shithub: sox

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improve SNR robustness and cut-off logic

--- a/src/vad.c

+++ b/src/vad.c

@@ -45,7 +45,7 @@

   priv_t * p = (priv_t *)effp->priv;

   int c;

-  p->hp_freq          = 300;

+  p->hp_freq          = 120;

   p->lp_freq          = 12500;

   p->measure_duration = .2;

   p->measure_freq     = 10;

@@ -153,7 +153,7 @@

   priv_t * p = (priv_t *)effp->priv;

   double * buf = p->dft_buf;

   double mult, result = 0;

-  size_t i;

+  size_t i, n;

   for (i = 0; i < p->measure_len; ++i) {

     buf[i] = p->buffer[x] * p->window1[i];

@@ -168,9 +168,10 @@

   memset(buf + i, 0, ((p->dft_len >> 1) - i) * sizeof(*buf));

   lsx_safe_rdft((int)p->dft_len >> 1, 1, buf);

-  i = max(1, (size_t)(.01 * p->dft_len + .5));

-  mult = (p->dft_len / 4 + 1.) / (p->dft_len / 4 - i);

-  for (; i < p->dft_len >> 2; ++i)

+  i = max(1, (size_t)(.006 * p->dft_len + .5));

+  n = (size_t)(.014 * p->dft_len + .5);

+  mult = (p->dft_len / 4 + 1.) / (n - i);

+  for (; i < n; ++i)

     result += sqr(buf[2*i]) + sqr(buf[2*i+1]);

   result = log(mult * result);

   result = max(result + 50, 0);

@@ -227,7 +228,7 @@

               started = sox_true;

             }

           } while (flush < p->search_len && (

-                (meas > meas0 - 12 && (c->slope1 > 4 || c->slope2 > 2)) ||

+                (meas > p->trigger_level - 12 && (c->slope1 > 4 || c->slope2 > 2)) ||

                 meas > p->trigger_level));

           to_flush = range_limit(flush, to_flush, p->search_len);

         }