diff --git a/tests/h264_intra_pred_8x8_luma_ref.c b/tests/h264_intra_pred_8x8_luma_ref.c
index 3bf0524..14d7b06 100644
--- a/tests/h264_intra_pred_8x8_luma_ref.c
+++ b/tests/h264_intra_pred_8x8_luma_ref.c
@@ -121,3 +121,185 @@ void daedalus_h264_pred_8x8l_dc_ref(uint8_t *dst, ptrdiff_t stride)
     for (int r = 0; r < 8; r++)
         for (int c = 0; c < 8; c++) dst[r * stride + c] = v;
 }
+
+/* --- 6 directional modes for Intra_8x8 (H.264 §8.3.2.1.5..§8.3.2.1.10).
+ * Transcribed from FFmpeg libavcodec/h264pred_template.c
+ * pred8x8l_{down_left, down_right, vertical_right, horizontal_down,
+ * vertical_left, horizontal_up} (LGPL-2.1+ in the original; algorithm
+ * reproduced here for test purposes).
+ *
+ * All 6 use the same FILTERED reference samples produced by
+ * filter_refs() above.  Mapping from FFmpeg's t0..t15 / l0..l7 / lt
+ * notation:
+ *     tN = FT(N)   for N in 0..15
+ *     lN = FL(N)   for N in 0..7
+ *     lt = FTL
+ *
+ * SRC(x,y) maps to dst[y*stride + x] (col x, row y).
+ */
+#define SRC(x, y) dst[(y) * stride + (x)]
+#define T(i)  FT(i)
+#define L(j)  FL(j)
+#define LT    FTL
+
+/* Mode 3 DDL (Diagonal_Down_Left) — uses TOP + TOP_RIGHT, no LEFT. */
+void daedalus_h264_pred_8x8l_ddl_ref(uint8_t *dst, ptrdiff_t stride)
+{
+    uint8_t filt[25];
+    filter_refs(dst, stride, filt);
+    SRC(0,0)= (T(0) + 2*T(1) + T(2) + 2) >> 2;
+    SRC(0,1)=SRC(1,0)= (T(1) + 2*T(2) + T(3) + 2) >> 2;
+    SRC(0,2)=SRC(1,1)=SRC(2,0)= (T(2) + 2*T(3) + T(4) + 2) >> 2;
+    SRC(0,3)=SRC(1,2)=SRC(2,1)=SRC(3,0)= (T(3) + 2*T(4) + T(5) + 2) >> 2;
+    SRC(0,4)=SRC(1,3)=SRC(2,2)=SRC(3,1)=SRC(4,0)= (T(4) + 2*T(5) + T(6) + 2) >> 2;
+    SRC(0,5)=SRC(1,4)=SRC(2,3)=SRC(3,2)=SRC(4,1)=SRC(5,0)= (T(5) + 2*T(6) + T(7) + 2) >> 2;
+    SRC(0,6)=SRC(1,5)=SRC(2,4)=SRC(3,3)=SRC(4,2)=SRC(5,1)=SRC(6,0)= (T(6) + 2*T(7) + T(8) + 2) >> 2;
+    SRC(0,7)=SRC(1,6)=SRC(2,5)=SRC(3,4)=SRC(4,3)=SRC(5,2)=SRC(6,1)=SRC(7,0)= (T(7) + 2*T(8) + T(9) + 2) >> 2;
+    SRC(1,7)=SRC(2,6)=SRC(3,5)=SRC(4,4)=SRC(5,3)=SRC(6,2)=SRC(7,1)= (T(8) + 2*T(9) + T(10) + 2) >> 2;
+    SRC(2,7)=SRC(3,6)=SRC(4,5)=SRC(5,4)=SRC(6,3)=SRC(7,2)= (T(9) + 2*T(10) + T(11) + 2) >> 2;
+    SRC(3,7)=SRC(4,6)=SRC(5,5)=SRC(6,4)=SRC(7,3)= (T(10) + 2*T(11) + T(12) + 2) >> 2;
+    SRC(4,7)=SRC(5,6)=SRC(6,5)=SRC(7,4)= (T(11) + 2*T(12) + T(13) + 2) >> 2;
