command: use property_time() for sub-start and sub-end

This gives these properties the "time" type, which allows them to be pretty-printed as HH:MM:SS easily (but also still allows raw formatting using e.g. ${=sub-start}).

DOCS/interface-changes/sub-times.txt

@@ -0,0 +1 @@
+change type of `sub-start` and `sub-end` properties to time

DOCS/man/input.rst

@@ -2867,6 +2867,11 @@ Property list
     subtitles, returns the first start time. If no current subtitle is present
     null is returned instead.
 
+    This has a sub-property:
+
+    ``sub-start/full``
+        ``sub-start`` with milliseconds.
+
 ``secondary-sub-start``
     Same as ``sub-start``, but for the secondary subtitles.
 
@@ -2876,6 +2881,11 @@ Property list
     if it's present but has unknown or incorrect duration, null is returned
     instead.
 
+    This has a sub-property:
+
+    ``sub-end/full``
+        ``sub-end`` with milliseconds.
+
 ``secondary-sub-end``
     Same as ``sub-end``, but for the secondary subtitles.
 

player/command.c

@@ -3062,7 +3062,7 @@ static int mp_property_sub_start(void *ctx, struct m_property *prop,
     double start = get_times(ctx, prop, action, arg).start;
     if (start == MP_NOPTS_VALUE)
         return M_PROPERTY_UNAVAILABLE;
-    return m_property_double_ro(action, arg, start);
+    return property_time(action, arg, start);
 }
 
 
@@ -3072,7 +3072,7 @@ static int mp_property_sub_end(void *ctx, struct m_property *prop,
     double end = get_times(ctx, prop, action, arg).end;
     if (end == MP_NOPTS_VALUE)
         return M_PROPERTY_UNAVAILABLE;
-    return m_property_double_ro(action, arg, end);
+    return property_time(action, arg, end);
 }
 
 static int mp_property_playlist_current_pos(void *ctx, struct m_property *prop,