pke: audio: fx boilerplate, low-pass spatial

1 files changed, 22 insertions, 0 deletions

diff --git a/src/audio-impl-shared.cpp b/src/audio-impl-shared.cpp
new file mode 100644
index 0000000..0c3c730
--- /dev/null
+++ b/src/audio-impl-shared.cpp
@@ -0,0 +1,22 @@
+
+#include "audio-impl-shared.hpp"
+
+float pke_audio_fx_reverb(float *buffer, uint64_t buffer_len, uint64_t buffer_idx, pke_audio_fx_params_reverb *params) {
+	if (buffer_idx >= buffer_len-1) return 0.f;
+	// simple feedback
+	return buffer[buffer_idx - 1] * params->reverb_strength;
+}
+
+float pke_audio_fx_delay(float *buffer, uint64_t buffer_len, uint64_t buffer_idx, pke_audio_fx_params_delay *params) {
+	if (buffer_idx >= buffer_len-1) return 0.f;
+	return buffer[buffer_idx - params->delay_frames];
+}
+
+float pke_audio_fx_low_pass_filter(float *buffer, uint64_t buffer_len, uint64_t buffer_idx, pke_audio_fx_params_low_pass_filter *params) {
+	if (buffer_idx >= buffer_len-1) return 0.f;
+	float rc = 1.f / std::numbers::pi * 2.0 * params->cutoff_freq;
+	float dt = 1.f / 48000.f; // TODO reference global or pass this in
+	float alpha = dt / (rc + dt);
+	params->prev_output = (alpha * buffer[buffer_idx]) + ((1.f - alpha) * params->prev_output);
+	return params->prev_output;
+}