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Add configurable feedback high-pass cutoff with smoothing and WASM bindings #71

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1 change: 1 addition & 0 deletions core/include/orbit_delay_c_api.h
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,7 @@ bool orbit_set_feedback(OrbitDelayHandle* handle, float value);
bool orbit_set_feedback_drive(OrbitDelayHandle* handle, float value);
bool orbit_set_feedback_nonlinear_amount(OrbitDelayHandle* handle, float value);
bool orbit_set_feedback_comp_threshold(OrbitDelayHandle* handle, float value);
bool orbit_set_feedback_highpass_hz(OrbitDelayHandle* handle, float value);
bool orbit_set_mix(OrbitDelayHandle* handle, float value);
bool orbit_set_input_gain(OrbitDelayHandle* handle, float value);
bool orbit_set_output_gain(OrbitDelayHandle* handle, float value);
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6 changes: 6 additions & 0 deletions core/include/orbit_delay_core.h
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Expand Up @@ -36,6 +36,7 @@ class OrbitDelayCore {
void setFeedbackDrive(float value);
void setFeedbackNonlinearAmount(float value);
void setFeedbackCompThreshold(float value);
void setFeedbackHighpassHz(float value);
void setMix(float value);
void setInputGain(float value);
void setOutputGain(float value);
Expand Down Expand Up @@ -109,6 +110,8 @@ class OrbitDelayCore {
static constexpr float kDiffuserUpdateDelta = 0.01f;
static constexpr float kDiffuserCadenceUpdateDelta = 0.03f;
static constexpr float kHighpassCutoffHz = 30.0f;
static constexpr float kMinFeedbackHighpassHz = 20.0f;
static constexpr float kMaxFeedbackHighpassHz = 2000.0f;
static constexpr float kOrbitReadGuardMinSamples = 16.0f;
static constexpr float kOrbitReadGuardMaxSamples = 64.0f;
static constexpr float kHighpassUpdateDeltaHz = 1.0f;
Expand Down Expand Up @@ -172,6 +175,7 @@ class OrbitDelayCore {
float feedbackDrive_ = 1.0f;
float feedbackNonlinearAmount_ = 0.0f;
float feedbackCompThreshold_ = 1.0f;
float feedbackHighpassHz_ = kHighpassCutoffHz;
float mix_ = 0.35f;
float toneHz_ = 8000.0f;
float smear_ = 0.0f;
Expand Down Expand Up @@ -202,6 +206,7 @@ class OrbitDelayCore {
LinearSmoother feedbackDriveSm_;
LinearSmoother feedbackNonlinearAmountSm_;
LinearSmoother feedbackCompThresholdSm_;
LinearSmoother feedbackHighpassHzSm_;
LinearSmoother toneSm_;
LinearSmoother orbitSm_;
LinearSmoother offsetSm_;
Expand All @@ -227,6 +232,7 @@ class OrbitDelayCore {
std::atomic<float> pendingFeedbackDrive_{1.0f};
std::atomic<float> pendingFeedbackNonlinearAmount_{0.0f};
std::atomic<float> pendingFeedbackCompThreshold_{1.0f};
std::atomic<float> pendingFeedbackHighpassHz_{kHighpassCutoffHz};
std::atomic<float> pendingMix_{0.35f};
std::atomic<float> pendingInputGain_{1.0f};
std::atomic<float> pendingOutputGain_{1.0f};
Expand Down
8 changes: 8 additions & 0 deletions core/src/orbit_delay_c_api.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -173,6 +173,14 @@ bool orbit_set_feedback_comp_threshold(OrbitDelayHandle* handle, float value) {
return true;
}

bool orbit_set_feedback_highpass_hz(OrbitDelayHandle* handle, float value) {
if (handle == nullptr) {
return false;
}
handle->core.setFeedbackHighpassHz(value);
return true;
}

