sws/yuv2rgb: avoid a few ub on signed left shifts

libswscale/yuv2rgb.c

@@ -824,18 +824,18 @@ av_cold int ff_yuv2rgb_c_init_tables(SwsContext *c, const int inv_table[4],
     c->ugCoeff = roundToInt16(cgu * 8192) * 0x0001000100010001ULL;
     c->yOffset = roundToInt16(oy  *    8) * 0x0001000100010001ULL;
 
-    c->yuv2rgb_y_coeff   = (int16_t)roundToInt16(cy  << 13);
-    c->yuv2rgb_y_offset  = (int16_t)roundToInt16(oy  <<  9);
-    c->yuv2rgb_v2r_coeff = (int16_t)roundToInt16(crv << 13);
-    c->yuv2rgb_v2g_coeff = (int16_t)roundToInt16(cgv << 13);
-    c->yuv2rgb_u2g_coeff = (int16_t)roundToInt16(cgu << 13);
-    c->yuv2rgb_u2b_coeff = (int16_t)roundToInt16(cbu << 13);
+    c->yuv2rgb_y_coeff   = (int16_t)roundToInt16(cy  * (1 << 13));
+    c->yuv2rgb_y_offset  = (int16_t)roundToInt16(oy  * (1 <<  9));
+    c->yuv2rgb_v2r_coeff = (int16_t)roundToInt16(crv * (1 << 13));
+    c->yuv2rgb_v2g_coeff = (int16_t)roundToInt16(cgv * (1 << 13));
+    c->yuv2rgb_u2g_coeff = (int16_t)roundToInt16(cgu * (1 << 13));
+    c->yuv2rgb_u2b_coeff = (int16_t)roundToInt16(cbu * (1 << 13));
 
     //scale coefficients by cy
-    crv = ((crv << 16) + 0x8000) / FFMAX(cy, 1);
-    cbu = ((cbu << 16) + 0x8000) / FFMAX(cy, 1);
-    cgu = ((cgu << 16) + 0x8000) / FFMAX(cy, 1);
-    cgv = ((cgv << 16) + 0x8000) / FFMAX(cy, 1);
+    crv = ((crv * (1 << 16)) + 0x8000) / FFMAX(cy, 1);
+    cbu = ((cbu * (1 << 16)) + 0x8000) / FFMAX(cy, 1);
+    cgu = ((cgu * (1 << 16)) + 0x8000) / FFMAX(cy, 1);
+    cgv = ((cgv * (1 << 16)) + 0x8000) / FFMAX(cy, 1);
 
     av_freep(&c->yuvTable);