diff --git a/Source/PS_Source/ProcessedStretch.h b/Source/PS_Source/ProcessedStretch.h
index ea28951..1ed4360 100644
--- a/Source/PS_Source/ProcessedStretch.h
+++ b/Source/PS_Source/ProcessedStretch.h
@@ -247,7 +247,7 @@ inline void spectrum_spread(int nfreq, double samplerate,
 };
 
 
-inline void spectrum_do_compressor(ProcessParameters& pars, int nfreq, REALTYPE *freq1, REALTYPE *freq2) {
+inline void spectrum_do_compressor(const ProcessParameters& pars, int nfreq, REALTYPE *freq1, REALTYPE *freq2) {
 	REALTYPE rms = 0.0;
 	for (int i = 0; i<nfreq; i++) rms += freq1[i] * freq1[i];
 	rms = sqrt(rms / nfreq)*0.1f;
@@ -257,7 +257,7 @@ inline void spectrum_do_compressor(ProcessParameters& pars, int nfreq, REALTYPE
 	for (int i = 0; i<nfreq; i++) freq2[i] = freq1[i] * _rap;
 };
 
-inline void spectrum_do_tonal_vs_noise(ProcessParameters& pars, int nfreq, double samplerate,
+inline void spectrum_do_tonal_vs_noise(const ProcessParameters& pars, int nfreq, double samplerate,
 	std::vector<REALTYPE>& tmpfreq1,
 	REALTYPE *freq1, REALTYPE *freq2) {
 	spectrum_spread(nfreq, samplerate, tmpfreq1, freq1, tmpfreq1.data(), pars.tonal_vs_noise.bandwidth);
@@ -291,7 +291,7 @@ inline void spectrum_do_tonal_vs_noise(ProcessParameters& pars, int nfreq, doubl
 
 };
 
-inline void spectrum_do_harmonics(ProcessParameters& pars, std::vector<REALTYPE>& tmpfreq1, int nfreq, double samplerate, REALTYPE *freq1, REALTYPE *freq2) {
+inline void spectrum_do_harmonics(const ProcessParameters& pars, std::vector<REALTYPE>& tmpfreq1, int nfreq, double samplerate, REALTYPE *freq1, REALTYPE *freq2) {
 	REALTYPE freq = pars.harmonics.freq;
 	REALTYPE bandwidth = pars.harmonics.bandwidth;
 	int nharmonics = pars.harmonics.nharmonics;
@@ -347,7 +347,7 @@ inline void spectrum_zero(int nfreq,REALTYPE *freq1) {
 	for (int i = 0; i<nfreq; i++) freq1[i] = 0.0;
 };
 
-inline void spectrum_do_freq_shift(ProcessParameters& pars, int nfreq, double samplerate, REALTYPE *freq1, REALTYPE *freq2) {
+inline void spectrum_do_freq_shift(const ProcessParameters& pars, int nfreq, double samplerate, REALTYPE *freq1, REALTYPE *freq2) {
 	spectrum_zero(nfreq, freq2);
 	int ifreq = (int)(pars.freq_shift.Hz / (samplerate*0.5)*nfreq);
 	for (int i = 0; i<nfreq; i++) {
@@ -356,7 +356,7 @@ inline void spectrum_do_freq_shift(ProcessParameters& pars, int nfreq, double sa
 	};
 };
 
-inline void spectrum_do_pitch_shift(ProcessParameters& pars, int nfreq, REALTYPE *freq1, REALTYPE *freq2, REALTYPE _rap) {
+inline void spectrum_do_pitch_shift(const ProcessParameters& pars, int nfreq, REALTYPE *freq1, REALTYPE *freq2, REALTYPE _rap) {
 	spectrum_zero(nfreq,freq2);
 	if (_rap<1.0) {//down
 		for (int i = 0; i<nfreq; i++) {
@@ -374,7 +374,7 @@ inline void spectrum_do_pitch_shift(ProcessParameters& pars, int nfreq, REALTYPE
 	};
 };
 
-inline void spectrum_do_octave(ProcessParameters& pars, int nfreq, double samplerate, 
+inline void spectrum_do_octave(const ProcessParameters& pars, int nfreq, double samplerate, 
 	std::vector<REALTYPE>& sumfreq, 
 	std::vector<REALTYPE>& tmpfreq1,
 	REALTYPE *freq1, REALTYPE *freq2) {
@@ -408,7 +408,7 @@ inline void spectrum_do_octave(ProcessParameters& pars, int nfreq, double sample
 	for (int i = 0; i<nfreq; i++) freq2[i] = sumfreq[i] / sum;
 };
 
-inline void spectrum_do_filter(ProcessParameters& pars, int nfreq, double samplerate, REALTYPE *freq1, REALTYPE *freq2) {
+inline void spectrum_do_filter(const ProcessParameters& pars, int nfreq, double samplerate, REALTYPE *freq1, REALTYPE *freq2) {
 	REALTYPE low = 0, high = 0;
 	if (pars.filter.low<pars.filter.high) {//sort the low/high freqs
 		low = pars.filter.low;
diff --git a/Source/PS_Source/StretchSource.cpp b/Source/PS_Source/StretchSource.cpp
index 0dcfe91..fa53f6a 100644
--- a/Source/PS_Source/StretchSource.cpp
+++ b/Source/PS_Source/StretchSource.cpp
@@ -476,7 +476,7 @@ void StretchAudioSource::setProcessParameters(ProcessParameters * pars)
 	++m_param_change_count;
 }
 
-ProcessParameters StretchAudioSource::getProcessParameters()
+const ProcessParameters& StretchAudioSource::getProcessParameters()
 {
 	return m_ppar;
 }
diff --git a/Source/PS_Source/StretchSource.h b/Source/PS_Source/StretchSource.h
index e44d5f3..6112632 100644
--- a/Source/PS_Source/StretchSource.h
+++ b/Source/PS_Source/StretchSource.h
@@ -59,7 +59,7 @@ public:
 	void setRate(double rate);
 	double getRate() { return m_playrate; }
 	void setProcessParameters(ProcessParameters* pars);
-	ProcessParameters getProcessParameters();
+	const ProcessParameters& getProcessParameters();
 	void setFFTSize(int size);
 	int getFFTSize() { return m_process_fftsize; }
 	
diff --git a/Source/PluginEditor.cpp b/Source/PluginEditor.cpp
index 4588856..520092d 100644
--- a/Source/PluginEditor.cpp
+++ b/Source/PluginEditor.cpp
@@ -444,7 +444,7 @@ SpectralVisualizer::SpectralVisualizer()
 	m_img = Image(Image::RGB, 500, 200, true);
 }
 
-void SpectralVisualizer::setState(ProcessParameters & pars, int nfreqs, double samplerate)
+void SpectralVisualizer::setState(const ProcessParameters & pars, int nfreqs, double samplerate)
 {
 	double t0 = Time::getMillisecondCounterHiRes();
 	double hz = 440.0;
diff --git a/Source/PluginEditor.h b/Source/PluginEditor.h
index 420573e..4bb9e58 100644
--- a/Source/PluginEditor.h
+++ b/Source/PluginEditor.h
@@ -19,7 +19,7 @@ class SpectralVisualizer : public Component
 {
 public:
 	SpectralVisualizer();
-	void setState(ProcessParameters& pars, int nfreqs, double samplerate);
+	void setState(const ProcessParameters& pars, int nfreqs, double samplerate);
 	void paint(Graphics& g) override;
 	
 private: