Increase precision of affine parameters

Improves results for videos that have a strong global motion.

lowres: -0.630%
(waterfall: -9.468%; tempete: -6.560%)

Change-Id: If9e7c7a5cdf12b607c5ef3392e10606789018f3b

av1/common/mv.h

@@ -36,8 +36,8 @@ typedef struct mv32 {
 
 #if CONFIG_GLOBAL_MOTION || CONFIG_WARPED_MOTION
 // Bits of precision used for the model
-#define WARPEDMODEL_PREC_BITS 12
-#define WARPEDMODEL_ROW3HOMO_PREC_BITS 14
+#define WARPEDMODEL_PREC_BITS 16
+#define WARPEDMODEL_ROW3HOMO_PREC_BITS 16
 
 // Bits of subpel precision for warped interpolation
 #define WARPEDPIXEL_PREC_BITS 6
@@ -105,22 +105,21 @@ typedef struct {
 // XX_MIN, XX_MAX are also computed to avoid repeated computation
 
 #define GM_TRANS_PREC_BITS 3
+#define GM_ABS_TRANS_BITS 9
 #define GM_TRANS_PREC_DIFF (WARPEDMODEL_PREC_BITS - GM_TRANS_PREC_BITS)
 #define GM_TRANS_DECODE_FACTOR (1 << GM_TRANS_PREC_DIFF)
 
-#define GM_ALPHA_PREC_BITS 12
+#define GM_ALPHA_PREC_BITS 15
+#define GM_ABS_ALPHA_BITS 12
 #define GM_ALPHA_PREC_DIFF (WARPEDMODEL_PREC_BITS - GM_ALPHA_PREC_BITS)
 #define GM_ALPHA_DECODE_FACTOR (1 << GM_ALPHA_PREC_DIFF)
 
-#define GM_ROW3HOMO_PREC_BITS 14
+#define GM_ROW3HOMO_PREC_BITS 16
+#define GM_ABS_ROW3HOMO_BITS 11
 #define GM_ROW3HOMO_PREC_DIFF \
   (WARPEDMODEL_ROW3HOMO_PREC_BITS - GM_ROW3HOMO_PREC_BITS)
 #define GM_ROW3HOMO_DECODE_FACTOR (1 << GM_ROW3HOMO_PREC_DIFF)
 
-#define GM_ABS_TRANS_BITS 9
-#define GM_ABS_ALPHA_BITS 9
-#define GM_ABS_ROW3HOMO_BITS 9
-
 #define GM_TRANS_MAX (1 << GM_ABS_TRANS_BITS)
 #define GM_ALPHA_MAX (1 << GM_ABS_ALPHA_BITS)
 #define GM_ROW3HOMO_MAX (1 << GM_ABS_ROW3HOMO_BITS)