+    SRC(5,7)=SRC(6,6)=SRC(7,5)= (T(12) + 2*T(13) + T(14) + 2) >> 2;
+    SRC(6,7)=SRC(7,6)= (T(13) + 2*T(14) + T(15) + 2) >> 2;
+    SRC(7,7)= (T(14) + 3*T(15) + 2) >> 2;
+}
+
+/* Mode 4 DDR (Diagonal_Down_Right). */
+void daedalus_h264_pred_8x8l_ddr_ref(uint8_t *dst, ptrdiff_t stride)
+{
+    uint8_t filt[25];
+    filter_refs(dst, stride, filt);
+    SRC(0,7)= (L(7) + 2*L(6) + L(5) + 2) >> 2;
+    SRC(0,6)=SRC(1,7)= (L(6) + 2*L(5) + L(4) + 2) >> 2;
+    SRC(0,5)=SRC(1,6)=SRC(2,7)= (L(5) + 2*L(4) + L(3) + 2) >> 2;
+    SRC(0,4)=SRC(1,5)=SRC(2,6)=SRC(3,7)= (L(4) + 2*L(3) + L(2) + 2) >> 2;
+    SRC(0,3)=SRC(1,4)=SRC(2,5)=SRC(3,6)=SRC(4,7)= (L(3) + 2*L(2) + L(1) + 2) >> 2;
+    SRC(0,2)=SRC(1,3)=SRC(2,4)=SRC(3,5)=SRC(4,6)=SRC(5,7)= (L(2) + 2*L(1) + L(0) + 2) >> 2;
+    SRC(0,1)=SRC(1,2)=SRC(2,3)=SRC(3,4)=SRC(4,5)=SRC(5,6)=SRC(6,7)= (L(1) + 2*L(0) + LT + 2) >> 2;
+    SRC(0,0)=SRC(1,1)=SRC(2,2)=SRC(3,3)=SRC(4,4)=SRC(5,5)=SRC(6,6)=SRC(7,7)= (L(0) + 2*LT + T(0) + 2) >> 2;
+    SRC(1,0)=SRC(2,1)=SRC(3,2)=SRC(4,3)=SRC(5,4)=SRC(6,5)=SRC(7,6)= (LT + 2*T(0) + T(1) + 2) >> 2;
+    SRC(2,0)=SRC(3,1)=SRC(4,2)=SRC(5,3)=SRC(6,4)=SRC(7,5)= (T(0) + 2*T(1) + T(2) + 2) >> 2;
+    SRC(3,0)=SRC(4,1)=SRC(5,2)=SRC(6,3)=SRC(7,4)= (T(1) + 2*T(2) + T(3) + 2) >> 2;
+    SRC(4,0)=SRC(5,1)=SRC(6,2)=SRC(7,3)= (T(2) + 2*T(3) + T(4) + 2) >> 2;
+    SRC(5,0)=SRC(6,1)=SRC(7,2)= (T(3) + 2*T(4) + T(5) + 2) >> 2;
+    SRC(6,0)=SRC(7,1)= (T(4) + 2*T(5) + T(6) + 2) >> 2;
+    SRC(7,0)= (T(5) + 2*T(6) + T(7) + 2) >> 2;
+}
+
+/* Mode 5 VR (Vertical_Right). */
+void daedalus_h264_pred_8x8l_vr_ref(uint8_t *dst, ptrdiff_t stride)
+{
+    uint8_t filt[25];
+    filter_refs(dst, stride, filt);
+    SRC(0,6)= (L(5) + 2*L(4) + L(3) + 2) >> 2;
+    SRC(0,7)= (L(6) + 2*L(5) + L(4) + 2) >> 2;
+    SRC(0,4)=SRC(1,6)= (L(3) + 2*L(2) + L(1) + 2) >> 2;
+    SRC(0,5)=SRC(1,7)= (L(4) + 2*L(3) + L(2) + 2) >> 2;
+    SRC(0,2)=SRC(1,4)=SRC(2,6)= (L(1) + 2*L(0) + LT + 2) >> 2;
+    SRC(0,3)=SRC(1,5)=SRC(2,7)= (L(2) + 2*L(1) + L(0) + 2) >> 2;
+    SRC(0,1)=SRC(1,3)=SRC(2,5)=SRC(3,7)= (L(0) + 2*LT + T(0) + 2) >> 2;
+    SRC(0,0)=SRC(1,2)=SRC(2,4)=SRC(3,6)= (LT + T(0) + 1) >> 1;
+    SRC(1,1)=SRC(2,3)=SRC(3,5)=SRC(4,7)= (LT + 2*T(0) + T(1) + 2) >> 2;
+    SRC(1,0)=SRC(2,2)=SRC(3,4)=SRC(4,6)= (T(0) + T(1) + 1) >> 1;
