
    name = "".join((str(index), "-", name))
    return name

Here is an example of the issue using Diva:

from pedalboard import load_plugin

synth = load_plugin(
    path_to_plugin_file="C:/Program Files/Audio Plugins/VST3/u-he/Diva(x64).vst3",
    plugin_name="Diva",
)

### Get Diva parameters (excl. MIDI CC) using the synth.parameters dictionary {param_name: param_object}
params_from_dict = [param for name, param in synth.parameters.items() if not name.startswith("cc_")]

### Get Diva parameters (excl. MIDI CC) using the synth._parameters list [param_object]
params_from_list = [param for param in synth._parameters if not param.name.startswith("CC ")]

# print number of parameters
print("Number of parameters in params dict: ", len(params_from_dict))  # >> 191
print("Number of parameters in params list: ", len(params_from_list))  # >> 282

# So let print out the parameter names for the first and second envelopes for both synth.parameters and synth._parameters
# We can see in the `from list` column that the parameters of the second envelop have the same names as the parameters of the first one,
# and since the parameter names are used as keys in synth.parameters(), they overwrite each other in the dict.
print(f"{'':<14}{'from list':<14}{'from dict':<18}{'same?'}")
for i in range(33, 55):
    print(
        f"Parameter {i}: {params_from_list[i].name:10} -> {params_from_dict[i].name:15} "
        f"| {params_from_list[i].name == params_from_dict[i].name}"
    )

which output

Number of parameters in params dict:  191
Number of parameters in params list:  282
              from list     from dict         same?
Parameter 33: Attack     -> Attack          | True
Parameter 34: Decay      -> Decay           | True
Parameter 35: Sustain    -> Sustain         | True
Parameter 36: Release    -> Release         | True
Parameter 37: Velocity   -> Velocity        | True
Parameter 38: Model      -> Model           | True
Parameter 39: Trigger    -> Trigger         | True
Parameter 40: Quantise   -> Quantise        | True
Parameter 41: Curve      -> Curve           | True
Parameter 42: Release On -> Release On      | True
Parameter 43: KeyFollow  -> KeyFollow       | True
Parameter 44: Attack     -> Sync            | False
Parameter 45: Decay      -> Restart         | False
Parameter 46: Sustain    -> Waveform        | False
Parameter 47: Release    -> Phase           | False
Parameter 48: Velocity   -> Delay           | False
Parameter 49: Model      -> DepthMod Src1   | False
Parameter 50: Trigger    -> DepthMod Dpt1   | False
Parameter 51: Quantise   -> Rate            | False
Parameter 52: Curve      -> FreqMod Src1    | False
Parameter 53: Release On -> FreqMod Dpt     | False
Parameter 54: KeyFollow  -> Polarity        | False