[FFmpeg-devel] [PATCH] avfilter/colorize: add speed option

[Yannis Gerlach]

The speed option allows to have a constant (per frame) change of hue. 
This allows for an easy way of creating an color changing effect without 
relying on somewhat complicated expressions.

Signed-off-by: Yannis Gerlach <ffmpeg at ygerlach.de>
---
  libavfilter/vf_colorize.c | 17 +++++++++++++----
  1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/libavfilter/vf_colorize.c b/libavfilter/vf_colorize.c
index e6c563e3e2..ad8577c8fd 100644
--- a/libavfilter/vf_colorize.c
+++ b/libavfilter/vf_colorize.c
@@ -29,6 +29,7 @@ typedef struct ColorizeContext {
      float saturation;
      float lightness;
      float mix;
+    float speed;
       int depth;
      int c[3];
@@ -205,6 +206,13 @@ static int filter_frame(AVFilterLink *inlink, 
AVFrame *frame)
      ff_filter_execute(ctx, do_slice, frame, NULL,
                        FFMIN(s->planeheight[1], 
ff_filter_get_nb_threads(ctx)));
  +    s->hue += s->speed;
+    if (s->hue < 0.f) {
+        s->hue += 360.f;
+    } else if(s->hue > 360.f) {
+        s->hue -= 360.f;
+    }
+
      return ff_filter_frame(ctx->outputs[0], frame);
  }
  @@ -263,10 +271,11 @@ static const AVFilterPad colorize_inputs[] = {
  #define VF 
AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
   static const AVOption colorize_options[] = {
-    { "hue",        "set the hue",                     OFFSET(hue), 
    AV_OPT_TYPE_FLOAT, {.dbl=0},  0, 360, VF },
-    { "saturation", "set the saturation", 
OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl=0.5},0,   1, VF },
-    { "lightness",  "set the lightness", 
OFFSET(lightness),  AV_OPT_TYPE_FLOAT, {.dbl=0.5},0,   1, VF },
-    { "mix",        "set the mix of source lightness", OFFSET(mix), 
    AV_OPT_TYPE_FLOAT, {.dbl=1},  0,   1, VF },
+    { "hue",        "set the hue",                     OFFSET(hue), 
    AV_OPT_TYPE_FLOAT, {.dbl=0},    0, 360, VF },
+    { "saturation", "set the saturation", 
OFFSET(saturation), AV_OPT_TYPE_FLOAT, {.dbl=0.5},  0,   1, VF },
+    { "lightness",  "set the lightness", 
OFFSET(lightness),  AV_OPT_TYPE_FLOAT, {.dbl=0.5},  0,   1, VF },
+    { "mix",        "set the mix of source lightness", OFFSET(mix), 
    AV_OPT_TYPE_FLOAT, {.dbl=1},    0,   1, VF },
+    { "speed",      "set the change of hue per frame", OFFSET(speed), 
    AV_OPT_TYPE_FLOAT, {.dbl=0}, -180, 180, VF },
      { NULL }
  };
  -- 2.34.1