+    SRC(2,1)=SRC(3,3)=SRC(4,5)=SRC(5,7)= (T(0) + 2*T(1) + T(2) + 2) >> 2;
+    SRC(2,0)=SRC(3,2)=SRC(4,4)=SRC(5,6)= (T(1) + T(2) + 1) >> 1;
+    SRC(3,1)=SRC(4,3)=SRC(5,5)=SRC(6,7)= (T(1) + 2*T(2) + T(3) + 2) >> 2;
+    SRC(3,0)=SRC(4,2)=SRC(5,4)=SRC(6,6)= (T(2) + T(3) + 1) >> 1;
+    SRC(4,1)=SRC(5,3)=SRC(6,5)=SRC(7,7)= (T(2) + 2*T(3) + T(4) + 2) >> 2;
+    SRC(4,0)=SRC(5,2)=SRC(6,4)=SRC(7,6)= (T(3) + T(4) + 1) >> 1;
+    SRC(5,1)=SRC(6,3)=SRC(7,5)= (T(3) + 2*T(4) + T(5) + 2) >> 2;
+    SRC(5,0)=SRC(6,2)=SRC(7,4)= (T(4) + T(5) + 1) >> 1;
+    SRC(6,1)=SRC(7,3)= (T(4) + 2*T(5) + T(6) + 2) >> 2;
+    SRC(6,0)=SRC(7,2)= (T(5) + T(6) + 1) >> 1;
+    SRC(7,1)= (T(5) + 2*T(6) + T(7) + 2) >> 2;
+    SRC(7,0)= (T(6) + T(7) + 1) >> 1;
+}
+
+/* Mode 6 HD (Horizontal_Down). */
+void daedalus_h264_pred_8x8l_hd_ref(uint8_t *dst, ptrdiff_t stride)
+{
+    uint8_t filt[25];
+    filter_refs(dst, stride, filt);
+    SRC(0,7)= (L(6) + L(7) + 1) >> 1;
+    SRC(1,7)= (L(5) + 2*L(6) + L(7) + 2) >> 2;
+    SRC(0,6)=SRC(2,7)= (L(5) + L(6) + 1) >> 1;
+    SRC(1,6)=SRC(3,7)= (L(4) + 2*L(5) + L(6) + 2) >> 2;
+    SRC(0,5)=SRC(2,6)=SRC(4,7)= (L(4) + L(5) + 1) >> 1;
+    SRC(1,5)=SRC(3,6)=SRC(5,7)= (L(3) + 2*L(4) + L(5) + 2) >> 2;
+    SRC(0,4)=SRC(2,5)=SRC(4,6)=SRC(6,7)= (L(3) + L(4) + 1) >> 1;
+    SRC(1,4)=SRC(3,5)=SRC(5,6)=SRC(7,7)= (L(2) + 2*L(3) + L(4) + 2) >> 2;
+    SRC(0,3)=SRC(2,4)=SRC(4,5)=SRC(6,6)= (L(2) + L(3) + 1) >> 1;
+    SRC(1,3)=SRC(3,4)=SRC(5,5)=SRC(7,6)= (L(1) + 2*L(2) + L(3) + 2) >> 2;
+    SRC(0,2)=SRC(2,3)=SRC(4,4)=SRC(6,5)= (L(1) + L(2) + 1) >> 1;
+    SRC(1,2)=SRC(3,3)=SRC(5,4)=SRC(7,5)= (L(0) + 2*L(1) + L(2) + 2) >> 2;
+    SRC(0,1)=SRC(2,2)=SRC(4,3)=SRC(6,4)= (L(0) + L(1) + 1) >> 1;
+    SRC(1,1)=SRC(3,2)=SRC(5,3)=SRC(7,4)= (LT + 2*L(0) + L(1) + 2) >> 2;
+    SRC(0,0)=SRC(2,1)=SRC(4,2)=SRC(6,3)= (LT + L(0) + 1) >> 1;
+    SRC(1,0)=SRC(3,1)=SRC(5,2)=SRC(7,3)= (L(0) + 2*LT + T(0) + 2) >> 2;
+    SRC(2,0)=SRC(4,1)=SRC(6,2)= (T(1) + 2*T(0) + LT + 2) >> 2;
+    SRC(3,0)=SRC(5,1)=SRC(7,2)= (T(2) + 2*T(1) + T(0) + 2) >> 2;
+    SRC(4,0)=SRC(6,1)= (T(3) + 2*T(2) + T(1) + 2) >> 2;
+    SRC(5,0)=SRC(7,1)= (T(4) + 2*T(3) + T(2) + 2) >> 2;
+    SRC(6,0)= (T(5) + 2*T(4) + T(3) + 2) >> 2;
+    SRC(7,0)= (T(6) + 2*T(5) + T(4) + 2) >> 2;
+}
+
+/* Mode 7 VL (Vertical_Left) — uses TOP + TOP_RIGHT only. */
