example fft-effect

Author: pschatzmann

src/AudioTools/AudioLibs/AudioFFT.h

@@ -108,6 +108,7 @@ class FFTInverseOverlapAdder {
     if (window_function != nullptr) {
       add_value = value * window_function->factor(pos);
     }
+    assert(pos < len);
     data[pos] += add_value;
   }
 
@@ -228,7 +229,8 @@ class AudioFFTBase : public AudioStream {
     if (cfg.window_function_fft != nullptr) {
       cfg.window_function_fft->begin(cfg.length);
     }
-    if (cfg.window_function_ifft != nullptr) {
+    if (cfg.window_function_ifft != nullptr 
+    && cfg.window_function_ifft != cfg.window_function_fft) {
       cfg.window_function_ifft->begin(cfg.length);
     }
 
@@ -457,14 +459,13 @@ class AudioFFTBase : public AudioStream {
   bool setBin(int idx, float real, float img) {
     has_rfft_data = true;
     if (idx < 0 || idx >= size()) return false;
-    bool rc = p_driver->setBin(idx, real, img);
-    bool rc1 = p_driver->setBin(cfg.length - idx, real, img);
-    return rc && rc1;
+    bool rc_first_half = p_driver->setBin(idx, real, img);
+    bool rc_2nd_half = p_driver->setBin(cfg.length - idx, real, img);
+    return rc_first_half && rc_2nd_half;
   }
   /// sets the value of a bin
   bool setBin(int pos, FFTBin &bin) {
-    has_rfft_data = true;
-    return p_driver->setBin(pos, bin.real, bin.img);
+    return setBin(pos, bin.real, bin.img);
   }
   /// gets the value of a bin
   bool getBin(int pos, FFTBin &bin) { return p_driver->getBin(pos, bin); }
@@ -483,15 +484,15 @@ class AudioFFTBase : public AudioStream {
  protected:
   FFTDriver *p_driver = nullptr;
   int current_pos = 0;
-  AudioFFTConfig cfg;
+  int bins = 0;
   unsigned long timestamp_begin = 0l;
   unsigned long timestamp = 0l;
-  SingleBuffer<uint8_t> stride_buffer{0};
+  AudioFFTConfig cfg;
+  FFTInverseOverlapAdder rfft_add{0};
   Vector<float> l_magnitudes{0};
   Vector<float> step_data{0};
-  int bins = 0;
+  SingleBuffer<uint8_t> stride_buffer{0};
   RingBuffer<uint8_t> rfft_data{0};
-  FFTInverseOverlapAdder rfft_add{0};
   bool has_rfft_data = false;
 
   // Add samples to input data p_x - and process them if full
@@ -621,6 +622,7 @@ class AudioFFTBase : public AudioStream {
 
   // adds samples to stride buffer, returns true if the buffer is full
   bool writeStrideBuffer(uint8_t *buffer, size_t len) {
+    assert(stride_buffer.availableForWrite() >= len);
     stride_buffer.writeArray(buffer, len);
     return stride_buffer.isFull();
   }

src/AudioTools/AudioLibs/AudioRealFFT.h

@@ -58,7 +58,7 @@ class FFTDriverRealFFT : public FFTDriver {
 
         /// magnitude w/o sqrt
         float magnitudeFast(int idx) override {
-            return (v_x[idx] * v_x[idx] + v_f[idx] * v_f[idx]);
+            return ((v_x[idx] * v_x[idx]) + (v_f[idx] * v_f[idx]));
         }
 
         bool isValid() override{ return p_fft_object!=nullptr; }

src/AudioTools/AudioLibs/FFT/FFTWindows.h

@@ -31,10 +31,13 @@ class WindowFunction {
     this->i_half_samples = samples / 2;
   }
 