bool orbit_set_mix(OrbitDelayHandle* handle, float value) {
if (handle == nullptr) {
return false;
Expand Down
29 changes: 24 additions & 5 deletions core/src/orbit_delay_core.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ void OrbitDelayCore::applyPendingParamsIfNeeded() {
const float nextFeedbackDrive = pendingFeedbackDrive_.load(std::memory_order_relaxed);
const float nextFeedbackNonlinearAmount = pendingFeedbackNonlinearAmount_.load(std::memory_order_relaxed);
const float nextFeedbackCompThreshold = pendingFeedbackCompThreshold_.load(std::memory_order_relaxed);
const float nextFeedbackHighpassHz = pendingFeedbackHighpassHz_.load(std::memory_order_relaxed);
const float nextMix = pendingMix_.load(std::memory_order_relaxed);
const float nextInputGain = pendingInputGain_.load(std::memory_order_relaxed);
const float nextOutputGain = pendingOutputGain_.load(std::memory_order_relaxed);
Expand Down Expand Up @@ -198,6 +199,12 @@ void OrbitDelayCore::applyPendingParamsIfNeeded() {
feedbackCompThreshold_ = clampedFeedbackCompThreshold;
smoothTargetsChanged = true;
}
const float clampedFeedbackHighpassHz =
clampf(sanitizeFinite(nextFeedbackHighpassHz, feedbackHighpassHz_), kMinFeedbackHighpassHz, kMaxFeedbackHighpassHz);
if (feedbackHighpassHz_ != clampedFeedbackHighpassHz) {
feedbackHighpassHz_ = clampedFeedbackHighpassHz;
smoothTargetsChanged = true;
}
const float clampedMix = clampf(sanitizeFinite(nextMix, mix_), 0.0f, 1.0f);
if (mix_ != clampedMix) {
mix_ = clampedMix;
Expand Down Expand Up @@ -278,6 +285,7 @@ void OrbitDelayCore::syncDspParams() {
feedbackDriveSm_.configure(sampleRate_, kSmoothFeedbackNonlinearMs);
feedbackNonlinearAmountSm_.configure(sampleRate_, kSmoothFeedbackNonlinearMs);
feedbackCompThresholdSm_.configure(sampleRate_, kSmoothFeedbackNonlinearMs);
feedbackHighpassHzSm_.configure(sampleRate_, kSmoothToneMs);
feedbackLimiterL_.configure(sampleRate_);
feedbackLimiterR_.configure(sampleRate_);
toneSm_.configure(sampleRate_, kSmoothToneMs);
Expand All @@ -301,9 +309,10 @@ void OrbitDelayCore::syncDspParams() {
const float lowpassQ = feedbackLowpassQ();
lowpassL_.setParams(nyquistLimited, lowpassQ);
lowpassR_.setParams(nyquistLimited, lowpassQ);
highpassL_.setParams(kHighpassCutoffHz, kDefaultFeedbackLowpassQ);
highpassR_.setParams(kHighpassCutoffHz, kDefaultFeedbackLowpassQ);
appliedHighpassHz_ = kHighpassCutoffHz;
const float clampedHighpassHz = clampf(feedbackHighpassHz_, kMinFeedbackHighpassHz, clampf(0.49f * sampleRate_, kMinFeedbackHighpassHz, kMaxFeedbackHighpassHz));
highpassL_.setParams(clampedHighpassHz, kDefaultFeedbackLowpassQ);
highpassR_.setParams(clampedHighpassHz, kDefaultFeedbackLowpassQ);
appliedHighpassHz_ = clampedHighpassHz;
lowpassDirty_ = false;
}

Expand Down Expand Up @@ -331,6 +340,7 @@ void OrbitDelayCore::updateSmoothedTargetsIfDirty() {
feedbackDriveSm_.setTarget(feedbackDrive_);
feedbackNonlinearAmountSm_.setTarget(feedbackNonlinearAmount_);
feedbackCompThresholdSm_.setTarget(feedbackCompThreshold_);
feedbackHighpassHzSm_.setTarget(feedbackHighpassHz_);
mixSm_.setTarget(mix_);
inputGainSm_.setTarget(inputGain_);
outputGainSm_.setTarget(outputGain_);
Expand Down Expand Up @@ -360,7 +370,8 @@ OrbitDelayCore::SmoothedParams OrbitDelayCore::advanceSmoothers() {
heavyParamCadenceHit_ = advanceCadence();

maybeApplyLowpassCutoff(smoothedToneHz);
maybeApplyHighpassCutoff(kHighpassCutoffHz);
const float smoothedFeedbackHighpassHz = feedbackHighpassHzSm_.next();
maybeApplyHighpassCutoff(smoothedFeedbackHighpassHz);
maybeApplyDiffuserAmount(smoothedSmear);
return params;
}
Expand Down Expand Up @@ -406,7 +417,8 @@ void OrbitDelayCore::maybeApplyDiffuserAmount(float smoothedSmear) {
}

