avfilter/vf_vectorscope: make it possible to override colorspace

Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -12656,6 +12656,15 @@ Values higher than this value will be ignored. Default is 1.
 Note this value is multiplied with actual max possible value one pixel component
 can have. So for 8-bit input and high threshold value of 0.9 actual threshold
 is 0.9 * 255 = 230.
+
+@item colorspace, c
+Set what kind of colorspace to use when drawing graticule.
+@table @samp
+@item auto
+@item 601
+@item 709
+@end table
+Default is auto.
 @end table
 
 @anchor{vidstabdetect}

libavfilter/vf_vectorscope.c

@@ -62,6 +62,7 @@ typedef struct VectorscopeContext {
     int tmin;
     int tmax;
     int flags;
+    int colorspace;
     int cs;
     uint8_t peak[4096][4096];
 
@@ -111,6 +112,11 @@ static const AVOption vectorscope_options[] = {
     { "l",          "set low threshold",  OFFSET(lthreshold), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0, 1, FLAGS},
     { "hthreshold", "set high threshold", OFFSET(hthreshold), AV_OPT_TYPE_FLOAT, {.dbl=1}, 0, 1, FLAGS},
     { "h",          "set high threshold", OFFSET(hthreshold), AV_OPT_TYPE_FLOAT, {.dbl=1}, 0, 1, FLAGS},
+    { "colorspace", "set colorspace", OFFSET(colorspace), AV_OPT_TYPE_INT, {.i64=0}, 0, 2, FLAGS, "colorspace"},
+    { "c",          "set colorspace", OFFSET(colorspace), AV_OPT_TYPE_INT, {.i64=0}, 0, 2, FLAGS, "colorspace"},
+    {   "auto",       0, 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "colorspace" },
+    {   "601",        0, 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "colorspace" },
+    {   "709",        0, 0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, FLAGS, "colorspace" },
     { NULL }
 };
 
@@ -1190,6 +1196,9 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
     AVFilterLink *outlink = ctx->outputs[0];
     AVFrame *out;
 
+    if (s->colorspace) {
+        s->cs = (s->depth - 8) * 2 + s->colorspace - 1;
+    } else {
         switch (av_frame_get_colorspace(in)) {
         case AVCOL_SPC_SMPTE170M:
         case AVCOL_SPC_BT470BG:
@@ -1199,6 +1208,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         default:
             s->cs = (s->depth - 8) * 2 + 1;
         }
+    }
 
     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
     if (!out) {