vo_opengl: remove cscale-down suboption

For an explanation see the additions to the manpage.

3 files changed, 15 insertions, 9 deletions

diff --git a/DOCS/man/vo.rst b/DOCS/man/vo.rst
index bbca84ecdb..91452c0d57 100644
--- a/DOCS/man/vo.rst
+++ b/DOCS/man/vo.rst
@@ -446,10 +446,16 @@ Available video output drivers are:
         RGB. If chroma is not subsampled, this option is ignored, and the
         luma scaler is used instead. Setting this option is often useless.
 
-    ``lscale-down=<filter>``, ``cscale-down=<filter>``
-        Like ``lscale`` and ``cscale``, but apply these filters on downscaling
+    ``lscale-down=<filter>`
+        Like ``lscale``, but apply these filters on downscaling
         instead. If these options are unset, the filter implied by ``lscale``
-        (and ``cscale``, respectively) will be applied.
+        will be applied.
+
+        There used to be a ``cscale-down`` option. This was removed, because
+        chroma scaling is usually only used for upscaling. The only case where
+        this was actually used for downscaling was when the video was scaled
+        down by more than twice (or other factors, depending on image formats),
+        and ``lscale`` did not use a separable scaler.
 
     ``cparam1``, ``cparam2``, ``cradius``
         Set filter parameters and radius for ``cscale``.
diff --git a/video/out/gl_video.c b/video/out/gl_video.c
index 8f4f7e8cbd..e991c85857 100644
--- a/video/out/gl_video.c
+++ b/video/out/gl_video.c
@@ -361,8 +361,7 @@ const struct m_sub_options gl_video_conf = {
         OPT_FLAG("pbo", pbo, 0),
         OPT_STRING_VALIDATE("lscale", scalers[0], 0, validate_scaler_opt),
         OPT_STRING_VALIDATE("cscale", scalers[1], 0, validate_scaler_opt),
-        OPT_STRING_VALIDATE("lscale-down", dscalers[0], 0, validate_scaler_opt),
-        OPT_STRING_VALIDATE("cscale-down", dscalers[1], 0, validate_scaler_opt),
+        OPT_STRING_VALIDATE("lscale-down", dscaler, 0, validate_scaler_opt),
         OPT_FLOAT("lparam1", scaler_params[0][0], 0),
         OPT_FLOAT("lparam2", scaler_params[0][1], 0),
         OPT_FLOAT("cparam1", scaler_params[1][0], 0),
@@ -407,6 +406,7 @@ const struct m_sub_options gl_video_conf = {
         OPT_COLOR("background", background, 0),
 
         OPT_REMOVED("approx-gamma", "this is always enabled now"),
+        OPT_REMOVED("cscale-down", "use 'indirect' and lscale-down"),
         {0}
     },
     .size = sizeof(struct gl_video_opts),
@@ -1435,8 +1435,8 @@ static const char *expected_scaler(struct gl_video *p, int unit)
     {
         return "bilinear";
     }
-    if (p->opts.dscalers[unit] && get_scale_factor(p) < 1.0)
-        return p->opts.dscalers[unit];
+    if (unit == 0 && p->opts.dscaler && get_scale_factor(p) < 1.0)
+        return p->opts.dscaler;
     return p->opts.scalers[unit];
 }
 
@@ -2609,7 +2609,7 @@ void gl_video_set_options(struct gl_video *p, struct gl_video_opts *opts)
     p->opts = *opts;
     for (int n = 0; n < 2; n++) {
         p->opts.scalers[n] = (char *)handle_scaler_opt(p->opts.scalers[n]);
-        p->opts.dscalers[n] = (char *)handle_scaler_opt(p->opts.dscalers[n]);
+        p->opts.dscaler = (char *)handle_scaler_opt(p->opts.dscaler);
     }
 
     if (!p->opts.gamma && p->video_eq.values[MP_CSP_EQ_GAMMA] != 0)
diff --git a/video/out/gl_video.h b/video/out/gl_video.h
index 37c819ecdb..b3c5d5abe5 100644
--- a/video/out/gl_video.h
+++ b/video/out/gl_video.h
@@ -30,7 +30,7 @@ struct lut3d {
 
 struct gl_video_opts {
     char *scalers[2];
-    char *dscalers[2];
+    char *dscaler;
     float scaler_params[2][2];
     float scaler_radius[2];
     int indirect;