AudioEspressifFFT

Author: pschatzmann

examples/tests/fft/fft-espressif/fft-espressif.ino

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+#include "AudioTools.h"
+#include "AudioLibs/AudioEspressifFFT.h" // Using Espressif DSP Library
+
+AudioEspressifFFT fftc; 
+SineWaveGenerator<int16_t> sineWave(32000);
+GeneratedSoundStream<int16_t> in(sineWave);
+StreamCopy copier(fftc, in);
+uint16_t sample_rate = 44100;
+int bits_per_sample = 16;
+int channels = 1;
+float value = 0;
+
+// display fftc result
+void fftcResult(AudioFFTBase &fftc) {
+  int diff;
+  auto result = fftc.result();
+  if (result.magnitude > 100) {
+    Serial.print(result.frequency);
+    Serial.print(" ");
+    Serial.print(result.magnitude);
+    Serial.print(" => ");
+    Serial.print(result.frequencyAsNote(diff));
+    Serial.print(" diff: ");
+    Serial.print(diff);
+    Serial.print(" - time ms ");
+    Serial.print(fftc.resultTime() - fftc.resultTimeBegin());
+    Serial.println();
+
+  }
+}
+
+void setup() {
+  Serial.begin(115200);
+  AudioLogger::instance().begin(Serial, AudioLogger::Warning);
+
+  // set the frequency
+  sineWave.setFrequency(N_B4);
+
+  // Setup sine wave
+  auto cfg = in.defaultConfig();
+  cfg.channels = channels;
+  cfg.sample_rate = sample_rate;
+  in.begin(cfg);
+
+  // Setup FFT
+  auto tcfg = fftc.defaultConfig();
+  tcfg.copyFrom(cfg);
+  tcfg.length = 4096;
+  tcfg.callback = &fftcResult;
+  fftc.begin(tcfg);
+}
+
+void loop() { copier.copy(); }

src/AudioLibs/AudioEspressifFFT.h

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+#pragma once
+
+#include "AudioFFT.h"
+#include "esp_dsp.h"
+
+namespace audio_tools {
+
+/**
+ * @brief fft Driver for espressif dsp library: https://espressif-docs.readthedocs-hosted.com/projects/esp-dsp/en/latest/esp-dsp-apis.html
+ * @author Phil Schatzmann
+ * @copyright GPLv3
+ */
+class FFTDriverEspressifFFT : public FFTDriver {
+    public:
+        void begin(int len) override {
+            N = len;
+            if (p_data==nullptr){
+                p_data = new float[len*2];
+                if (p_data==nullptr){
+                    LOGE("not enough memory");
+                }
+            }
+            ret = dsps_fft2r_init_fc32(NULL, CONFIG_DSP_MAX_FFT_SIZE);
+            if (ret  != ESP_OK){
+                LOGE("dsps_fft2r_init_fc32 %d", ret);
+            }
+        }
+
+        void end() override {
+            dsps_fft2r_deinit_fc32();
+            if (p_data==nullptr){
+                delete p_data;
+                p_data = nullptr;
+            }
+        }
+
+        void setValue(int idx, int value) override {
+            if (idx<N){
+                p_data[idx*2 + 0] = value;
+                p_data[idx*2 + 1] = 0.0f;
+            }
+        }
+
+        void fft() override {
+            ret = dsps_fft2r_fc32(p_data, N);
+            if (ret  != ESP_OK){
+                LOGE("dsps_fft2r_fc32 %d", ret);
+            }
+            // Bit reverse 
+            ret = dsps_bit_rev_fc32(p_data, N);
+            if (ret  != ESP_OK){
+                LOGE("dsps_bit_rev_fc32 %d", ret);
+            }
+            // Convert one complex vector to two complex vectors
+            ret = dsps_cplx2reC_fc32(p_data, N);
+            if (ret  != ESP_OK){
+                LOGE("dsps_cplx2reC_fc32 %d", ret);
+            }
+        };
+
+        float magnitude(int idx) override { 
+            if (idx<N){
+                return sqrt(p_data[idx*2] * p_data[idx*2] + p_data[idx*2+1] * p_data[idx*2+1]);
+            } 
+            return 0.0f;
+        }
+
+        virtual bool isValid() override{ return p_data!=nullptr && ret==ESP_OK; }
+
+        esp_err_t ret;
+        float *p_data = nullptr;
+        int N=0;
+
+};
+/**
+ * @brief AudioFFT using FFTReal. The only specific functionality is the access to the dataArray
+ * @author Phil Schatzmann
+ * @copyright GPLv3
+ */
+class AudioEspressifFFT : public AudioFFTBase {
+    public:
+        AudioEspressifFFT():AudioFFTBase(new FFTDriverEspressifFFT()) {}
+
+        /// Provides the complex array returned by the FFT  
+        float *dataArray() {
+            return driverEx()->p_data;
+        }
+
+        FFTDriverEspressifFFT* driverEx() {
+            return (FFTDriverEspressifFFT*)driver();
+        }
+};
+
+
+}