vo_gpu: fix 3DLUT precision

Using cmsFLAGS_HIGHRESPRECALC results in Little-CMS generating an
internal 49x49x49 3DLUT, from which it then samples our own 3DLUT. This
is completely pointless and not only destroys the accuracy of the 3DLUT,
but also results in no additional gain from increasing the 3DLUT
precision further.

The correct flag for us to be using is cmsFLAGS_NOOPTIMIZE, which
suppresses this internal 3DLUT generation and gives us the full
precision. We can also specify cmsFLAGS_NOCACHE, which is negligible but
in theory prevents Little-CMS from unnecessary pixel equality tests.

1 files changed, 3 insertions, 2 deletions

diff --git a/video/out/gpu/lcms.c b/video/out/gpu/lcms.c
index 17edf96f3b..09c4a696b1 100644
--- a/video/out/gpu/lcms.c
+++ b/video/out/gpu/lcms.c
@@ -289,7 +289,7 @@ static cmsHPROFILE get_vid_profile(struct gl_lcms *p, cmsContext cms,
             cmsHPROFILE xyz_profile = cmsCreateXYZProfile();
             cmsHTRANSFORM xyz2src = cmsCreateTransformTHR(cms,
                     xyz_profile, TYPE_XYZ_DBL, rev_profile, TYPE_RGB_DBL,
-                    intent, 0);
+                    intent, cmsFLAGS_NOCACHE | cmsFLAGS_NOOPTIMIZE);
             cmsFreeToneCurve(linear);
             cmsCloseProfile(rev_profile);
             cmsCloseProfile(xyz_profile);
@@ -429,7 +429,8 @@ bool gl_lcms_get_lut3d(struct gl_lcms *p, struct lut3d **result_lut3d,
     cmsHTRANSFORM trafo = cmsCreateTransformTHR(cms, vid_hprofile, TYPE_RGB_16,
                                                 profile, TYPE_RGBA_16,
                                                 p->opts->intent,
-                                                cmsFLAGS_HIGHRESPRECALC |
+                                                cmsFLAGS_NOCACHE |
+                                                cmsFLAGS_NOOPTIMIZE |
                                                 cmsFLAGS_BLACKPOINTCOMPENSATION);
     cmsCloseProfile(profile);
     cmsCloseProfile(vid_hprofile);