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Adjustments to noise gate, commit to min sampling method

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This commit is contained in:
Philip Rosedale 2014-02-12 22:53:46 -08:00
parent 3a807c1914
commit be7d1a5723
2 changed files with 41 additions and 33 deletions
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70
interface/src/Audio.cpp
View file

@ -37,7 +37,7 @@ static const short JITTER_BUFFER_SAMPLES = JITTER_BUFFER_LENGTH_MSECS * NUM_AUDI
static const float AUDIO_CALLBACK_MSECS = (float) NETWORK_BUFFER_LENGTH_SAMPLES_PER_CHANNEL / (float)SAMPLE_RATE * 1000.0;
static const int NUMBER_OF_NOISE_SAMPLE_FRAMES = 100;
static const int NUMBER_OF_NOISE_SAMPLE_FRAMES = 300;
// Mute icon configration
static const int ICON_SIZE = 24;
@ -67,7 +67,7 @@ Audio::Audio(Oscilloscope* scope, int16_t initialJitterBufferSamples, QObject* p
_measuredJitter(0),
_jitterBufferSamples(initialJitterBufferSamples),
_lastInputLoudness(0),
_averageInputLoudness(0),
_noiseGateMeasuredFloor(0),
_noiseGateSampleCounter(0),
_noiseGateOpen(false),
_noiseGateEnabled(true),
@ -356,58 +356,66 @@ void Audio::handleAudioInput() {
NETWORK_BUFFER_LENGTH_SAMPLES_PER_CHANNEL,
_inputFormat, _desiredInputFormat);
//
// Impose Noise Gate
//
// The Noise Gate is used to reject constant background noise by measuring the noise
// floor observed at the microphone and then opening the 'gate' to allow microphone
// signals to be transmitted when the microphone samples average level exceeds a multiple
// of the noise floor.
//
// NOISE_GATE_HEIGHT: How loud you have to speak relative to noise background to open the gate.
// Make this value lower for more sensitivity and less rejection of noise.
// NOISE_GATE_WIDTH: The number of samples in an audio frame for which the height must be exceeded
// to open the gate.
// NOISE_GATE_CLOSE_FRAME_DELAY: Once the noise is below the gate height for the frame, how many frames
// will we wait before closing the gate.
// NOISE_GATE_FRAMES_TO_AVERAGE: How many audio frames should we average together to compute noise floor.
// More means better rejection but also can reject continuous things like singing.
// NUMBER_OF_NOISE_SAMPLE_FRAMES: How often should we re-evaluate the noise floor?
float loudness = 0;
float thisSample = 0;
int samplesOverNoiseGate = 0;
#define NOISE_MIN_SAMPLE
#ifdef NOISE_MIN_SAMPLE
const float NOISE_GATE_HEIGHT = 12.f;
const float NOISE_GATE_HEIGHT = 7.f;
const int NOISE_GATE_WIDTH = 5;
const int NOISE_GATE_CLOSE_FRAME_DELAY = 5;
#else
const float NOISE_GATE_HEIGHT = 6.f;
const int NOISE_GATE_WIDTH = 5;
const int NOISE_GATE_CLOSE_FRAME_DELAY = 5;
#endif
const int NOISE_GATE_FRAMES_TO_AVERAGE = 5;
for (int i = 0; i < NETWORK_BUFFER_LENGTH_SAMPLES_PER_CHANNEL; i++) {
thisSample = fabsf(monoAudioSamples[i]);
loudness += thisSample;
// Noise Reduction: Count peaks above the average loudness
if (thisSample > (_averageInputLoudness * NOISE_GATE_HEIGHT)) {
if (thisSample > (_noiseGateMeasuredFloor * NOISE_GATE_HEIGHT)) {
samplesOverNoiseGate++;
}
}
_lastInputLoudness = loudness / NETWORK_BUFFER_LENGTH_SAMPLES_PER_CHANNEL;
//qDebug("%.1f", _lastInputLoudness);
#ifdef NOISE_MIN_SAMPLE
float averageOfAllSampleFrames = 0.f;
_noiseSampleFrames[_noiseGateSampleCounter++] = _lastInputLoudness;
if (_noiseGateSampleCounter == NUMBER_OF_NOISE_SAMPLE_FRAMES) {
float smallestSample = MAXFLOAT;
for (int i = 0; i < NUMBER_OF_NOISE_SAMPLE_FRAMES; i++) {
if (_noiseSampleFrames[i] < smallestSample) {
smallestSample = _noiseSampleFrames[i];
for (int i = 0; i <= NUMBER_OF_NOISE_SAMPLE_FRAMES - NOISE_GATE_FRAMES_TO_AVERAGE; i+= NOISE_GATE_FRAMES_TO_AVERAGE) {
float thisAverage = 0.0f;
for (int j = i; j < i + NOISE_GATE_FRAMES_TO_AVERAGE; j++) {
thisAverage += _noiseSampleFrames[j];
averageOfAllSampleFrames += _noiseSampleFrames[j];
}
thisAverage /= NOISE_GATE_FRAMES_TO_AVERAGE;
if (thisAverage < smallestSample) {
smallestSample = thisAverage;
}
}
_averageInputLoudness = smallestSample;
averageOfAllSampleFrames /= NUMBER_OF_NOISE_SAMPLE_FRAMES;
_noiseGateMeasuredFloor = smallestSample;
_noiseGateSampleCounter = 0;
//qDebug("smallest sample = %.1f", _averageInputLoudness);
qDebug("smallest sample = %.1f, avg of all = %.1f", _noiseGateMeasuredFloor, averageOfAllSampleFrames);
}
#else
_noiseGateSampleCounter++;
if (_noiseGateSampleCounter == NUMBER_OF_NOISE_SAMPLE_FRAMES) {
qDebug("average loudness = %.1f", _averageInputLoudness);
_noiseGateSampleCounter = 0;
}
const float LOUDNESS_AVERAGING_FRAMES = 1000.f; // This will be about 10 seconds
_averageInputLoudness = (1.f - 1.f / LOUDNESS_AVERAGING_FRAMES) * _averageInputLoudness + (1.f / LOUDNESS_AVERAGING_FRAMES) * _lastInputLoudness;
#endif
if (_noiseGateEnabled) {
if (samplesOverNoiseGate > NOISE_GATE_WIDTH) {
_noiseGateOpen = true;

4
interface/src/Audio.h
View file

@ -45,7 +45,7 @@ public:
void render(int screenWidth, int screenHeight);
float getLastInputLoudness() const { return glm::max(_lastInputLoudness - _averageInputLoudness, 0.f); }
float getLastInputLoudness() const { return glm::max(_lastInputLoudness - _noiseGateMeasuredFloor, 0.f); }
void setNoiseGateEnabled(bool noiseGateEnabled) { _noiseGateEnabled = noiseGateEnabled; }
@ -109,7 +109,7 @@ private:
float _measuredJitter;
int16_t _jitterBufferSamples;
float _lastInputLoudness;
float _averageInputLoudness;
float _noiseGateMeasuredFloor;
float* _noiseSampleFrames;
int _noiseGateSampleCounter;
bool _noiseGateOpen;