void OrbitDelayCore::maybeApplyHighpassCutoff(float targetHighpassHz) {
const float clampedHighpassHz = clampf(targetHighpassHz, 10.0f, clampf(0.49f * sampleRate_, 10.0f, 2000.0f));
const float clampedHighpassHz =
clampf(targetHighpassHz, kMinFeedbackHighpassHz, clampf(0.49f * sampleRate_, kMinFeedbackHighpassHz, kMaxFeedbackHighpassHz));
const float delta = std::fabs(clampedHighpassHz - appliedHighpassHz_);
if (lowpassDirty_ || (heavyParamCadenceHit_ && delta >= kHighpassUpdateDeltaHz)) {
highpassL_.setParams(clampedHighpassHz, kDefaultFeedbackLowpassQ);
Expand Down Expand Up @@ -438,6 +450,7 @@ void OrbitDelayCore::reset(float sampleRate) {
feedbackDriveSm_.reset(feedbackDrive_);
feedbackNonlinearAmountSm_.reset(feedbackNonlinearAmount_);
feedbackCompThresholdSm_.reset(feedbackCompThreshold_);
feedbackHighpassHzSm_.reset(feedbackHighpassHz_);
feedbackLimiterL_.reset();
feedbackLimiterR_.reset();
mixSm_.reset(mix_);
Expand Down Expand Up @@ -551,6 +564,12 @@ void OrbitDelayCore::setMix(float value) {
pendingParamVersion_.fetch_add(1u, std::memory_order_release);
}

void OrbitDelayCore::setFeedbackHighpassHz(float value) {
pendingFeedbackHighpassHz_.store(clampf(sanitizeFinite(value, feedbackHighpassHz_), kMinFeedbackHighpassHz, kMaxFeedbackHighpassHz),
std::memory_order_relaxed);
pendingParamVersion_.fetch_add(1u, std::memory_order_release);
}
Comment on lines +567 to +571

@gemini-code-assist gemini-code-assist Bot May 26, 2026

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high

Thread Safety / Data Race Issue

There is a potential data race on feedbackHighpassHz_. The function setFeedbackHighpassHz is called from the control/UI thread, but it reads feedbackHighpassHz_ (a non-atomic member variable) as a fallback value for sanitizeFinite. Meanwhile, the audio thread writes to feedbackHighpassHz_ in applyPendingParamsIfNeeded() on every processing block.

Reading a non-atomic variable that is concurrently written to by another thread is undefined behavior in C++.

Solution

Instead of falling back to the non-atomic feedbackHighpassHz_, you can safely fall back to the atomic pendingFeedbackHighpassHz_.load(std::memory_order_relaxed). This avoids the data race entirely and ensures thread safety.

Suggested change
void OrbitDelayCore::setFeedbackHighpassHz(float value) {
pendingFeedbackHighpassHz_.store(clampf(sanitizeFinite(value, feedbackHighpassHz_), kMinFeedbackHighpassHz, kMaxFeedbackHighpassHz),
std::memory_order_relaxed);
pendingParamVersion_.fetch_add(1u, std::memory_order_release);
}
void OrbitDelayCore::setFeedbackHighpassHz(float value) {
const float fallback = pendingFeedbackHighpassHz_.load(std::memory_order_relaxed);
pendingFeedbackHighpassHz_.store(clampf(sanitizeFinite(value, fallback), kMinFeedbackHighpassHz, kMaxFeedbackHighpassHz),
std::memory_order_relaxed);
pendingParamVersion_.fetch_add(1u, std::memory_order_release);
}


