vc1dec: refactor check with missing parenthesis

FATE tests updated accordingly, no visual difference.

CC: libav-stable@libav.org
Bug-Id: CID 1087087

libavcodec/vc1_mc.c

@@ -796,10 +796,9 @@ void ff_vc1_interp_mc(VC1Context *v)
     my   = s->mv[1][0][1];
     uvmx = (mx + ((mx & 3) == 3)) >> 1;
     uvmy = (my + ((my & 3) == 3)) >> 1;
-    if (v->field_mode) {
-        if (v->cur_field_type != v->ref_field_type[1])
-            my   = my   - 2 + 4 * v->cur_field_type;
-            uvmy = uvmy - 2 + 4 * v->cur_field_type;
+    if (v->field_mode && v->cur_field_type != v->ref_field_type[1]) {
+        my   = my   - 2 + 4 * v->cur_field_type;
+        uvmy = uvmy - 2 + 4 * v->cur_field_type;
     }
     if (v->fastuvmc) {
         uvmx = uvmx + ((uvmx < 0) ? -(uvmx & 1) : (uvmx & 1));

tests/ref/fate/vc1_ilaced_twomv

 #tb 0: 1/25
 0,          0,          0,        1,  3110400, 0x764f8856
-0,          2,          2,        1,  3110400, 0x1dc5592c
-0,          3,          3,        1,  3110400, 0x8ee86a47
+0,          2,          2,        1,  3110400, 0x3b615b79
+0,          3,          3,        1,  3110400, 0x4fbb6f84
 0,          4,          4,        1,  3110400, 0xc1ca8532
 0,          5,          5,        1,  3110400, 0x53efd0f9
 0,          6,          6,        1,  3110400, 0xa9605bc9
 0,          7,          7,        1,  3110400, 0xbaa9aede
-0,          8,          8,        1,  3110400, 0x7191bcf4
-0,          9,          9,        1,  3110400, 0x1d6aff98
+0,          8,          8,        1,  3110400, 0x602fbcd5
+0,          9,          9,        1,  3110400, 0x93d204b5
 0,         10,         10,        1,  3110400, 0x7b047286
 0,         11,         11,        1,  3110400, 0xa7cb2f84
 0,         12,         12,        1,  3110400, 0xfba20dd1

tests/ref/fate/vc1_sa10143

 #tb 0: 1/25
 0,          0,          0,        1,   518400, 0x89407f55
-0,          2,          2,        1,   518400, 0x8611849c
+0,          2,          2,        1,   518400, 0xaa896afd
 0,          3,          3,        1,   518400, 0x0e69ff59
-0,          4,          4,        1,   518400, 0xf31adb03
+0,          4,          4,        1,   518400, 0x0c30bfa0
 0,          5,          5,        1,   518400, 0x1a5b6a69
-0,          6,          6,        1,   518400, 0x6ae6232e
+0,          6,          6,        1,   518400, 0x23470858
 0,          7,          7,        1,   518400, 0x9a4e3c54
-0,          8,          8,        1,   518400, 0xe5852b45
+0,          8,          8,        1,   518400, 0xad63160b
 0,          9,          9,        1,   518400, 0x0fcfeebc
-0,         10,         10,        1,   518400, 0x06e22dc3
+0,         10,         10,        1,   518400, 0x20b31777
 0,         11,         11,        1,   518400, 0x9d79df09
-0,         12,         12,        1,   518400, 0xcb2c716f
+0,         12,         12,        1,   518400, 0x3e86766f
 0,         13,         13,        1,   518400, 0x638a8746
-0,         14,         14,        1,   518400, 0xf7032efd
+0,         14,         14,        1,   518400, 0x7a6c1a0e
 0,         15,         15,        1,   518400, 0x306f6cef
-0,         16,         16,        1,   518400, 0xe83d2518
+0,         16,         16,        1,   518400, 0x81f81281
 0,         17,         17,        1,   518400, 0x49ab5bf5
-0,         18,         18,        1,   518400, 0x6b336b6f
+0,         18,         18,        1,   518400, 0x8f316e44
 0,         19,         19,        1,   518400, 0x95ae00c9
-0,         20,         20,        1,   518400, 0x68ddb64f
+0,         20,         20,        1,   518400, 0xf71bb7f5
 0,         21,         21,        1,   518400, 0x5205ea68
-0,         22,         22,        1,   518400, 0xb088e617
+0,         22,         22,        1,   518400, 0x74a1d8b9
 0,         23,         23,        1,   518400, 0xa3217616
-0,         24,         24,        1,   518400, 0x1723bc53
+0,         24,         24,        1,   518400, 0x2b28bbf8
 0,         25,         25,        1,   518400, 0xf024872a
-0,         26,         26,        1,   518400, 0x2e81a8bb
+0,         26,         26,        1,   518400, 0x2fdbaaf3
 0,         27,         27,        1,   518400, 0xa3a2418e
-0,         28,         28,        1,   518400, 0xb7beffed
+0,         28,         28,        1,   518400, 0x55bfe435
 0,         29,         29,        1,   518400, 0x50fb6c94
 0,         30,         30,        1,   518400, 0x5584bb40