sub: add --ass-style-override option to disable style overrides

There are a number of options which modify ASS subtitle rendering. Most
of these do things that can interfere with the styling done by subtitle
scripts, resulting in incorrect rendering. Add the --ass-style-override
option to make it easy to disable all overrides. This helps trouble-
shooting, and makes it more practical to use the override features. (You
can simply toggle the ass-style-override property at runtime, should
one of the style override options break subtitle rendering at a certain
point.)

This mainly affects whether most --ass-* options are applied, as well
as --sub-pos. Some things, like explicit style overrides loaded with
--ass-force-style, can't be changed at runtime using the
ass-style-override property.

9 files changed, 46 insertions, 14 deletions

diff --git a/DOCS/man/en/input.rst b/DOCS/man/en/input.rst
index ab392a5696..9a4e4dcc93 100644
--- a/DOCS/man/en/input.rst
+++ b/DOCS/man/en/input.rst
@@ -296,6 +296,7 @@ sub-forced-only             x see ``--sub-forced-only``
 sub-scale                   x subtitle font size multiplicator
 ass-use-margins             x see ``--ass-use-margins``
 ass-vsfilter-aspect-compat  x see ``--ass-vsfilter-aspect-compat``
+ass-style-override          x see ``--ass-style-override``
 tv-brightness
 tv-contrast
 tv-saturation
diff --git a/DOCS/man/en/options.rst b/DOCS/man/en/options.rst
index 875b9c4b4a..6151e0d21a 100644
--- a/DOCS/man/en/options.rst
+++ b/DOCS/man/en/options.rst
@@ -176,6 +176,14 @@
     rendering text subtitles. The syntax of the file is exactly like the ``[V4
     Styles]`` / ``[V4+ Styles]`` section of SSA/ASS.
 
+--ass-style-override=<yes|no>
+    Control whether user style overrides should be applied.
+
+    :yes: Apply all the ``--ass-*`` style override options. Changing the default
+          for any of these options can lead to incorrect subtitle rendering.
+          (Default.)
+    :no:  Render subtitles as forced by subtitle scripts.
+
 --ass-top-margin=<value>
     Adds a black band at the top of the frame. The SSA/ASS renderer can place
     toptitles there (with ``--ass-use-margins``).
diff --git a/cfg-mplayer.h b/cfg-mplayer.h
index daf3c5d42e..4bd7daba1c 100644
--- a/cfg-mplayer.h
+++ b/cfg-mplayer.h
@@ -553,6 +553,8 @@ const m_option_t common_opts[] = {
     OPT_STRING("ass-border-color", ass_border_color, 0),
     OPT_STRING("ass-styles", ass_styles_file, 0),
     OPT_INTRANGE("ass-hinting", ass_hinting, 0, 0, 7),
+    OPT_CHOICE("ass-style-override", ass_style_override, 0,
+               ({"no", 0}, {"yes", 1})),
     {NULL, NULL, 0, 0, 0, 0, NULL}
 };
 
diff --git a/command.c b/command.c
index eaaa2d241b..94625352af 100644
--- a/command.c
+++ b/command.c
@@ -1477,6 +1477,7 @@ static const m_option_t mp_properties[] = {
 #ifdef CONFIG_ASS
     M_OPTION_PROPERTY_CUSTOM("ass-use-margins", property_sub_helper),
     M_OPTION_PROPERTY_CUSTOM("ass-vsfilter-aspect-compat", property_sub_helper),
+    M_OPTION_PROPERTY_CUSTOM("ass-style-override", property_sub_helper),
 #endif
 
 #ifdef CONFIG_TV
@@ -1576,6 +1577,7 @@ static struct property_osd_display {
     { "sub-forced-only", _("Forced sub only") },
     { "sub-scale", _("Sub Scale")},
     { "ass-vsfilter-aspect-compat", _("Subtitle VSFilter aspect compat")},
+    { "ass-style-override", _("ASS subtitle style override")},
 #ifdef CONFIG_TV
     { "tv-brightness", _("Brightness"), .osd_progbar = OSD_BRIGHTNESS },
     { "tv-hue", _("Hue"), .osd_progbar = OSD_HUE},
diff --git a/defaultopts.c b/defaultopts.c
index 672dbd5f5c..af470492f1 100644
--- a/defaultopts.c
+++ b/defaultopts.c
@@ -54,6 +54,7 @@ void set_default_mplayer_options(struct MPOpts *opts)
 #endif
         .ass_font_scale = 1,
         .ass_vsfilter_aspect_compat = 1,
+        .ass_style_override = 1,
         .use_embedded_fonts = 1,
 
