101 lines
2.7 KiB
Nim
101 lines
2.7 KiB
Nim
## A simple multi-mode audio filter LV2 plugin
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import nymph
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import paramsmooth
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import svf
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const PluginUri = "urn:nymph:examples:multimodefilter"
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type
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SampleBuffer = UncheckedArray[cfloat]
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PluginPort {.pure.} = enum
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Input, Output, Cutoff, Q, Mode
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SVFPlugin = object
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input: ptr SampleBuffer
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output: ptr SampleBuffer
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cutoff: ptr cfloat
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q: ptr cfloat
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mode: ptr cfloat
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svf: SVFilter
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smoothCutoff: ParamSmooth
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proc instantiate(descriptor: ptr Lv2Descriptor; sampleRate: cdouble;
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bundlePath: cstring; features: ptr UncheckedArray[ptr Lv2Feature]):
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Lv2Handle {.cdecl.} =
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try:
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let plug = createShared(SVFPlugin)
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plug.svf = initSVFilter(fmLowPass, sampleRate)
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plug.smoothCutoff = initParamSmooth(20.0, sampleRate)
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return cast[Lv2Handle](plug)
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except OutOfMemDefect:
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return nil
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proc connectPort(instance: Lv2Handle; port: cuint;
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dataLocation: pointer) {.cdecl.} =
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let plug = cast[ptr SVFPlugin](instance)
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case cast[PluginPort](port)
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of PluginPort.Input:
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plug.input = cast[ptr SampleBuffer](dataLocation)
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of PluginPort.Output:
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plug.output = cast[ptr SampleBuffer](dataLocation)
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of PluginPort.Cutoff:
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plug.cutoff = cast[ptr cfloat](dataLocation)
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of PluginPort.Q:
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plug.q = cast[ptr cfloat](dataLocation)
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of PluginPort.Mode:
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plug.mode = cast[ptr cfloat](dataLocation)
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proc activate(instance: Lv2Handle) {.cdecl.} =
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let plug = cast[ptr SVFPlugin](instance)
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plug.svf.reset()
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plug.svf.setMode(fmLowPass)
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plug.svf.setCutoff(7_000.0)
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plug.svf.setQ(0.8)
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plug.svf.calcCoef()
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proc run(instance: Lv2Handle; nSamples: cuint) {.cdecl.} =
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let plug = cast[ptr SVFPlugin](instance)
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let cutoff = plug.cutoff[].clamp(16.0, 7_000.0)
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plug.svf.setMode(plug.mode[].int.clamp(0, 3).FilterMode)
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plug.svf.setQ(plug.q[].clamp(0.8, 10.0))
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for pos in 0 ..< nSamples:
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plug.svf.setCutoff(plug.smoothCutoff.process(cutoff))
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plug.svf.calcCoef()
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plug.output[pos] = plug.svf.process(plug.input[pos])
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proc cleanup(instance: Lv2Handle) {.cdecl.} =
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freeShared(cast[ptr SVFPlugin](instance))
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proc NimMain() {.cdecl, importc.}
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let descriptor = Lv2Descriptor(
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uri: cstring(PluginUri),
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instantiate: instantiate,
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connectPort: connectPort,
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activate: activate,
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run: run,
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deactivate: nil,
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cleanup: cleanup,
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extensionData: nil,
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)
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proc lv2Descriptor(index: cuint): ptr Lv2Descriptor {.
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cdecl, exportc, dynlib, extern: "lv2_descriptor".} =
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if index == 0:
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NimMain()
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return addr(descriptor)
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return nil
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