-  /// Provides the multipication factor at the indicated position. The result is symetrically mirrored around the center
+  /// Provides the multipication factor at the indicated position. The result is
+  /// symetrically mirrored around the center
   inline float factor(int idx) {
-    float result =  idx <= i_half_samples ? factor_internal(idx) : factor_internal(i_samples-idx-1);
-    return result>1.0f ? 1.0f : result;
+    assert(i_half_samples == i_samples / 2);
+    float result = idx <= i_half_samples ? factor_internal(idx)
+                                         : factor_internal(i_samples - idx - 1);
+    return result > 1.0f ? 1.0f : result;
   }
 
   /// Provides the number of samples (fft length)
@@ -57,7 +60,6 @@ class WindowFunction {
   inline float ratio(int idx) {
     return (static_cast<float>(idx)) / samples_minus_1;
   }
-
 };
 
 /**
@@ -70,28 +72,30 @@ class BufferedWindow : public WindowFunction {
  public:
   BufferedWindow(WindowFunction* wf) { p_wf = wf; }
 
-  const char* name() { 
+  const char* name() {
     static char buffer[80] = "Buffered ";
-    strncpy(buffer+9, p_wf->name(),69);
-    return buffer; 
+    strncpy(buffer + 9, p_wf->name(), 69);
+    return buffer;
   }
 
   virtual void begin(int samples) override {
     // process only if there is a change
     WindowFunction::begin(samples);
     if (p_wf->samples() != samples) {
       p_wf->begin(samples);
-      buffer.resize(i_half_samples + 1);
-      for (int j = 0; j <= i_half_samples; j++) {
-        buffer[j] = p_wf->factor(j);
+      int to_be_size = i_half_samples + 1;
+      if (buffer.size() != to_be_size) {
+        buffer.resize(to_be_size);
+        for (int j = 0; j <= i_half_samples; j++) {
+          buffer[j] = p_wf->factor(j);
+        }
       }
     }
   }
 
  protected:
   WindowFunction* p_wf = nullptr;
   Vector<float> buffer{0};
-  int len;
 
   float factor_internal(int idx) override {
     if (idx < 0 || idx > i_half_samples) return 0.0;
@@ -107,11 +111,12 @@ class BufferedWindow : public WindowFunction {
 class Rectange : public WindowFunction {
  public:
   Rectange() = default;
-  float factor_internal(int idx) { 
+  float factor_internal(int idx) {
     if (idx < 0 || idx >= i_samples) return 0;
-    return 1.0f; }
-    const char* name() { return "Rectange"; }
-  };
+    return 1.0f;
+  }
+  const char* name() { return "Rectange"; }
+};
 
 /**
  * @brief Hamming FFT Window function
@@ -136,7 +141,7 @@ class Hann : public WindowFunction {
  public:
   Hann() = default;
   const char* name() { return "Hann"; }
-  
+
   float factor_internal(int idx) {
     return 0.54f * (1.0f - cos(twoPi * ratio(idx)));
   }
@@ -153,8 +158,8 @@ class Triangle : public WindowFunction {
   const char* name() { return "Triangle"; }
   float factor_internal(int idx) {
     return 1.0f - ((2.0f * fabs((idx - 1) -
-                              (static_cast<float>(i_samples - 1) / 2.0f))) /
-                  samples_minus_1);
+                                (static_cast<float>(i_samples - 1) / 2.0f))) /
+                   samples_minus_1);
   }
 };
 
