ply/m46471: clip RGB to YCbCr conversion for full range RGB input

Using the Rec.709 colour matrix with full range RGB signals, it is
necessary to clip the output to avoid exceeding the attribute bitdepth.

tmc3/PCCPointSet.h

@@ -756,14 +756,12 @@ public:
       const uint8_t r = color[0];
       const uint8_t g = color[1];
       const uint8_t b = color[2];
-      const double y = std::round(0.212600 * r + 0.715200 * g + 0.072200 * b);
-      const double u =
-        std::round(-0.114572 * r - 0.385428 * g + 0.500000 * b + 128.0);
-      const double v =
-        std::round(0.500000 * r - 0.454153 * g - 0.045847 * b + 128.0);
-      assert(
-        y >= 0.0 && y <= 255.0 && u >= 0.0 && u <= 255.0 && v >= 0.0
-        && v <= 255.0);
+      const double y = PCCClip(
+        std::round(0.212600 * r + 0.715200 * g + 0.072200 * b), 0., 255.);
+      const double u = PCCClip(
+        std::round(-0.114572 * r - 0.385428 * g + 0.5 * b + 128.0), 0., 255.);
+      const double v = PCCClip(
+        std::round(0.5 * r - 0.454153 * g - 0.045847 * b + 128.0), 0., 255.);
       color[0] = static_cast<uint8_t>(y);
       color[1] = static_cast<uint8_t>(u);
       color[2] = static_cast<uint8_t>(v);