avfilter/af_afftdn: expose floor offset factor option

doc/filters.texi

@@ -1319,7 +1319,7 @@ Set the residual floor in dB, allowed range is -80 to -20.
 Default value is -38 dB.
 
 @item track_noise, tn
-Enable noise tracking. By default is disabled.
+Enable noise floor tracking. By default is disabled.
 With this enabled, noise floor is automatically adjusted.
 
 @item track_residual, tr
@@ -1348,6 +1348,11 @@ each frequency bin. Value @var{0} enables instant adaptation, while higher value
 react much slower.
 Allowed range is from @var{0} to @var{1}. Default value is @var{0.5}.
 
+@item floor_offset, fo
+Set the noise floor offset factor. This option is used to adjust offset applied to measured
+noise floor. It is only effective when noise floor tracking is enabled.
+Allowed range is from @var{-2.0} to @var{2.0}. Default value is @var{1.0}.
+
 @item noise_link, nl
 Set the noise link used for multichannel audio.
 

libavfilter/af_afftdn.c

@@ -117,6 +117,7 @@ typedef struct AudioFFTDeNoiseContext {
     int     noise_floor_link;
     float   ratio;
     float   band_multiplier;
+    float   floor_offset;
 
     float   last_residual_floor;
     float   last_noise_floor;
@@ -196,6 +197,8 @@ static const AVOption afftdn_options[] = {
     {  "n", "noise",                      0,                       AV_OPT_TYPE_CONST,  {.i64 = NOISE_MODE},    0,  0, AFR, "mode" },
     { "adaptivity", "set adaptivity factor",OFFSET(ratio),         AV_OPT_TYPE_FLOAT,  {.dbl = 0.5},           0,  1, AFR },
     { "ad",         "set adaptivity factor",OFFSET(ratio),         AV_OPT_TYPE_FLOAT,  {.dbl = 0.5},           0,  1, AFR },
+    { "floor_offset", "set noise floor offset factor",OFFSET(floor_offset), AV_OPT_TYPE_FLOAT, {.dbl = 1.0},  -2,  2, AFR },
+    { "fo",           "set noise floor offset factor",OFFSET(floor_offset), AV_OPT_TYPE_FLOAT, {.dbl = 1.0},  -2,  2, AFR },
     { "noise_link", "set the noise floor link",OFFSET(noise_floor_link),AV_OPT_TYPE_INT,{.i64 = MIN_LINK},     0,  NB_LINK-1, AFR, "link" },
     { "nl", "set the noise floor link",        OFFSET(noise_floor_link),AV_OPT_TYPE_INT,{.i64 = MIN_LINK},     0,  NB_LINK-1, AFR, "link" },
     {  "none",    "none",                 0,                       AV_OPT_TYPE_CONST,  {.i64 = NONE_LINK},     0,  0, AFR, "link" },
@@ -381,11 +384,11 @@ static void process_frame(AVFilterContext *ctx,
 
         flatness = num / den;
         if (flatness > 0.8) {
-            const double offset = floor_offset(noisy_data, s->bin_count, den);
+            const double offset = s->floor_offset * floor_offset(noisy_data, s->bin_count, den);
             const double new_floor = av_clipd(10.0 * log10(den) - 100.0 + offset, -90., -20.);
 
             dnch->noise_floor = 0.1 * new_floor + dnch->noise_floor * 0.9;
-            set_parameters(s, dnch, 1, 0);
+            set_parameters(s, dnch, 1, 1);
         }
     }