shithub: sox

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minor change: use periodic window

--- a/src/spectrogram.c

+++ b/src/spectrogram.c

@@ -71,7 +71,7 @@

   int        dft_size, step_size, block_steps, block_num, rows, cols, read;

   int        x_size, end, end_min, last_end;

   sox_bool   truncated;

-  double     buf[MAX_FFT_SIZE], dft_buf[MAX_FFT_SIZE], window[MAX_FFT_SIZE];

+  double     buf[MAX_FFT_SIZE], dft_buf[MAX_FFT_SIZE], window[MAX_FFT_SIZE+1];

   double     block_norm, max, magnitudes[(MAX_FFT_SIZE>>1) + 1];

   float      * dBfs;

 } priv_t;

@@ -170,7 +170,7 @@

 static double make_window(priv_t * p, int end)

 {

   double sum = 0, * w = end < 0? p->window : p->window + end;

-  int i, n = p->dft_size - abs(end);

+  int i, n = 1 + p->dft_size - abs(end);

   if (end) memset(p->window, 0, sizeof(p->window));

   for (i = 0; i < n; ++i) w[i] = 1;

@@ -185,7 +185,7 @@

         (p->dB_range + p->gain) * (1.005 + p->window_adjust / 50) + 6);

   }

   for (i = 0; i < p->dft_size; ++i) sum += p->window[i];

-  for (i = 0; i < p->dft_size; ++i) p->window[i] *= 2 / sum

+  for (--n, i = 0; i < p->dft_size; ++i) p->window[i] *= 2 / sum

     * sqr((double)n / p->dft_size);    /* empirical small window adjustment */

   return sum;

 }