From db9d2d4e9fa4f335cb1cf265a92511c05f498809 Mon Sep 17 00:00:00 2001
From: Michael Sippel <micha@fragmental.art>
Date: Sun, 12 Jan 2025 05:08:18 +0100
Subject: [PATCH] wip noise gate
---
gate.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
gate.h | 21 +++++++++++++++++++++
guitfx.c | 31 +++++++++++++++++++++++++++----
meson.build | 1 +
4 files changed, 102 insertions(+), 4 deletions(-)
create mode 100644 gate.c
create mode 100644 gate.h
diff --git a/gate.c b/gate.c
new file mode 100644
index 0000000..1da00c3
--- /dev/null
+++ b/gate.c
@@ -0,0 +1,53 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "gate.h"
+#include <math.h>
+
+void gate_init(
+ struct gate * gate
+) {
+ gate->threshold = 0.0;
+ gate->enable_calibration = false;
+ gate->cur_state = false;
+ gate->cur_avg = 0;
+}
+
+void gate_process(
+ struct gate * gate,
+ size_t frame_size,
+ float const * in,
+ float * out
+) {
+ float sum = 0.0;
+
+ for( size_t i = 0; i < frame_size; ++i ) {
+ sum += fabs( in[i] );
+ }
+
+ gate->cur_avg = sum / frame_size;
+
+ if( gate->cur_avg > gate->threshold ) {
+
+ if( ! gate->cur_state ) {
+ gate->cur_state = true;
+ printf("GATE on\n");
+ }
+
+ for( size_t i = 0; i < frame_size; ++i ) {
+ out[i] = in[i];
+ }
+ }
+ else
+ {
+ if( gate->cur_state ) {
+ gate->cur_state = false;
+ printf("GATE off\n");
+ }
+
+ for( size_t i = 0; i < frame_size; ++i ) {
+ out[i] = 0.0;
+ }
+ }
+}
diff --git a/gate.h b/gate.h
new file mode 100644
index 0000000..492f959
--- /dev/null
+++ b/gate.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+
+struct gate {
+ float threshold;
+ bool enable_calibration;
+
+ float cur_avg;
+ bool cur_state;
+};
+
+void gate_init();
+void gate_process(
+ struct gate * gate,
+ size_t frame_size,
+ float const * in,
+ float * out
+);
diff --git a/guitfx.c b/guitfx.c
index a512079..41eb996 100644
--- a/guitfx.c
+++ b/guitfx.c
@@ -15,6 +15,7 @@
#include "delay.h"
#include "sust.h"
+#include "gate.h"
float envelope( float x );
struct data;
@@ -34,6 +35,7 @@ struct data {
uint64_t last_tap;
struct delay delay;
struct sust sust;
+ struct gate gate;
unsigned prog;
@@ -100,7 +102,16 @@ static void on_process(void *userdata, struct spa_io_position *position)
break;
case 0x42:
- // sust pedal
+
+ // noise gate calibration
+ if( data->prog == 2 ) {
+ if( midi_data[2] >= 64) {
+ data->gate.threshold = 0.0;//data->gate.cur_avg;
+ printf("calibrate noise gate: threshold = %f\n", data->gate.threshold);
+ }
+ }
+
+ // sust pedal
if( data->prog == 1 ) {
if( midi_data[2] >= 64) {
sust_swap( &data->sust );
@@ -133,6 +144,15 @@ static void on_process(void *userdata, struct spa_io_position *position)
case 0xc0:
// program change
+ if( midi_data[2] >= 64) {
+ sust_swap( &data->sust );
+ data->sust.playing = true;
+
+ data->sust.start_idx = data->sust.idx;
+ data->sust.idx = 0;
+ } else {
+ data->sust.playing = false;
+ }
printf("program change: %u\n", midi_data[1]);
data->prog = midi_data[1];
break;
@@ -155,11 +175,13 @@ static void on_process(void *userdata, struct spa_io_position *position)
float * const in = pw_filter_get_dsp_buffer(data->guit_in_port, n_samples);
- float tmp[n_samples];
+ float tmp1[n_samples];
+ float tmp2[n_samples];
float * out = pw_filter_get_dsp_buffer(data->out_port, n_samples);
if( in && out ) {
- sust_process( &data->sust, n_samples, in, tmp );
- delay_process( &data->delay, n_samples, tmp, out );
+ gate_process( &data->gate, n_samples, in, tmp1 );
+ sust_process( &data->sust, n_samples, in, tmp2 );
+ delay_process( &data->delay, n_samples, tmp2, out );
}
}
@@ -178,6 +200,7 @@ int main(int argc, char *argv[])
{
struct data data = { 0, };
+ gate_init( &data.gate );
delay_init( &data.delay );
sust_init( &data.sust );
data.prog = 0;
diff --git a/meson.build b/meson.build
index 9fc0dd8..d59ef2b 100644
--- a/meson.build
+++ b/meson.build
@@ -9,5 +9,6 @@ executable(
'guitfx.c',
'delay.c',
'sust.c',
+ 'gate.c',
dependencies : [pipewire_dep, m_dep],
)