shithub: dav1d

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Add clamping back to mv projection

Clamping in the motion vector projection calculation is required by spec.
In commit aca57bf3db00c29e90605656f1015561d1d67c2d
a rewrite of the function omitted the clamping. This commit readds the
clamping.

--- a/src/refmvs.c

+++ b/src/refmvs.c

@@ -184,8 +184,11 @@

     assert(num > -32 && num < 32);

     const int dm = div_mult[den];

     const int y = mv.y * num * dm, x = mv.x * num * dm;

-    return (union mv) { .y = (y + 8192 + (y >> 31)) >> 14,

-                        .x = (x + 8192 + (x >> 31)) >> 14 };

+    // Round and clip according to AV1 spec section 7.9.3

+    return (union mv) { // 0x3fff == (1 << 14) - 1

+        .y = iclip((y + 8192 + (y >> 31)) >> 14, -0x3fff, 0x3fff),

+        .x = iclip((x + 8192 + (x >> 31)) >> 14, -0x3fff, 0x3fff)

+    };

 }

 static void add_temporal_candidate(const refmvs_frame *const rf,