[FFmpeg-cvslog] avfilter/avf_showcwt: add fm frequency scaler

[Paul B Mahol]

ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sat Nov 11 00:44:36 2023 +0100| [49719d3cb58c03bc0a976f47d2c82e8ca48d1b3d] | committer: Paul B Mahol

avfilter/avf_showcwt: add fm frequency scaler

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=49719d3cb58c03bc0a976f47d2c82e8ca48d1b3d
---

 doc/filters.texi          |  1 +
 libavfilter/avf_showcwt.c | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 12113d7802..13c18a2574 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -30842,6 +30842,7 @@ Set the frequency scale used. Allowed values are:
 @item sqrt
 @item cbrt
 @item qdrt
+ at item fm
 @end table
 Default value is @code{linear}.
 
diff --git a/libavfilter/avf_showcwt.c b/libavfilter/avf_showcwt.c
index d5bc920a4b..e7164ebb25 100644
--- a/libavfilter/avf_showcwt.c
+++ b/libavfilter/avf_showcwt.c
@@ -45,6 +45,7 @@ enum FrequencyScale {
     FSCALE_SQRT,
     FSCALE_CBRT,
     FSCALE_QDRT,
+    FSCALE_FM,
     NB_FSCALE
 };
 
@@ -144,6 +145,7 @@ static const AVOption showcwt_options[] = {
     {  "sqrt",    "sqrt",             0,                       AV_OPT_TYPE_CONST,{.i64=FSCALE_SQRT},   0, 0, FLAGS, "scale" },
     {  "cbrt",    "cbrt",             0,                       AV_OPT_TYPE_CONST,{.i64=FSCALE_CBRT},   0, 0, FLAGS, "scale" },
     {  "qdrt",    "qdrt",             0,                       AV_OPT_TYPE_CONST,{.i64=FSCALE_QDRT},   0, 0, FLAGS, "scale" },
+    {  "fm",      "fm",               0,                       AV_OPT_TYPE_CONST,{.i64=FSCALE_FM},     0, 0, FLAGS, "scale" },
     { "iscale", "set intensity scale", OFFSET(intensity_scale),AV_OPT_TYPE_INT,  {.i64=0},   0, NB_ISCALE-1, FLAGS, "iscale" },
     {  "linear",  "linear",           0,                       AV_OPT_TYPE_CONST,{.i64=ISCALE_LINEAR}, 0, 0, FLAGS, "iscale" },
     {  "log",     "logarithmic",      0,                       AV_OPT_TYPE_CONST,{.i64=ISCALE_LOG},    0, 0, FLAGS, "iscale" },
@@ -292,6 +294,10 @@ static float frequency_band(float *frequency_band,
             frequency = frequency * frequency * frequency * frequency;
             frequency_derivative *= 4.f * powf(frequency, 3.f / 4.f);
             break;
+        case FSCALE_FM:
+            frequency = 2.f * powf(frequency, 3.f / 2.f) / 3.f;
+            frequency_derivative *= sqrtf(frequency);
+            break;
         }
 
         frequency_band[y*2  ] = frequency;
@@ -788,7 +794,8 @@ static int config_output(AVFilterLink *outlink)
     AVFilterContext *ctx = outlink->src;
     AVFilterLink *inlink = ctx->inputs[0];
     ShowCWTContext *s = ctx->priv;
-    float maximum_frequency = fminf(s->maximum_frequency, inlink->sample_rate * 0.5f);
+    const float limit_frequency = inlink->sample_rate * 0.5f;
+    float maximum_frequency = fminf(s->maximum_frequency, limit_frequency);
     float minimum_frequency = s->minimum_frequency;
     float scale = 1.f, factor;
     int ret;
@@ -847,6 +854,10 @@ static int config_output(AVFilterLink *outlink)
         minimum_frequency = powf(minimum_frequency, 0.25f);
         maximum_frequency = powf(maximum_frequency, 0.25f);
         break;
+    case FSCALE_FM:
+        minimum_frequency = powf(9.f * (minimum_frequency * minimum_frequency) / 4.f, 1.f / 3.f);
+        maximum_frequency = powf(9.f * (maximum_frequency * maximum_frequency) / 4.f, 1.f / 3.f);
+        break;
     }
 
     s->frequency_band = av_calloc(s->frequency_band_count,