cocoa: improve refresh rate fallback code

Apparently CoreGraphics reports the actual refresh rate. DisplayLink can also
query the nominal refresh rate of the display so we use that as fallback
instead of the fugly 60fps hardcode added in aeb1fca0d.

Props to people on https://github.com/glfw/glfw/issues/137

1 files changed, 14 insertions, 9 deletions

diff --git a/video/out/cocoa_common.m b/video/out/cocoa_common.m
index 306b5aedd2..8d1e0ef653 100644
--- a/video/out/cocoa_common.m
+++ b/video/out/cocoa_common.m
@@ -267,14 +267,17 @@ static void vo_cocoa_update_screen_fps(struct vo *vo)
     CGDisplayModeRef mode = CGDisplayCopyDisplayMode(did);
     s->screen_fps = CGDisplayModeGetRefreshRate(mode);
     CGDisplayModeRelease(mode);
+
     if (s->screen_fps == 0.0) {
-        // Most internal Apple monitors and laptop monitors report 0 instead
-        // of 60fps. Assume them to be 60hz. This is technically incorrect but
-        // works most of the time, and seems to be used in most open source
-        // software for lack of a better Apple API.
-        MP_VERBOSE(vo, "CoreGraphics reports a 0fps display. Assuming internal "
-                       "Apple monitor @ 60fps instead.\n");
-        s->screen_fps = 60.0;
+        // Fallback to using Nominal refresh rate from DisplayLink,
+        // CVDisplayLinkGet *Actual* OutputVideoRefreshPeriod seems to
+        // return 0 as well if CG returns 0
+        CVDisplayLinkRef link;
+        CVDisplayLinkCreateWithCGDisplay(did, &link);
+        const CVTime t = CVDisplayLinkGetNominalOutputVideoRefreshPeriod(link);
+        if (!(t.flags & kCVTimeIsIndefinite))
+            s->screen_fps = (t.timeScale / (double) t.timeValue);
+        CVDisplayLinkRelease(link);
     }
 }
 
@@ -673,8 +676,10 @@ int vo_cocoa_control(struct vo *vo, int *events, int request, void *arg)
         vo_cocoa_control_get_icc_profile(vo, arg);
         return VO_TRUE;
     case VOCTRL_GET_DISPLAY_FPS:
-        *(double *)arg = vo->cocoa->screen_fps;
-        return VO_TRUE;
+        if (vo->cocoa->screen_fps > 0.0) {
+            *(double *)arg = vo->cocoa->screen_fps;
+            return VO_TRUE;
+        }
     }
     return VO_NOTIMPL;
 }