Add new Autotuner fx

Implements a new autotune, which is closer to the Antares original.

It doesn't use FFTs - instead everything happens in the time domain.
This version of the effect has options for transpose, key and scale
along with note as a target note. Performance should be better than the
other autotuner effect which exists in SP currently.

See @xavriley/qlibugens for the original plugin. Binaries are available
on the Releases page.

Author: xavriley

Diff for: BUILD-LINUX.md

@@ -45,7 +45,7 @@ few dependencies:
 * Ruby + Dev tools (2.5+)
 * Erlang + Dev tools (21+)
 * SuperCollider + SC3 plugins
-* 
+* (Optional) Additional SuperCollider plugins
 
 
 ### 1.1 Raspberry Pi OS
@@ -61,6 +61,16 @@ sudo apt-get install -y \
      compton pulseaudio-module-jack
 ```     
 
+### 1.2 (Optional) Additional SuperCollider Plugins
+
+Some audio effects and synthesizer are not distributed with the `sc3-plugins-server` package and prebuilt binaries are not provided with the Sonic Pi repo. To use these with your version of Sonic Pi, you can find build instructions at the following repositories:
+
+* https://github.com/xavriley/qlibugens/ - used by the `:autotuner_two` effect.
+* (more to follow as we implement other plugins)
+
+After building the plugins, make sure you copy them to your [SuperCollider Extensions folder](https://doc.sccode.org/Guides/UsingExtensions.html) before starting Sonic Pi.
+
+If you don't do this, everything else will still work as normal - you just won't be able to use these particular effects.
 
 ## 2. Preparing the Build
 

Diff for: app/server/ruby/lib/sonicpi/synths/synthinfo.rb

@@ -5419,6 +5419,149 @@ def specific_arg_info
       end
     end
 
+    class FXAutotuner2 < FXInfo
+      def name
+        "Autotuner2"
+      end
+
+      def introduced
+        Version.new(4,0,0)
+      end
+
+      def synth_name
+        "fx_autotuner_two"
+      end
+
+      def doc
+        "Another autotune effect. Used without any arguments, it tries to detect the pitch and shift it to the nearest exact note. This can help with out of tune singing, but it's also an interesting effect in its own right. When used with the note: arg, it tries to shift the input to match that note instead. This gives that classic \"robot singing\" sound that people associate with vocoders. This can then be changed using the control method to create new melodies.
+
+```
+with_fx :autotuner_two do |c|
+```
+
+```
+  sample \"~/Downloads/acappella.wav\" # any sample with a voice is good
+```
+
+```
+  sleep 4
+```
+
+```
+  # listen to standard auto-tune behaviour for 4 seconds
+```
+
+```
+  64.times do
+```
+
+```
+     # now start changing note: to get robot voice behaviour
+```
+
+```
+     control c, note: (scale :a2, :minor_pentatonic, num_octaves: 2).choose
+```
+
+```
+     sleep 0.5
+```
+
+```
+  end
+```
+
+```
+end
+```
+"
+      end
+
+      def arg_defaults
+        super.merge({
+          :note => -1,
+          :note_slide => 0,
+          :note_slide_shape => 1,
+          :note_slide_curve => 0,
+          :transpose => 0,
+          :key => 0,
+          :scale => 0
+        })
+      end
+
+      def munge_opts(studio, args_h)
+        keys = {
+          nil => nil,
+          :c => 0,
+          :cs => 1,
+          :db => 1,
+          :d => 2,
+          :ds => 3,
+          :eb => 3,
+          :e => 4,
+          :f => 5,
+          :fs => 6,
+          :gb => 6,
+          :g => 7,
+          :gs => 8,
+          :ab => 8,
+          :a => 9,
+          :as => 10,
+          :bb => 10,
+          :b => 11
+        }
+        args_h[:key] = keys[args_h[:key]]
+
+        scales = {
+          nil => nil,
+          :none => 0,
+          :chromatic => 0,
+          :major => 1,
+          :major_pentatonic => 2,
+          :minor_pentatonic => 3
+        }
+
+        args_h[:scale] = scales[args_h[:scale]]
+
+        puts args_h
+        args_h
+      end
+
+      def specific_arg_info
+        {
+          :note =>
+          {
+            :doc => "Midi note to shift pitch to. The quality of the sound depends on how stable the pitch of the input is. If set, this will override the scale and key options. Set to -1 to turn this off.",
+            :validations => [v_between_inclusive(:note, -2, 127)],
