[FFmpeg-devel] [PATCH] avfilter/avf_showwaves: add draw grid support

[Paul B Mahol]

Signed-off-by: Paul B Mahol <onemda at gmail.com>
---
 doc/filters.texi            |  6 ++++++
 libavfilter/avf_showwaves.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/doc/filters.texi b/doc/filters.texi
index 62f633c6f8..9c98f1684b 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -19178,6 +19178,12 @@ Cubic root.
 @end table
 
 Default is linear.
+
+ at item grid
+Draw grid, default is disabled.
+
+ at item grid_color
+Set grid color.
 @end table
 
 @subsection Examples
diff --git a/libavfilter/avf_showwaves.c b/libavfilter/avf_showwaves.c
index 0866967984..74d4886cd4 100644
--- a/libavfilter/avf_showwaves.c
+++ b/libavfilter/avf_showwaves.c
@@ -69,6 +69,8 @@ typedef struct ShowWavesContext {
     int mode;                   ///< ShowWavesMode
     int scale;                  ///< ShowWavesScale
     int split_channels;
+    int grid;
+    uint8_t grid_rgba[4];
     uint8_t *fg;
 
     int (*get_h)(int16_t sample, int height);
@@ -104,6 +106,8 @@ static const AVOption showwaves_options[] = {
         { "log", "logarithmic",    0, AV_OPT_TYPE_CONST, {.i64=SCALE_LOG}, .flags=FLAGS, .unit="scale"},
         { "sqrt", "square root",   0, AV_OPT_TYPE_CONST, {.i64=SCALE_SQRT}, .flags=FLAGS, .unit="scale"},
         { "cbrt", "cubic root",    0, AV_OPT_TYPE_CONST, {.i64=SCALE_CBRT}, .flags=FLAGS, .unit="scale"},
+    { "grid", "draw grid", OFFSET(grid), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
+    { "grid_color", "set grid color", OFFSET(grid_rgba), AV_OPT_TYPE_COLOR, {.str="0x333300"}, 0, 0, FLAGS },
     { NULL }
 };
 
@@ -562,6 +566,30 @@ static int alloc_out_frame(ShowWavesContext *showwaves, const int16_t *p,
                                           outlink->time_base);
         for (j = 0; j < outlink->h; j++)
             memset(out->data[0] + j*out->linesize[0], 0, outlink->w * showwaves->pixstep);
+
+        if (showwaves->grid) {
+            const int pixstep = showwaves->pixstep;
+            int ystep = showwaves->split_channels ? outlink->h / inlink->channels / 4 : outlink->h / 4;
+            int channels = showwaves->split_channels ? inlink->channels : 1;
+            int x, s, c, yskip = 0;
+
+            for (c = 0; c < channels; c++) {
+                for (j = 0; j < 4; j++) {
+                    for (x = 0; x < outlink->w; x+=3) {
+                        for (s = 0; s < pixstep; s++) {
+                            out->data[0][(yskip + j * ystep) * out->linesize[0] + x * pixstep + s] = showwaves->grid_rgba[s];
+                        }
+                    }
+                }
+                for (x = 0; x < outlink->w; x+=3) {
+                    for (s = 0; s < pixstep; s++) {
+                        out->data[0][(yskip + j * ystep - 1) * out->linesize[0] + x * pixstep + s] = showwaves->grid_rgba[s];
+                    }
+                }
+
+                yskip += j * ystep;
+            }
+        }
     }
     return 0;
 }
-- 
2.11.0