@@ -185,7 +190,7 @@ class Blackman : public WindowFunction {
  public:
   Blackman() = default;
   const char* name() { return "Blackman"; }
-  float factor_internal(int idx)override {
+  float factor_internal(int idx) override {
     float r = ratio(idx);
     return 0.42323f - (0.49755f * (cos(twoPi * r))) +
            (0.07922f * (cos(fourPi * r)));
@@ -201,7 +206,7 @@ class BlackmanNuttall : public WindowFunction {
  public:
   BlackmanNuttall() = default;
   const char* name() { return "BlackmanNuttall"; }
-  float factor_internal(int idx) override{
+  float factor_internal(int idx) override {
     float r = ratio(idx);
     return 0.3635819f - (0.4891775f * (cos(twoPi * r))) +
            (0.1365995f * (cos(fourPi * r))) - (0.0106411f * (cos(sixPi * r)));
@@ -217,7 +222,7 @@ class BlackmanHarris : public WindowFunction {
  public:
   BlackmanHarris() = default;
   const char* name() { return "BlackmanHarris"; }
-  float factor_internal(int idx) override{
+  float factor_internal(int idx) override {
     float r = ratio(idx);
     return 0.35875f - (0.48829f * (cos(twoPi * r))) +
            (0.14128f * (cos(fourPi * r))) - (0.01168f * (cos(sixPi * r)));
@@ -233,7 +238,7 @@ class FlatTop : public WindowFunction {
  public:
   FlatTop() = default;
   const char* name() { return "FlatTop"; }
-  float factor_internal(int idx) override{
+  float factor_internal(int idx) override {
     float r = ratio(idx);
     return 0.2810639f - (0.5208972f * cos(twoPi * r)) +
            (0.1980399f * cos(fourPi * r));
@@ -249,9 +254,10 @@ class Welch : public WindowFunction {
  public:
   Welch() = default;
   const char* name() { return "Welch"; }
-  float factor_internal(int idx) override{
-    float tmp = (((idx - 1) - samples_minus_1 / 2.0f) / (samples_minus_1 / 2.0f));
-    return 1.0f - (tmp*tmp);
+  float factor_internal(int idx) override {
+    float tmp =
+        (((idx - 1) - samples_minus_1 / 2.0f) / (samples_minus_1 / 2.0f));
+    return 1.0f - (tmp * tmp);
   }
 };
 

src/AudioTools/CoreAudio/AudioEffects/FFTEffects.h

@@ -6,6 +6,9 @@
 
 namespace audio_tools {
 
+static Hann fft_effects_hann;
+static BufferedWindow fft_effects_buffered_window{&fft_effects_hann};
+
 /**
  * @brief Common configuration for FFT effects
  * @ingroup transform
@@ -14,11 +17,7 @@ namespace audio_tools {
 struct FFTEffectConfig : public AudioInfo {
   int length = 1024;
   int stride = 512;
-  WindowFunction *window_function = &buffered_window;
-
- protected:
-  Hann hann;
-  BufferedWindow buffered_window{&hann};
+  WindowFunction *window_function = &fft_effects_buffered_window;
 };
 
 /***
@@ -59,7 +58,9 @@ class FFTEffect : public AudioOutput {
     fft_cfg.callback = effect_callback;
     LOGI("length: %d", fft_cfg.length);
     LOGI("stride: %d", fft_cfg.stride);
-    LOGI("window_function: %s", (fft_cfg.window_function!=nullptr) ? fft_cfg.window_function->name() : "-");
+    LOGI("window_function: %s", (fft_cfg.window_function != nullptr)
+                                    ? fft_cfg.window_function->name()
+                                    : "-");
     return fft.begin(fft_cfg);
   }
 
@@ -111,12 +112,17 @@ class FFTRobotize : public FFTEffect {
   /// Robotise the output
   void effect(AudioFFTBase &fft) {
     TRACED();
+    AudioFFTResult best = fft.result();
+
     FFTBin bin;
     for (int n = 0; n < fft.size(); n++) {
       float amplitude = fft.magnitude(n);
+
       // update new bin value
-      bin.real = amplitude;
-      bin.img = 0;
+      bin.real = amplitude / best.magnitude;
+      bin.img = 0.0;
+      Serial.println(bin.real);
+
       fft.setBin(n, bin);
     }
   }
@@ -153,6 +159,25 @@ class FFTWhisper : public FFTEffect {
   }
 };
 
