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Detect clipping prior to echo cancellation (overload of the uncancelled raw input will cause echo leakage!)

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This commit is contained in:
Ken Cooke 2019-08-05 10:34:03 -07:00
parent 7322ad78f5
commit ccfe6bda63
1 changed files with 27 additions and 25 deletions
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52
libraries/audio-client/src/AudioClient.cpp
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@ -170,27 +170,21 @@ static void channelDownmix(int16_t* source, int16_t* dest, int numSamples) {
} }
} }
static float computeLoudness(int16_t* samples, int numSamples, int numChannels, bool& isClipping) { static bool detectClipping(int16_t* samples, int numSamples, int numChannels) {
const int32_t CLIPPING_THRESHOLD = 32392; // -0.1 dBFS const int32_t CLIPPING_THRESHOLD = 32392; // -0.1 dBFS
const int32_t CLIPPING_DETECTION = 3; // consecutive samples over threshold const int CLIPPING_DETECTION = 3; // consecutive samples over threshold
float scale = numSamples ? 1.0f / numSamples : 0.0f; bool isClipping = false;
int32_t loudness = 0;
isClipping = false;
if (numChannels == 2) { if (numChannels == 2) {
int32_t oversLeft = 0; int oversLeft = 0;
int32_t oversRight = 0; int oversRight = 0;
for (int i = 0; i < numSamples/2; i++) { for (int i = 0; i < numSamples/2; i++) {
int32_t left = std::abs((int32_t)samples[2*i+0]); int32_t left = std::abs((int32_t)samples[2*i+0]);
int32_t right = std::abs((int32_t)samples[2*i+1]); int32_t right = std::abs((int32_t)samples[2*i+1]);
loudness += left;
loudness += right;
if (left > CLIPPING_THRESHOLD) { if (left > CLIPPING_THRESHOLD) {
isClipping |= (++oversLeft >= CLIPPING_DETECTION); isClipping |= (++oversLeft >= CLIPPING_DETECTION);
} else { } else {
@ -203,13 +197,11 @@ static float computeLoudness(int16_t* samples, int numSamples, int numChannels,
} }
} }
} else { } else {
int32_t overs = 0; int overs = 0;
for (int i = 0; i < numSamples; i++) { for (int i = 0; i < numSamples; i++) {
int32_t sample = std::abs((int32_t)samples[i]); int32_t sample = std::abs((int32_t)samples[i]);
loudness += sample;
if (sample > CLIPPING_THRESHOLD) { if (sample > CLIPPING_THRESHOLD) {
isClipping |= (++overs >= CLIPPING_DETECTION); isClipping |= (++overs >= CLIPPING_DETECTION);
} else { } else {
@ -218,6 +210,17 @@ static float computeLoudness(int16_t* samples, int numSamples, int numChannels,
} }
} }
return isClipping;
}
static float computeLoudness(int16_t* samples, int numSamples) {
float scale = numSamples ? 1.0f / numSamples : 0.0f;
int32_t loudness = 0;
for (int i = 0; i < numSamples; i++) {
loudness += std::abs((int32_t)samples[i]);
}
return (float)loudness * scale; return (float)loudness * scale;
} }
@ -1393,6 +1396,15 @@ void AudioClient::handleMicAudioInput() {
_inputRingBuffer.readSamples(inputAudioSamples.get(), inputSamplesRequired); _inputRingBuffer.readSamples(inputAudioSamples.get(), inputSamplesRequired);
// detect clipping on the raw input
bool isClipping = detectClipping(inputAudioSamples.get(), inputSamplesRequired, _inputFormat.channelCount());
if (isClipping) {
_timeSinceLastClip = 0.0f;
} else if (_timeSinceLastClip >= 0.0f) {
_timeSinceLastClip += AudioConstants::NETWORK_FRAME_SECS;
}
isClipping = (_timeSinceLastClip >= 0.0f) && (_timeSinceLastClip < 2.0f); // 2 second hold time
#if defined(WEBRTC_ENABLED) #if defined(WEBRTC_ENABLED)
if (_isAECEnabled) { if (_isAECEnabled) {
processWebrtcNearEnd(inputAudioSamples.get(), inputSamplesRequired / _inputFormat.channelCount(), processWebrtcNearEnd(inputAudioSamples.get(), inputSamplesRequired / _inputFormat.channelCount(),
@ -1400,9 +1412,7 @@ void AudioClient::handleMicAudioInput() {
} }
#endif #endif
// detect loudness and clipping on the raw input float loudness = computeLoudness(inputAudioSamples.get(), inputSamplesRequired);
bool isClipping = false;
float loudness = computeLoudness(inputAudioSamples.get(), inputSamplesRequired, _inputFormat.channelCount(), isClipping);
_lastRawInputLoudness = loudness; _lastRawInputLoudness = loudness;
// envelope detection // envelope detection
@ -1410,14 +1420,6 @@ void AudioClient::handleMicAudioInput() {
loudness += tc * (_lastSmoothedRawInputLoudness - loudness); loudness += tc * (_lastSmoothedRawInputLoudness - loudness);
_lastSmoothedRawInputLoudness = loudness; _lastSmoothedRawInputLoudness = loudness;
// clipping indicator
if (isClipping) {
_timeSinceLastClip = 0.0f;
} else if (_timeSinceLastClip >= 0.0f) {
_timeSinceLastClip += AudioConstants::NETWORK_FRAME_SECS;
}
isClipping = (_timeSinceLastClip >= 0.0f) && (_timeSinceLastClip < 2.0f); // 2 second hold time
emit inputLoudnessChanged(_lastSmoothedRawInputLoudness, isClipping); emit inputLoudnessChanged(_lastSmoothedRawInputLoudness, isClipping);
if (!_muted) { if (!_muted) {