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save 1KB of RAM

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save one KB (4*256 bytes) by not storing the "upper half" of FFT results. Only the lower half has interesting results.
This commit is contained in:
Frank 2022-08-10 18:14:28 +02:00
parent 5e6532959b
commit ecce3243de
1 changed files with 4 additions and 3 deletions
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7
usermods/audioreactive/audio_reactive.h
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@ -98,6 +98,7 @@ static float multAgc = 1.0f; // sample * multAgc = sampleAgc.
// FFT Variables
constexpr uint16_t samplesFFT = 512; // Samples in an FFT batch - This value MUST ALWAYS be a power of 2
constexpr uint16_t samplesFFT_2 = 256; // meaningfull part of FFT results - nly the "lower half" contains usefull information.
static float FFT_MajorPeak = 0.0f;
static float FFT_Magnitude = 0.0f;
@ -105,7 +106,7 @@ static float FFT_Magnitude = 0.0f;
// These are the input and output vectors. Input vectors receive computed results from FFT.
static float vReal[samplesFFT];
static float vImag[samplesFFT];
static float fftBin[samplesFFT];
static float fftBin[samplesFFT_2];
#ifdef UM_AUDIOREACTIVE_USE_NEW_FFT
static float windowWeighingFactors[samplesFFT];
@ -231,7 +232,7 @@ void FFTcode(void * parameter)
FFT.MajorPeak(&FFT_MajorPeak, &FFT_Magnitude); // let the effects know which freq was most dominant
#endif
for (int i = 0; i < samplesFFT; i++) { // Values for bins 0 and 1 are WAY too large. Might as well start at 3.
for (int i = 0; i < samplesFFT_2; i++) { // Values for bins 0 and 1 are WAY too large. Might as well start at 3.
float t = fabs(vReal[i]); // just to be sure - values in fft bins should be positive any way
fftBin[i] = t / 16.0f; // Reduce magnitude. Want end result to be linear and ~4096 max.
} // for()
@ -652,7 +653,7 @@ class AudioReactive : public Usermod {
// Poor man's beat detection by seeing if sample > Average + some value.
// if (sample > (sampleAvg + maxVol) && millis() > (timeOfPeak + 200)) {
if ((fftBin[binNum] > maxVol) && (millis() > (timeOfPeak + 100))) { // This goes through ALL of the 255 bins
if ((maxVol > 0) && (binNum > 1) && (fftBin[binNum] > maxVol) && (millis() > (timeOfPeak + 100))) { // This goes through ALL of the 255 bins - but ignores stupid settings
// Then we got a peak, else we don't. The peak has to time out on its own in order to support UDP sound sync.
samplePeak = true;
timeOfPeak = millis();