Enable CDEF filter for 4:2:2

Add missing logic to map CDEF direction for chroma planes.

AWCY results on derf-720p-422 at the default speed show a 9.9% decrease
in encoding speed:

   PSNR | PSNR Cb | PSNR Cr | PSNR HVS |    SSIM | MS SSIM | CIEDE 2000
-2.5572 |  0.4582 | -1.0744 |  -2.0057 | -0.1799 | -1.0506 |    -2.9736

Author: barrbrain

src/cdef.rs

@@ -522,6 +522,8 @@ pub fn cdef_filter_superblock<T: Pixel, U: Pixel>(
             let local_pri_strength;
             let local_sec_strength;
             let mut local_damping: i32 = cdef_damping + coeff_shift;
+            // See `Cdef_Uv_Dir` constant lookup table in Section 7.15.1
+            // <https://aomediacodec.github.io/av1-spec/#cdef-block-process>
             let local_dir = if p == 0 {
               local_pri_strength =
                 adjust_strength(cdef_pri_y_strength << coeff_shift, var);
@@ -536,7 +538,11 @@ pub fn cdef_filter_superblock<T: Pixel, U: Pixel>(
               local_sec_strength = cdef_sec_uv_strength << coeff_shift;
               local_damping -= 1;
               if cdef_pri_uv_strength != 0 {
-                dir as usize
+                if xdec != ydec {
+                  [7, 0, 2, 4, 5, 6, 6, 6][dir as usize]
+                } else {
+                  dir as usize
+                }
               } else {
                 0
               }

src/encoder.rs

@@ -246,9 +246,7 @@ impl Sequence {
       enable_ref_frame_mvs: false,
       enable_warped_motion: false,
       enable_superres: false,
-      enable_cdef: config.speed_settings.cdef
-        && config.chroma_sampling != ChromaSampling::Cs422
-        && enable_restoration_filters,
+      enable_cdef: config.speed_settings.cdef && enable_restoration_filters,
       enable_restoration: config.speed_settings.lrf
         && config.chroma_sampling != ChromaSampling::Cs422
         && enable_restoration_filters,