ftc/soundthermo-cpp
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Improved handling of audio subsystem delays

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ftc
2021-01-06 12:13:14 +03:00
parent 2440d0aa3f
commit 0a3947ebf2
6 changed files with 104 additions and 71 deletions
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Measurer.cpp
+29 -11
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@@ -67,22 +67,29 @@ float Measurer::Measure(float duration)
float Measurer::ProcessData(QByteArray data)
{
// convert byte data to sample array
vector<float> samples;
vector<float> read_samples;
// note that we fixed format to be little-endian, two-byte, signed
for (int i = 0; i < data.count(); i += 2)
{
int t = qFromLittleEndian<qint16>(data.data() + i);
samples.push_back(t / 32767.0);
read_samples.push_back(t / 32767.0);
}
if (debug)
{
ostringstream oss;
for (int i = 0; i < (int)samples.size(); i++)
for (int i = 0; i < (int)read_samples.size(); i++)
{
oss << samples[i] << " ";
oss << read_samples[i] << " ";
}
cerr << "Samples read: " << oss.str() << "\n";
}
// cut off some initial samples because of delays in sound subsystem
// (otherwise we can hear some older sound which is not finished playing yet)
vector<float> samples;
for (int i = (int)(read_samples.size() * INITIAL_DELAY_PERCENTAGE); i < (int)read_samples.size(); i++)
{
samples.push_back(read_samples[i]);
}
// determine silence threshold (will consider signal less than SILENCE of maximum as silence)
float max_sample = abs(samples[0]);
for (int i = 1; i < (int)samples.size(); i++)
@@ -109,6 +116,11 @@ float Measurer::ProcessData(QByteArray data)
d[i] = Complex(samples[left_pos + i], 0);
}
FFT(d, pow, false);
return ProcessSpectrum (pow, d);
}
float Measurer::ProcessSpectrum(int pow, Complex *d)
{
if (debug)
{
ostringstream oss;
@@ -119,24 +131,30 @@ float Measurer::ProcessData(QByteArray data)
}
cerr << "Spectrum: " << oss.str() << "\n";
}
// will search for maximum value near our frequency
// also will
float desired = TONE_FREQUENCY * pow / SAMPLE_RATE;
int find_left = (int)((TONE_FREQUENCY - FREQUENCY_GAP) * pow / SAMPLE_RATE);
if (find_left < 0) find_left = 0;
int find_right = (int)((TONE_FREQUENCY + FREQUENCY_GAP) * pow / SAMPLE_RATE);
if (find_right > pow) find_right = pow;
float max = -1;
int argmax = 0;
for (int i = 0; i < pow; i++)
float avg = 0;
for (int i = find_left; i < find_right; i++)
{
float amp = (float)sqrt(d[i].real() * d[i].real() + d[i].imag() * d[i].imag());
if (amp > max)
{
max = amp;
argmax = i;
}
avg += amp;
}
float desired = TONE_FREQUENCY * pow / SAMPLE_RATE;
avg /= (find_right - find_left);
if (debug)
{
cerr << "Measure: desired = " << desired << " argmax = " << argmax << " max = "
<< max << " left_pos = " << left_pos << " right_pos = " << right_pos << "\n";
cerr << "ProcessSpectrum: desired = " << desired << " avg = " << avg << " max = " << max << "\n";
}
if (abs(desired - argmax) < 1e-3)
if (abs(max / avg) - 1 > PEAK_LEVEL)
{
return max / pow;
}