2016-03-15 21:52:31 +00:00
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#include "voiceActivityDetection.h"
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#include <audio/DCOffset.h>
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#include <audio/SampleRateConverter.h>
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#include <boost/optional/optional.hpp>
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#include <logging.h>
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using std::numeric_limits;
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using std::vector;
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using boost::optional;
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float getRMS(AudioStream& audioStream, int maxSampleCount = numeric_limits<int>::max()) {
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double sum = 0;
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int sampleCount;
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for (sampleCount = 0; sampleCount < maxSampleCount && !audioStream.endOfStream(); sampleCount++) {
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sum += std::pow(static_cast<double>(audioStream.readSample()), 2);
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}
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return sampleCount > 0 ? static_cast<float>(std::sqrt(sum / sampleCount)) : 0.0f;
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}
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2016-03-28 18:25:11 +00:00
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vector<TimeRange> detectVoiceActivity(std::unique_ptr<AudioStream> audioStream) {
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2016-03-15 21:52:31 +00:00
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// Make sure audio stream has no DC offset
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audioStream = removeDCOffset(std::move(audioStream));
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// Resample to remove noise
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constexpr int maxFrequency = 1000;
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constexpr int sampleRate = 2 * maxFrequency;
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audioStream = convertSampleRate(std::move(audioStream), sampleRate);
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float rms = getRMS(*audioStream->clone(true));
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float cutoff = rms / 50;
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centiseconds maxGap(10);
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2016-03-28 18:25:11 +00:00
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vector<TimeRange> result;
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2016-03-15 21:52:31 +00:00
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optional<centiseconds> segmentStart, segmentEnd;
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for (centiseconds time = centiseconds(0); !audioStream->endOfStream(); ++time) {
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float currentPower = getRMS(*audioStream, sampleRate / 100);
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bool active = currentPower > cutoff;
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if (active) {
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if (!segmentStart) {
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segmentStart = time;
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}
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segmentEnd = time + centiseconds(1);
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} else if (segmentEnd && time > segmentEnd.value() + maxGap) {
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2016-03-28 18:25:11 +00:00
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result.push_back(TimeRange(segmentStart.value(), segmentEnd.value()));
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2016-03-15 21:52:31 +00:00
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logTimedEvent("utterance", segmentStart.value(), segmentEnd.value(), "");
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segmentStart.reset();
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segmentEnd.reset();
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}
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}
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if (segmentEnd) {
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2016-03-28 18:25:11 +00:00
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result.push_back(TimeRange(segmentStart.value(), segmentEnd.value()));
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2016-03-15 21:52:31 +00:00
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}
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return result;
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}
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