void OrbitDelayCore::setInputGain(float value) {
pendingInputGain_.store(clampf(sanitizeFinite(value, inputGain_), 0.0f, 4.0f), std::memory_order_relaxed);
pendingParamVersion_.fetch_add(1u, std::memory_order_release);
Expand Down
2 changes: 1 addition & 1 deletion targets/wasm/CMakeLists.txt
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Expand Up @@ -24,6 +24,6 @@ target_link_options(orbit_delay_wasm PRIVATE
"-sEXPORT_ES6=1"
"-sENVIRONMENT=web,worker,node"
"-sALLOW_MEMORY_GROWTH=1"
"-sEXPORTED_FUNCTIONS=['_malloc','_free','_orbit_wasm_init','_orbit_wasm_free','_orbit_wasm_reset','_orbit_wasm_process_stereo','_orbit_wasm_set_orbit','_orbit_wasm_set_offset_samples','_orbit_wasm_set_tempo_bpm','_orbit_wasm_set_note_division','_orbit_wasm_set_stereo_spread','_orbit_wasm_set_lfo_rate_hz','_orbit_wasm_set_lfo_depth_samples','_orbit_wasm_set_lfo_stereo_phase_offset','_orbit_wasm_set_feedback','_orbit_wasm_set_mix','_orbit_wasm_set_input_gain','_orbit_wasm_set_output_gain','_orbit_wasm_set_tone_hz','_orbit_wasm_set_smear_amount','_orbit_wasm_set_shimmer_mode','_orbit_wasm_set_diffuser_stages','_orbit_wasm_set_dc_block_enabled','_orbit_wasm_set_read_mode','_orbit_wasm_set_feedback_tap_mixer_enabled','_orbit_wasm_set_feedback_tap_mixer_amount']"
"-sEXPORTED_FUNCTIONS=['_malloc','_free','_orbit_wasm_init','_orbit_wasm_free','_orbit_wasm_reset','_orbit_wasm_process_stereo','_orbit_wasm_set_orbit','_orbit_wasm_set_offset_samples','_orbit_wasm_set_tempo_bpm','_orbit_wasm_set_note_division','_orbit_wasm_set_stereo_spread','_orbit_wasm_set_lfo_rate_hz','_orbit_wasm_set_lfo_depth_samples','_orbit_wasm_set_lfo_stereo_phase_offset','_orbit_wasm_set_feedback','_orbit_wasm_set_feedback_highpass_hz','_orbit_wasm_set_mix','_orbit_wasm_set_input_gain','_orbit_wasm_set_output_gain','_orbit_wasm_set_tone_hz','_orbit_wasm_set_smear_amount','_orbit_wasm_set_shimmer_mode','_orbit_wasm_set_diffuser_stages','_orbit_wasm_set_dc_block_enabled','_orbit_wasm_set_read_mode','_orbit_wasm_set_feedback_tap_mixer_enabled','_orbit_wasm_set_feedback_tap_mixer_amount']"
"-sEXPORTED_RUNTIME_METHODS=['ccall','cwrap']"
)
1 change: 1 addition & 0 deletions targets/wasm/js/ui.js
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Expand Up @@ -8,6 +8,7 @@ export function bindOrbitUiControls(api, root = document) {
['readMode', 'orbit_wasm_set_read_mode', (v) => Math.round(parseFloat(v))],
['stereoSpread', 'orbit_wasm_set_stereo_spread', parseFloat],
['feedback', 'orbit_wasm_set_feedback', parseFloat],
['feedbackHighpassHz', 'orbit_wasm_set_feedback_highpass_hz', parseFloat],
['mix', 'orbit_wasm_set_mix', parseFloat],
['inputGain', 'orbit_wasm_set_input_gain', parseFloat],
['outputGain', 'orbit_wasm_set_output_gain', parseFloat],
Expand Down
1 change: 1 addition & 0 deletions targets/wasm/orbit_delay_wasm.cpp
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Expand Up @@ -92,6 +92,7 @@ bool orbit_wasm_set_lfo_rate_hz(float value) { return orbit_set_lfo_rate_hz(g_ct
bool orbit_wasm_set_lfo_depth_samples(float value) { return orbit_set_lfo_depth_samples(g_ctx.handle, value); }
bool orbit_wasm_set_lfo_stereo_phase_offset(float value) { return orbit_set_lfo_stereo_phase_offset(g_ctx.handle, value); }
bool orbit_wasm_set_feedback(float value) { return orbit_set_feedback(g_ctx.handle, value); }
bool orbit_wasm_set_feedback_highpass_hz(float value) { return orbit_set_feedback_highpass_hz(g_ctx.handle, value); }
bool orbit_wasm_set_mix(float value) { return orbit_set_mix(g_ctx.handle, value); }
bool orbit_wasm_set_input_gain(float value) { return orbit_set_input_gain(g_ctx.handle, value); }
bool orbit_wasm_set_output_gain(float value) { return orbit_set_output_gain(g_ctx.handle, value); }
Expand Down
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