avfilter/vf_v360: fix small artifacts with tetrahedron inputs

libavfilter/vf_v360.c

@@ -2656,8 +2656,8 @@ static void xyz_to_tetrahedron(const V360Context *s,
         uf = 0.75f - 0.25f * x;
     }
 
-    uf *= width  - 1;
-    vf *= height - 1;
+    uf *= width;
+    vf *= height;
 
     ui = floorf(uf);
     vi = floorf(vf);
@@ -2667,7 +2667,7 @@ static void xyz_to_tetrahedron(const V360Context *s,
 
     for (int i = -1; i < 3; i++) {
         for (int j = -1; j < 3; j++) {
-            us[i + 1][j + 1] = av_clip(ui + j, 0, width  - 1);
+            us[i + 1][j + 1] = mod(ui + j, width);
             vs[i + 1][j + 1] = av_clip(vi + i, 0, height - 1);
         }
     }