         .lavc_param = {
diff --git a/mplayer.c b/mplayer.c
index 52316a8aa8..90e73bd7c8 100644
--- a/mplayer.c
+++ b/mplayer.c
@@ -3739,7 +3739,8 @@ static void play_current_file(struct MPContext *mpctx)
     }
 
 #ifdef CONFIG_ASS
-    ass_set_style_overrides(mpctx->ass_library, opts->ass_force_style_list);
+    if (opts->ass_style_override)
+        ass_set_style_overrides(mpctx->ass_library, opts->ass_force_style_list);
 #endif
     if (mpctx->video_out && mpctx->video_out->config_ok)
         vo_control(mpctx->video_out, VOCTRL_RESUME, NULL);
diff --git a/options.h b/options.h
index 5c8f8c0aab..61d18993fb 100644
--- a/options.h
+++ b/options.h
@@ -116,6 +116,7 @@ typedef struct MPOpts {
     char *ass_color;
     char *ass_border_color;
     char *ass_styles_file;
+    int ass_style_override;
     int ass_hinting;
     struct lavc_param {
         int workaround_bugs;
diff --git a/sub/ass_mp.c b/sub/ass_mp.c
index e2729df8ca..908a552acf 100644
--- a/sub/ass_mp.c
+++ b/sub/ass_mp.c
@@ -47,7 +47,7 @@ ASS_Track *mp_ass_default_track(ASS_Library *library, struct MPOpts *opts)
     track->PlayResY = 288;
     track->WrapStyle = 0;
 
-    if (opts->ass_styles_file)
+    if (opts->ass_styles_file && opts->ass_style_override)
         ass_read_styles(track, opts->ass_styles_file, sub_cp);
 
     if (track->n_styles == 0) {
@@ -95,7 +95,9 @@ ASS_Track *mp_ass_default_track(ASS_Library *library, struct MPOpts *opts)
         style->ScaleY = 1.;
     }
 
-    ass_process_force_style(track);
+    if (opts->ass_style_override)
+        ass_process_force_style(track);
+
     return track;
 }
 
@@ -228,20 +230,32 @@ ASS_Track *mp_ass_read_stream(ASS_Library *library, const char *fname,
 void mp_ass_configure(ASS_Renderer *priv, struct MPOpts *opts,
                       struct mp_eosd_res *dim, bool unscaled)
 {
-    int hinting;
     ass_set_frame_size(priv, dim->w, dim->h);
     ass_set_margins(priv, dim->mt, dim->mb, dim->ml, dim->mr);
-    ass_set_use_margins(priv, opts->ass_use_margins);
+
+    int set_use_margins = 0;
+    int set_sub_pos = 0;
+    float set_line_spacing = 0;
+    float set_font_scale = 1;
+    int set_hinting = 0;
+    if (opts->ass_style_override) {
+        set_use_margins = opts->ass_use_margins;
+        set_sub_pos = 100 - sub_pos;
+        set_line_spacing = opts->ass_line_spacing;
+        set_font_scale = opts->ass_font_scale;
+        if (!unscaled && (opts->ass_hinting & 4))
+            set_hinting = 0;
+        else
+            set_hinting = opts->ass_hinting & 3;
+    }
+
+    ass_set_use_margins(priv, set_use_margins);
 #if LIBASS_VERSION >= 0x01010000
-    ass_set_line_position(priv, 100 - sub_pos);
+    ass_set_line_position(priv, set_sub_pos);
 #endif
-    ass_set_font_scale(priv, opts->ass_font_scale);
-    if (!unscaled && (opts->ass_hinting & 4))
-        hinting = 0;
-    else
-        hinting = opts->ass_hinting & 3;
-    ass_set_hinting(priv, hinting);
-    ass_set_line_spacing(priv, opts->ass_line_spacing);
+    ass_set_font_scale(priv, set_font_scale);
+    ass_set_hinting(priv, set_hinting);
+    ass_set_line_spacing(priv, set_line_spacing);
 }
 
 void mp_ass_configure_fonts(ASS_Renderer *priv)
diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index 9295cab07d..fcedc9fec5 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -135,7 +135,9 @@ static void get_bitmaps(struct sh_sub *sh, struct osd_state *osd,
         return;
 
     double scale = osd->normal_scale;
-    if (ctx->vsfilter_aspect && opts->ass_vsfilter_aspect_compat)
+    bool use_vs_aspect = opts->ass_style_override
+                         ? opts->ass_vsfilter_aspect_compat : 1;
+    if (ctx->vsfilter_aspect && use_vs_aspect)
         scale = osd->vsfilter_scale;
     ASS_Renderer *renderer = osd->ass_renderer;
     mp_ass_configure(renderer, opts, &osd->dim, osd->unscaled);