shithub: sox

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add Dolph window for spectrogram effect

--- a/ChangeLog

+++ b/ChangeLog

@@ -29,6 +29,7 @@

   o 'Deemph' can now also be used at 48kHz sample rate.  (robs)

   o 'Rate' now much faster in many cases.  (robs)

   o Allow sending spectrograms to stdout. (Ulrich Klauer)

+  o Allow use of Dolph window with spectrograms. (robs)

   o Allow mixing time and sample-count arguments for the delay

     effect, and for spectrogram -S and -d. (Ulrich Klauer)

   o Support multi-channel LADSPA plugins. (Eric Wong)

--- a/sox.1

+++ b/sox.1

@@ -3239,7 +3239,7 @@

 colours to use inside the Z-axis range; two colours are reserved to

 represent out-of-range values.

 .IP \fB\-w\ \fIname\fR

-Window: Hann (default), Hamming, Bartlett, Rectangular or Kaiser.  The

+Window: Hann (default), Hamming, Bartlett, Rectangular, Kaiser or Dolph.  The

 spectrogram is produced using the Discrete Fourier Transform (DFT)

 algorithm.  A significant parameter to this algorithm is the choice of

 `window function'.  By default, SoX uses the Hann window which has good

@@ -3246,10 +3246,10 @@

 all-round frequency-resolution and dynamic-range properties.  For better

 frequency resolution (but lower dynamic-range), select a Hamming window;

 for higher dynamic-range (but poorer frequency-resolution), select a

-Kaiser window.  Bartlett and Rectangular windows are also available.

+Dolph window.  Kaiser, Bartlett and Rectangular windows are also available.

 .IP \fB\-W\ \fInum\fR

 Window adjustment parameter.  This can be used to make small

-adjustments to the Kaiser window shape.  A positive number (up to

+adjustments to the Kaiser or Dolph window shape.  A positive number (up to

 ten) increases its dynamic range, a negative number decreases it.

 .IP \fB\-s\fR

 Allow slack overlapping of DFT windows.

--- a/src/effects_i_dsp.c

+++ b/src/effects_i_dsp.c

@@ -341,6 +341,18 @@

   }

 }

+void lsx_apply_dolph(double h[], const int N, double att)

+{

+  double b = cosh(acosh(pow(10., att / 20)) / (N - 1)), sum, t, v, c, norm = 0;

+  int i, j;

+  for (c = 1 - 1 / (b * b), i = (N - 1) / 2; i >= 0; --i) {

+    for (sum = !i, b=v=t=j=1; j <= i && sum != t; b = b * (i - j) * (1./j), ++j)

+      t = sum, sum += b * (v *= c * (N - i - j) * (1./j));

+    sum /= (N - 1 - i), sum /= (norm = norm? norm : sum);

+    h[i] *= sum, h[N - 1 - i] *= sum;

+  }

+}

+

 double * lsx_make_lpf(int num_taps, double Fc, double beta, double rho,

     double scale, sox_bool dc_norm)

 {

--- a/src/sox_i.h

+++ b/src/sox_i.h

@@ -102,6 +102,7 @@

 void lsx_apply_blackman_nutall(double h[], const int num_points);

 double lsx_kaiser_beta(double att, double tr_bw);

 void lsx_apply_kaiser(double h[], const int num_points, double beta);

+void lsx_apply_dolph(double h[], const int num_points, double att);

 double * lsx_make_lpf(int num_taps, double Fc, double beta, double rho,

     double scale, sox_bool dc_norm);

 void lsx_kaiser_params(double att, double Fc, double tr_bw, double * beta, int * num_taps);

--- a/src/spectrogram.c

+++ b/src/spectrogram.c

@@ -41,7 +41,7 @@

 #define MAX_X_SIZE 200000

-typedef enum {Window_Hann, Window_Hamming, Window_Bartlett, Window_Rectangular, Window_Kaiser} win_type_t;

+typedef enum {Window_Hann, Window_Hamming, Window_Bartlett, Window_Rectangular, Window_Kaiser, Window_Dolph} win_type_t;

 static lsx_enum_item const window_options[] = {

   LSX_ENUM_ITEM(Window_,Hann)

   LSX_ENUM_ITEM(Window_,Hamming)

@@ -48,6 +48,7 @@

   LSX_ENUM_ITEM(Window_,Bartlett)

   LSX_ENUM_ITEM(Window_,Rectangular)

   LSX_ENUM_ITEM(Window_,Kaiser)

+  LSX_ENUM_ITEM(Window_,Dolph)

   {0, 0}};

 typedef struct {

@@ -178,8 +179,10 @@

     case Window_Hamming: lsx_apply_hamming(w, n); break;

     case Window_Bartlett: lsx_apply_bartlett(w, n); break;

     case Window_Rectangular: break;

-    default: lsx_apply_kaiser(w, n, lsx_kaiser_beta(

-        (p->dB_range + p->gain) * (1.1 + p->window_adjust / 50), .1));

+    case Window_Kaiser: lsx_apply_kaiser(w, n, lsx_kaiser_beta(

+        (p->dB_range + p->gain) * (1.1 + p->window_adjust / 50), .1)); break;

+    default: lsx_apply_dolph(w, n,

+        (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

@@ -673,8 +676,8 @@

     "\t-z num\tZ-axis range in dB; default 120",

     "\t-Z num\tZ-axis maximum in dBFS; default 0",

     "\t-q num\tZ-axis quantisation (0 - 249); default 249",

-    "\t-w name\tWindow: Hann (default), Hamming, Bartlett, Rectangular, Kaiser",

-    "\t-W num\tWindow adjust parameter (-10 - 10); applies only to Kaiser",

+    "\t-w name\tWindow: Hann(default)/Hamming/Bartlett/Rectangular/Kaiser/Dolph",

+    "\t-W num\tWindow adjust parameter (-10 - 10); applies only to Kaiser/Dolph",

     "\t-s\tSlack overlap of windows",

     "\t-a\tSuppress axis lines",

     "\t-r\tRaw spectrogram; no axes or legends",