+/**
+ * @brief Apply FFT and IFFT w/o any changes to the frequency domain
+ * @ingroup transform
+ * @author phil schatzmann
+ */
+
+class FFTNop : public FFTEffect {
+  friend FFTEffect;
+
+ public:
+  FFTNop(AudioStream &out) : FFTEffect(out) { addNotifyAudioChange(out); };
+  FFTNop(AudioOutput &out) : FFTEffect(out) { addNotifyAudioChange(out); };
+  FFTNop(Print &out) : FFTEffect(out) {};
+
+ protected:
+  /// Do nothing
+  void effect(AudioFFTBase &fft) {}
+};
+
 /**
  * @brief  Pitch Shift FFT Effect Configuration
  * @ingroup transform
@@ -189,7 +214,15 @@ class FFTPitchShift : public FFTEffect {
 
   bool begin(FFTPitchShiftConfig psConfig) {
     setShift(psConfig.shift);
-    return FFTEffect::begin(psConfig);
+    FFTEffect::begin(psConfig);
+    return begin();
+  }
+
+  bool begin() override {
+    bool rc = FFTEffect::begin();
+    // you can not shift more then you have bins
+    assert(abs(shift) < fft.size());
+    return rc;
   }
 
   /// defines how many bins should be shifted up (>0) or down (<0);
@@ -220,7 +253,7 @@ class FFTPitchShift : public FFTEffect {
       }
     } else if (shift > 0) {
       // copy bins: right shift
-      for (int n = max - shift; n <= 0; n--) {
+      for (int n = max - shift - 1; n >= 0; n--) {
         int to_bin = n + shift;
         assert(to_bin >= 0);
         assert(to_bin < max);

tests-cmake/CMakeLists.txt

@@ -25,6 +25,7 @@ add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/generator ${CMAKE_CURRENT_BINARY_DI
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/effects ${CMAKE_CURRENT_BINARY_DIR}/effects)
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/fft ${CMAKE_CURRENT_BINARY_DIR}/fft)
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/ifft ${CMAKE_CURRENT_BINARY_DIR}/ifft)
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/fft-effect ${CMAKE_CURRENT_BINARY_DIR}/fft-effect)
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/filter ${CMAKE_CURRENT_BINARY_DIR}/filter)
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/filter-wav ${CMAKE_CURRENT_BINARY_DIR}/filter-wav)
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/url-test ${CMAKE_CURRENT_BINARY_DIR}/url-test)

tests-cmake/fft-effect/CMakeLists.txt

@@ -0,0 +1,35 @@
+cmake_minimum_required(VERSION 3.20)
+
+
+# set the project name
+project(fft-effect)
+set (CMAKE_CXX_STANDARD 11)
+set (CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -O0 -ldl -lpthread -lm -fno-omit-frame-pointer -fsanitize=address")
+set (CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -O0 -ldl -lpthread -lm -fno-omit-frame-pointer -fsanitize=address")
+set (CMAKE_LINKER_FLAGS_DEBUG "${CMAKE_LINKER_FLAGS_DEBUG} -fno-omit-frame-pointer -fsanitize=address")
+
+# Emulator is not necessary for -DIS_MIN_DESKTOP
+set(ADD_ARDUINO_EMULATOR OFF CACHE BOOL "Add Arduino Emulator Library") 
+set(ADD_PORTAUDIO OFF CACHE BOOL "No Portaudio") 
+
+# Build with arduino-audio-tools
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+    add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/../.. ${CMAKE_CURRENT_BINARY_DIR}/arduino-audio-tools )
+endif()
+
+# Download miniaudio.h
+file(DOWNLOAD https://raw.githubusercontent.com/mackron/miniaudio/master/miniaudio.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/miniaudio.h)
+
+
+# build sketch as executable
+add_executable (fft-effect fft-effect.cpp)
+
+# set preprocessor defines
+target_compile_definitions(fft-effect PUBLIC -DIS_MIN_DESKTOP)
+
+# specify libraries
+target_link_libraries(fft-effect arduino-audio-tools)
+
+# access to miniaudio in sketch directory
+target_include_directories(fft-effect PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})