From 333ff2c05ec8c4b7846f9cf2e5fb307205b1ddfe Mon Sep 17 00:00:00 2001
From: Robbert van der Helm <mail@robbertvanderhelm.nl>
Date: Wed, 9 Nov 2022 18:38:44 +0100
Subject: [PATCH] Add an octave shift to Buffr Glitch

---
 plugins/buffr_glitch/src/buffer.rs | 11 +++++++----
 plugins/buffr_glitch/src/lib.rs    | 23 +++++++++++++++++++++--
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/plugins/buffr_glitch/src/buffer.rs b/plugins/buffr_glitch/src/buffer.rs
index 704e3c45..ce852968 100644
--- a/plugins/buffr_glitch/src/buffer.rs
+++ b/plugins/buffr_glitch/src/buffer.rs
@@ -16,7 +16,7 @@
 
 use nih_plug::prelude::*;
 
-use crate::NormalizationMode;
+use crate::{NormalizationMode, MAX_OCTAVE_SHIFT};
 
 /// A super simple ring buffer abstraction that records audio into a recording ring buffer, and then
 /// copies audio to a playback buffer when a note is pressed so audio can be repeated while still
@@ -47,9 +47,12 @@ impl RingBuffer {
     /// MIDI note 0 at the specified sample rate, rounded up to a power of two. Make sure to call
     /// [`reset()`][Self::reset()] after this.
     pub fn resize(&mut self, num_channels: usize, sample_rate: f32) {
-        let note_frequency = util::midi_note_to_freq(0);
-        let note_period_samples = (note_frequency.recip() * sample_rate).ceil() as usize;
-        let buffer_len = note_period_samples.next_power_of_two();
+        // NOTE: We need to take the octave shift into account
+        let lowest_note_frequency =
+            util::midi_note_to_freq(0) / 2.0f32.powi(MAX_OCTAVE_SHIFT as i32);
+        let loest_note_period_samples =
+            (lowest_note_frequency.recip() * sample_rate).ceil() as usize;
+        let buffer_len = loest_note_period_samples.next_power_of_two();
 
         // Used later to compute period sizes in samples based on frequencies
         self.sample_rate = sample_rate;
diff --git a/plugins/buffr_glitch/src/lib.rs b/plugins/buffr_glitch/src/lib.rs
index 637b265a..da2f8a55 100644
--- a/plugins/buffr_glitch/src/lib.rs
+++ b/plugins/buffr_glitch/src/lib.rs
@@ -19,6 +19,10 @@ use std::sync::Arc;
 
 mod buffer;
 
+/// The maximum number of octaves the sample can be pitched down. This is used in calculating the
+/// recording buffer's size.
+pub const MAX_OCTAVE_SHIFT: u32 = 2;
+
 struct BuffrGlitch {
     params: Arc<BuffrGlitchParams>,
 
@@ -38,6 +42,10 @@ struct BuffrGlitchParams {
     /// Controls if and how grains are normalization.
     #[id = "normalization_mode"]
     normalization_mode: EnumParam<NormalizationMode>,
+    /// The number of octaves the input signal should be increased or decreased by. Useful to allow
+    /// larger grain sizes.
+    #[id = "octave_shift"]
+    octave_shift: IntParam,
 }
 
 /// Controls how grains are normalized.
@@ -69,6 +77,14 @@ impl Default for BuffrGlitchParams {
     fn default() -> Self {
         Self {
             normalization_mode: EnumParam::new("Normalization", NormalizationMode::Auto),
+            octave_shift: IntParam::new(
+                "Octave Shift",
+                0,
+                IntRange::Linear {
+                    min: -(MAX_OCTAVE_SHIFT as i32),
+                    max: MAX_OCTAVE_SHIFT as i32,
+                },
+            ),
         }
     }
 }
@@ -140,9 +156,12 @@ impl Plugin for BuffrGlitch {
                         self.midi_note_id = Some(note);
 
                         // We'll copy audio to the playback buffer to match the pitch of the note
-                        // that was just played
+                        // that was just played. The octave shift parameter makes it possible to get
+                        // larger window sizes.
+                        let note_frequency = util::midi_note_to_freq(note)
+                            * 2.0f32.powi(self.params.octave_shift.value());
                         self.buffer.prepare_playback(
-                            util::midi_note_to_freq(note),
+                            note_frequency,
                             self.params.normalization_mode.value(),
                         );
                     }