stdin

stdin.txt

diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
index 21c9561..9f67be2 100644
--- a/libavfilter/avf_showspectrum.c
+++ b/libavfilter/avf_showspectrum.c
@@ -39,6 +39,7 @@ typedef struct {
     int req_fullfilled;
     int nb_display_channels;
     int compat;                 ///< use old up to 2 channels display mode
+    int combined;               ///< use old-style combined channel display mode
     int sliding;                ///< 1 if sliding mode, 0 otherwise
     int xpos;                   ///< x position (current column)
     RDFTContext *rdft;          ///< Real Discrete Fourier Transform context
@@ -57,6 +58,7 @@ static const AVOption showspectrum_options[] = {
     { "s",    "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str = "640x480"}, 0, 0, FLAGS },
     { "slide", "set sliding mode", OFFSET(sliding), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
     { "compat", "set compat mode", OFFSET(compat), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
+    { "combined", "set combined mode", OFFSET(combined), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, FLAGS },
     { NULL },
 };
 
@@ -133,7 +135,7 @@ static int config_output(AVFilterLink *outlink)
     outlink->w = showspectrum->w;
     outlink->h = showspectrum->h;
 
-    h = showspectrum->compat ? outlink->h: outlink->h / inlink->channels;
+    h = showspectrum->compat ? outlink->h : showspectrum->combined ? outlink->h : outlink->h / inlink->channels;
 
     /* RDFT window size (precision) according to the requested output frame height */
     for (rdft_bits = 1; 1 << rdft_bits < 2 * h; rdft_bits++);
@@ -290,12 +292,13 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFilterBufferRef *insampl
             p[2] = (a + b) / 2;
         }
         } else {
-            int h = outlink->h / showspectrum->nb_display_channels;
+            int h = showspectrum->combined ? outlink->h : outlink->h / showspectrum->nb_display_channels;
 
-            for (ch = 0; ch < showspectrum->nb_display_channels; ch++) {
-                for (y = 0; y < h; y++) {
+            for (y = 0; y < h; y++) {
+                for (ch = 0; ch < showspectrum->nb_display_channels; ch++) {
+                    int row = showspectrum->combined ? y : ch * h + y;
                     uint8_t *p = outpicref->data[0] +
-                                 (outlink->h - (ch * h + y) - 1) *
+                                 (outlink->h - row - 1) *
                                  outpicref->linesize[0];
                     int a = sqrt(w * MAGNITUDE(RE(ch), IM(ch)));
 
@@ -306,7 +309,21 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFilterBufferRef *insampl
                         p += showspectrum->xpos * 3;
                     }
 
-                    p[0] = p[1] = p[2] = a;
+                    {
+                        int r = (a/2) * (1 + sin((2 * M_PI * ch) / showspectrum->nb_display_channels));
+                        int g = (a/2) * (1 + sin((2 * M_PI * ch) / showspectrum->nb_display_channels + 2 * M_PI / 3));
+                        int b = (a/2) * (1 + sin((2 * M_PI * ch) / showspectrum->nb_display_channels + 4 * M_PI / 3));
+
+                        if (ch == 0 || !showspectrum->combined) {
+                            p[0] = r;
+                            p[1] = g;
+                            p[2] = b;
+                        } else {
+                            p[0] += r;
+                            p[1] += g;
+                            p[2] += b;
+                        }
+                    }
                 }
             }
         }