shithub: sox

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add sloped TPDF

--- a/src/dither.c

+++ b/src/dither.c

@@ -115,16 +115,16 @@

 static const filter_t filters[] = {

   {44100, fir,  5, 210, lip44, Shape_lipshitz},

-  {46000, fir,  9, 270, fwe44, Shape_f_weighted},

+  {46000, fir,  9, 271, fwe44, Shape_f_weighted},

   {46000, fir,  9, 159, mew44, Shape_modified_e_weighted},

   {46000, fir,  9, 320, iew44, Shape_improved_e_weighted},

   {48000, iir,  4, 220, ges48, Shape_gesemann},

-  {44100, iir,  4, 228, ges44, Shape_gesemann},

+  {44100, iir,  4, 229, ges44, Shape_gesemann},

   {48000, fir, 16, 300, shi48, Shape_shibata},

   {44100, fir, 20, 330, shi44, Shape_shibata},

-  {37800, fir, 16, 238, shi38, Shape_shibata},

-  {48000, fir, 16, 245, shl48, Shape_low_shibata},

-  {44100, fir, 15, 246, shl44, Shape_low_shibata},

+  {37800, fir, 16, 240, shi38, Shape_shibata},

+  {48000, fir, 16, 249, shl48, Shape_low_shibata},

+  {44100, fir, 15, 247, shl44, Shape_low_shibata},

   {44100, fir, 20, 382, shh44, Shape_high_shibata},

   {    0, fir,  0,   0,  NULL, Shape_none},

 };

@@ -133,13 +133,13 @@

 typedef struct {

   filter_name_t filter_name;

-  sox_bool      auto_detect;

+  sox_bool      auto_detect, alt_tpdf;

   double        dummy;

   double        previous_errors[MAX_N * 2];

   double        previous_outputs[MAX_N * 2];

   size_t        pos, prec, num_output;

-  int32_t       history, ranqd1;

+  int32_t       history, ranqd1, r;

   double const  * coefs;

   sox_bool      dither_off;

   int           (*flow)(sox_effect_t *, const sox_sample_t *, sox_sample_t *, size_t *, size_t *);

@@ -178,13 +178,13 @@

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

   size_t len = *isamp = *osamp = min(*isamp, *osamp);

-  if (p->auto_detect) while (len--) {

-    p->history = ((p->history << 1) + !!(*ibuf & (-1u >> p->prec)));

-    if (p->history) {

-      int32_t r1 = RANQD1 >> p->prec, r2 = RANQD1 >> p->prec;

-      double d = ((double)*ibuf++ + r1 + r2) / (1 << (32 - p->prec));

+  while (len--) {

+    if (!p->auto_detect || (p->history = ((p->history << 1) + !!(*ibuf & (-1u >> p->prec))))) {

+      int32_t r = RANQD1 >> p->prec;

+      double d = ((double)*ibuf++ + r + (p->alt_tpdf? -p->r : (RANQD1 >> p->prec))) / (1 << (32 - p->prec));

       int i = d < 0? d - .5 : d + .5;

-      if (i < (-1 << (p->prec-1)))

+      p->r = r;

+      if (i <= (-1 << (p->prec-1)))

         ++effp->clips, *obuf = SOX_SAMPLE_MIN;

       else if (i > (int)SOX_INT_MAX(p->prec))

         ++effp->clips, *obuf = SOX_INT_MAX(p->prec) << (32 - p->prec);

@@ -202,17 +202,6 @@

     }

     ++p->num_output;

   }

-  else while (len--) {

-    int32_t r1 = RANQD1 >> p->prec, r2 = RANQD1 >> p->prec;

-    double d = ((double)*ibuf++ + r1 + r2) / (1 << (32 - p->prec));

-    int i = d < 0? d - .5 : d + .5;

-    if (i <= (-1 << (p->prec-1)))

-      ++effp->clips, *obuf = SOX_SAMPLE_MIN;

-    else if (i > (int)SOX_INT_MAX(p->prec))

-      ++effp->clips, *obuf = SOX_INT_MAX(p->prec) << (32 - p->prec);

-    else *obuf = i << (32 - p->prec);

-    ++obuf;

-  }

   return SOX_SUCCESS;

 }

@@ -221,8 +210,9 @@

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

   int c;

-  while ((c = getopt(argc, argv, "+asf:""rt")) != -1) switch (c) {

+  while ((c = getopt(argc, argv, "+aSsf:""rt")) != -1) switch (c) {

     case 'a': p->auto_detect = sox_true; break;

+    case 'S': p->alt_tpdf = sox_true; break;

     case 'r': case 't': break; /* No longer in use */

     case 's': p->filter_name = Shape_shibata; break;

     case 'f':

@@ -253,7 +243,10 @@

     for (f = filters; f->len && (f->name != p->filter_name || fabs(effp->in_signal.rate - f->rate) / f->rate > .05); ++f); /* 5% leeway on frequency */

     if (!f->len) {

-      lsx_warn("no `%s' filter is available for rate %g; using plain TPDF", lsx_find_enum_value(p->filter_name, filter_names)->text, effp->in_signal.rate);

+      p->alt_tpdf |= effp->in_signal.rate >= 22050;

+      lsx_warn("no `%s' filter is available for rate %g; using %s TPDF",

+          lsx_find_enum_value(p->filter_name, filter_names)->text,

+          effp->in_signal.rate, p->alt_tpdf? "sloped" : "plain");

     }

     else {

       assert(f->len <= MAX_N);

@@ -289,8 +282,10 @@

 sox_effect_handler_t const * lsx_dither_effect_fn(void)

 {

   static sox_effect_handler_t handler = {

-    "dither", "[-a] [-s|-f filter]"

+    "dither", "[-a] [-S|-s|-f filter]"

+    "\n  (none)   Use TPDF"

     "\n  -a       Automatically turn on & off dithering as needed (use with caution!)"

+    "\n  -S       Use sloped TPDF (without noise shaping)"

     "\n  -s       Shape noise (with shibata filter)"

     "\n  -f name  Set shaping filter to one of: lipshitz, f-weighted,"

     "\n           modified-e-weighted, improved-e-weighted, gesemann,"