initial implementation of transient detection added

1 files changed, 51 insertions, 0 deletions

diff --git a/src/transient_detector.cpp b/src/transient_detector.cpp
new file mode 100644
index 0000000..49e523d
--- /dev/null
+++ b/src/transient_detector.cpp
@@ -0,0 +1,51 @@
+#include "transient_detector.h"
+#include <stdlib.h>
+
+namespace NAtracDEnc {
+
+static double calculateRMS(const double* in, uint32_t n) {
+    double s = 0;
+    for (uint32_t i = 0; i < n; i++) {
+        s += in[i] * in[i];
+    }
+    s /= n;
+    return sqrt(s);
+}
+
+void TTransientDetector::HPFilter(const double* in, double* out) {
+    const uint32_t firLen = 21;
+    static const double fircoef[] = {
+        -8.65163e-18 * 2.0, -0.00851586 * 2.0, -6.74764e-18 * 2.0, 0.0209036 * 2.0,
+        -3.36639e-17 * 2.0, -0.0438162 * 2.0, -1.54175e-17 * 2.0, 0.0931738 * 2.0,
+        -5.52212e-17 * 2.0, -0.313819 * 2.0
+    };
+    const uint32_t x = prevBufSz;
+    memcpy(HPFBuffer.data() + x, in, BlockSz * sizeof(double));
+    const double* inBuf = HPFBuffer.data();
+    for (int i = 0; i < BlockSz; ++i) {
+        double s = inBuf[i + 10];
+        double s2 = 0;
+        for (int j = 0; j < ((firLen - 1) / 2) - 1 ; j += 2) {
+            s += fircoef[j] * (inBuf[i + j] + inBuf[i + firLen - j]);
+            s2 += fircoef[j + 1] * (inBuf[i + j + 1] + inBuf[i + firLen - j - 1]);
+        }
+        out[i] = (s + s2)/2;
+    }
+    memcpy(HPFBuffer.data(), in + (BlockSz - x),  x * sizeof(double));
+}
+
+
+bool TTransientDetector::Detect(const double* buf) {
+    double* rmsPerShortBlock = reinterpret_cast<double*>(alloca(sizeof(double) * NShortBlocks));
+    std::vector<double> filtered(BlockSz);
+    HPFilter(buf, filtered.data());
+    for (uint32_t i = 0; i < NShortBlocks; ++i) {
+        rmsPerShortBlock[i] = 19.0 * log10(calculateRMS(&filtered[i * ShortSz], ShortSz));
+        if (i && rmsPerShortBlock[i] - rmsPerShortBlock[i - 1] > 10) {
+            return true;
+        }
+    }
+    return false;
+}
+
+}