+            :modulatable => true
+          },
+
+          :key =>
+          {
+            :doc => "Key to lock the output pitches to. One of :c, :cs, :d, :e, :f, :fs, :g, :gs, :a, :as, or :b.",
+            :validations => [v_one_of(:key, [nil, :c, :cs, :db, :d, :ds, :eb, :e, :f, :fs, :gb, :g, :gs, :ab, :a, :as, :bb, :b,
+                                             0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])],
+            :modulatable => false
+          },
+
+          :scale =>
+          {
+            :doc => "Scale to lock the output pitches to. One of :none, :chromatic, :major, :major_pentatonic or :minor_pentatonic.",
+            :validations => [v_one_of(:scale, [nil, :none, :chromatic, :major, :major_pentatonic, :minor_pentatonic,
+                                               0, 1, 2, 3])],
+            :modulatable => false
+          },
+
+          :transpose =>
+          {
+            :doc => "Number of semitones to shift the output up or down, with a maximum of +24 (two octaves up) and a minimum of -24 (two octaves down).",
+            :validations => [v_between_inclusive(:transpose, -24, 24)],
+            :modulatable => true
+          }
+        }
+      end
+    end
+
     class FXMono < FXInfo
       def name
         "Mono"
@@ -8183,6 +8326,7 @@ class BaseInfo
         :fx_level => FXLevel.new,
         :fx_mono => FXMono.new,
         :fx_autotuner => FXAutotuner.new,
+        :fx_autotuner_two => FXAutotuner2.new,
         :fx_replace_level => FXLevel.new,
         :fx_echo => FXEcho.new,
         :fx_replace_echo => FXEcho.new,

Diff for: etc/synthdefs/compiled/sonic-pi-fx_autotuner_two.scsyndef

@@ -0,0 +1,92 @@
+// Autotune style plugin based on the orignal Antares patent (US Patent US5973252 - now expired). Uses Cycfi's Bitstream Autocorrelation (BACF) for pitch tracking.
+// See https://github.com/xavriley/qlibugens for details of the SC UGens
+
+(
+SynthDef('sonic-pi-fx_autotuner_two', {|
+    //standard args
+    pre_amp=1,
+    pre_amp_slide=0,
+    pre_amp_slide_shape=1,
+    pre_amp_slide_curve=0,
+    amp=1,
+    amp_slide=0,
+    amp_slide_shape=1,
+    amp_slide_curve=0,
+    mix=1,
+    mix_slide=0,
+    mix_slide_shape=1,
+    mix_slide_curve=0,
+    pre_mix=1,
+    pre_mix_slide=0,
+    pre_mix_slide_shape=1,
+    pre_mix_slide_curve=0
+    out_bus=0,
+    in_bus=0,
+    // args specific to this synth
+    note = -1,
+    note_slide=0,
+    note_slide_shape=1,
+    note_slide_curve=0,
+    min_freq = 50,
+    transpose=0,
+    key=0,
+    scale=0|
+
+    var pitch_ratio,
+    in,
+    snd,
+    freq,
+    // args for Sonic Pi plumbing
+    fxArgMix,
+    fxArgPreMix,
+    fxArgAmp,
+    fxArgPreAmp,
+    inLeft,
+    inRight,
+    fxArgInvPreMix,
+    fxArgBypassL,
+    fxArgBypassR,
+    dryL,
+    dryR,
+    wetL,
+    wetR,
+    finL,
+    finR;
+
+    // plumbing for Sonic Pi standard args
+    fxArgMix = VarLag.kr(mix.clip(0,1), mix_slide, mix_slide_curve, mix_slide_shape);
+    fxArgMix = LinLin.kr(fxArgMix, 0, 1, -1, 1);
+
+    fxArgPreMix = VarLag.kr(pre_mix.clip(0,1), pre_mix_slide, pre_mix_slide_curve, pre_mix_slide_shape);
+
+    fxArgAmp = VarLag.kr(amp, amp_slide, amp_slide_curve, amp_slide_shape);
+    fxArgPreAmp = VarLag.kr(pre_amp, pre_amp_slide, pre_amp_slide_curve, pre_amp_slide_shape);
+
+    # inLeft, inRight = In.ar(in_bus, 2) * fxArgPreAmp;
+    fxArgInvPreMix = 1 - fxArgPreMix;
+
+    fxArgBypassL = fxArgInvPreMix * inLeft;
+    fxArgBypassR = fxArgInvPreMix * inRight;
+
+    dryL = fxArgPreMix * inLeft;
+    dryR = fxArgPreMix * inRight;
+
+    // note represents a midi "target" pitch to tune to
+    // without that arg, it works as a normal autotune, locking the
+    // input to the nearest midi note
+    note = note.varlag(note_slide, note_slide_curve, note_slide_shape);
+
+    wetL = BitstreamPitchCorrection.ar(inLeft, min_freq, transpose: transpose, key: key, scale: scale, target_note: note);
+    wetR = wetL;
+
+    // plumbing for Sonic Pi output
+    wetL = wetL + fxArgBypassL;
+    wetR = wetR + fxArgBypassR;
+
+    finL = XFade2.ar(inLeft, wetL, fxArgMix, fxArgAmp);
+    finR = XFade2.ar(inRight, wetR, fxArgMix, fxArgAmp);
+
+    Out.ar(out_bus, [finL, finR]);
+}
+).writeDefFile("/Users/sam/Development/RPi/sonic-pi/etc/synthdefs/compiled/")
+)