gl_video: use choice option type for dither-depth suboption

Replaces the numeric magic values -1 and 0 with "no" and "auto". The
numeric values are still allowed for compatibility.

3 files changed, 14 insertions, 13 deletions

diff --git a/DOCS/man/en/vo.rst b/DOCS/man/en/vo.rst
index f3336afef6..6d64e3062e 100644
--- a/DOCS/man/en/vo.rst
+++ b/DOCS/man/en/vo.rst
@@ -319,12 +319,12 @@ opengl
         Enable use of PBOs. This is faster, but can sometimes lead to
         sporadic and temporary image corruption.
 
-    dither-depth=<n>
-        Positive non-zero values select the target bit depth. Default: 0.
+    dither-depth=<N|no|auto>
+        Set dither target depth to N. Default: auto.
 
-        \-1
+        no
             Disable any dithering done by mpv.
-        0
+        auto
             Automatic selection. If output bit depth can't be detected,
             8 bits per component are assumed.
         8
@@ -444,10 +444,10 @@ opengl-hq
 
     This is equivalent to:
 
-    | --vo=opengl:lscale=lanczos2:dither-depth=0:pbo:fbo-format=rgb16
+    | --vo=opengl:lscale=lanczos2:dither-depth=auto:pbo:fbo-format=rgb16
 
     Note that some cheaper LCDs do dithering that gravely interferes with
-    vo_opengl's dithering. Disabling dithering with ``dither-depth=-1`` helps.
+    vo_opengl's dithering. Disabling dithering with ``dither-depth=no`` helps.
 
     Unlike ``opengl``, ``opengl-hq`` makes use of FBOs by default. Sometimes you
     can achieve better quality or performance by changing the fbo-format
diff --git a/video/out/gl_video.c b/video/out/gl_video.c
index 5b98e42d56..22f4100e9a 100644
--- a/video/out/gl_video.c
+++ b/video/out/gl_video.c
@@ -256,7 +256,8 @@ const struct m_sub_options gl_video_conf = {
                     {"rgba16", GL_RGBA16},
                     {"rgba16f", GL_RGBA16F},
                     {"rgba32f", GL_RGBA32F})),
-        OPT_INTRANGE("dither-depth", dither_depth, 0, -1, 16),
+        OPT_CHOICE_OR_INT("dither-depth", dither_depth, 0, -1, 16,
+                          ({"no", -1}, {"auto", 0})),
         OPT_FLAG("alpha", enable_alpha, 0),
         {0}
     },
diff --git a/video/out/vo_opengl.c b/video/out/vo_opengl.c
index ba31e0cbf5..3469cae794 100644
--- a/video/out/vo_opengl.c
+++ b/video/out/vo_opengl.c
@@ -390,7 +390,7 @@ const struct vo_driver video_out_opengl_hq = {
     .priv_size = sizeof(struct gl_priv),
     .options = options,
     .help_text = help_text,
-    .init_option_string = "lscale=lanczos2:dither-depth=0:pbo:fbo-format=rgb16",
+    .init_option_string = "lscale=lanczos2:dither-depth=auto:pbo:fbo-format=rgb16",
 };
 
 static const char help_text[] =
@@ -431,11 +431,11 @@ static const char help_text[] =
 "    sporadic and temporary image corruption.\n"
 "  dither-depth=<n>\n"
 "    Positive non-zero values select the target bit depth.\n"
-"    -1: Disable any dithering done by mpv.\n"
-"     0: Automatic selection. If output bit depth can't be detected,\n"
-"        8 bits per component are assumed.\n"
-"     8: Dither to 8 bit output.\n"
-"    Default: -1.\n"
+"     no:   Disable any dithering done by mpv.\n"
+"     auto: Automatic selection. If output bit depth can't be detected,\n"
+"           8 bits per component are assumed.\n"
+"     8:    Dither to 8 bit output.\n"
+"    Default: no.\n"
 "  debug\n"
 "    Check for OpenGL errors, i.e. call glGetError(). Also request a\n"
 "    debug OpenGL context.\n"