snapshot

libraries/audio-tools/examples/tests/fft/fft-topn/fft-topn.ino

@@ -0,0 +1,62 @@
+
+#include "AudioTools.h"
+#include "AudioTools/AudioLibs/AudioRealFFT.h" // using RealFFT
+
+AudioRealFFT fft; // or AudioKissFFT
+SineWaveGenerator<int16_t> sineWave(32000);
+GeneratedSoundStream<int16_t> in(sineWave);
+StreamCopy copier(fft, in);
+AudioInfo info(44100, 1, 16);
+float value = 0;
+static const int N = 5;
+
+// check fft result
+void fftResult(AudioFFTBase &fft) {
+    // build result array
+    AudioFFTResult all[fft.size()];
+    for (int j=0;j<fft.size();j++){
+        all[j].bin = j;
+        all[j].magnitude = fft.magnitude(j);
+        all[j].frequency = fft.frequency(j);
+    }
+    // sort descending
+    std::sort(all, all + fft.size(), [](AudioFFTResult a, AudioFFTResult b){ return a.magnitude > b.magnitude; });
+
+    // get top 5
+    AudioFFTResult topn[N];
+    fft.resultArray(topn);
+
+    // compare the topn with sorted result
+    for (int j=0;j<N;j++){
+        Serial.print(all[j].bin);
+        Serial.print(":");
+        Serial.print(topn[j].bin);
+        Serial.print(" ");
+        assert(all[j].bin==topn[j].bin);
+    }
+    Serial.print(" -> TOP: ");
+    Serial.println(fft.result().bin);
+
+}
+
+void setup() {
+  Serial.begin(115200);
+  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Warning);
+
+  // set the frequency
+  sineWave.setFrequency(N_B4);
+
+  // Setup sine wave
+  auto cfg = in.defaultConfig();
+  cfg.copyFrom(info);
+  in.begin(cfg);
+
+  // Setup FFT
+  auto tcfg = fft.defaultConfig();
+  tcfg.copyFrom(info);
+  tcfg.length = 512;
+  tcfg.callback = &fftResult;
+  fft.begin(tcfg);
+}
+
+void loop() { copier.copy(); }