+void daedalus_h264_pred_8x8l_vl_ref(uint8_t *dst, ptrdiff_t stride)
+{
+    uint8_t filt[25];
+    filter_refs(dst, stride, filt);
+    SRC(0,0)= (T(0) + T(1) + 1) >> 1;
+    SRC(0,1)= (T(0) + 2*T(1) + T(2) + 2) >> 2;
+    SRC(0,2)=SRC(1,0)= (T(1) + T(2) + 1) >> 1;
+    SRC(0,3)=SRC(1,1)= (T(1) + 2*T(2) + T(3) + 2) >> 2;
+    SRC(0,4)=SRC(1,2)=SRC(2,0)= (T(2) + T(3) + 1) >> 1;
+    SRC(0,5)=SRC(1,3)=SRC(2,1)= (T(2) + 2*T(3) + T(4) + 2) >> 2;
+    SRC(0,6)=SRC(1,4)=SRC(2,2)=SRC(3,0)= (T(3) + T(4) + 1) >> 1;
+    SRC(0,7)=SRC(1,5)=SRC(2,3)=SRC(3,1)= (T(3) + 2*T(4) + T(5) + 2) >> 2;
+    SRC(1,6)=SRC(2,4)=SRC(3,2)=SRC(4,0)= (T(4) + T(5) + 1) >> 1;
+    SRC(1,7)=SRC(2,5)=SRC(3,3)=SRC(4,1)= (T(4) + 2*T(5) + T(6) + 2) >> 2;
+    SRC(2,6)=SRC(3,4)=SRC(4,2)=SRC(5,0)= (T(5) + T(6) + 1) >> 1;
+    SRC(2,7)=SRC(3,5)=SRC(4,3)=SRC(5,1)= (T(5) + 2*T(6) + T(7) + 2) >> 2;
+    SRC(3,6)=SRC(4,4)=SRC(5,2)=SRC(6,0)= (T(6) + T(7) + 1) >> 1;
+    SRC(3,7)=SRC(4,5)=SRC(5,3)=SRC(6,1)= (T(6) + 2*T(7) + T(8) + 2) >> 2;
+    SRC(4,6)=SRC(5,4)=SRC(6,2)=SRC(7,0)= (T(7) + T(8) + 1) >> 1;
+    SRC(4,7)=SRC(5,5)=SRC(6,3)=SRC(7,1)= (T(7) + 2*T(8) + T(9) + 2) >> 2;
+    SRC(5,6)=SRC(6,4)=SRC(7,2)= (T(8) + T(9) + 1) >> 1;
+    SRC(5,7)=SRC(6,5)=SRC(7,3)= (T(8) + 2*T(9) + T(10) + 2) >> 2;
+    SRC(6,6)=SRC(7,4)= (T(9) + T(10) + 1) >> 1;
+    SRC(6,7)=SRC(7,5)= (T(9) + 2*T(10) + T(11) + 2) >> 2;
+    SRC(7,6)= (T(10) + T(11) + 1) >> 1;
+    SRC(7,7)= (T(10) + 2*T(11) + T(12) + 2) >> 2;
+}
+
+/* Mode 8 HU (Horizontal_Up) — uses LEFT only. */
+void daedalus_h264_pred_8x8l_hu_ref(uint8_t *dst, ptrdiff_t stride)
+{
+    uint8_t filt[25];
+    filter_refs(dst, stride, filt);
+    SRC(0,0)= (L(0) + L(1) + 1) >> 1;
+    SRC(1,0)= (L(0) + 2*L(1) + L(2) + 2) >> 2;
+    SRC(0,1)=SRC(2,0)= (L(1) + L(2) + 1) >> 1;
+    SRC(1,1)=SRC(3,0)= (L(1) + 2*L(2) + L(3) + 2) >> 2;
+    SRC(0,2)=SRC(2,1)=SRC(4,0)= (L(2) + L(3) + 1) >> 1;
+    SRC(1,2)=SRC(3,1)=SRC(5,0)= (L(2) + 2*L(3) + L(4) + 2) >> 2;
+    SRC(0,3)=SRC(2,2)=SRC(4,1)=SRC(6,0)= (L(3) + L(4) + 1) >> 1;
+    SRC(1,3)=SRC(3,2)=SRC(5,1)=SRC(7,0)= (L(3) + 2*L(4) + L(5) + 2) >> 2;
+    SRC(0,4)=SRC(2,3)=SRC(4,2)=SRC(6,1)= (L(4) + L(5) + 1) >> 1;
+    SRC(1,4)=SRC(3,3)=SRC(5,2)=SRC(7,1)= (L(4) + 2*L(5) + L(6) + 2) >> 2;
+    SRC(0,5)=SRC(2,4)=SRC(4,3)=SRC(6,2)= (L(5) + L(6) + 1) >> 1;
+    SRC(1,5)=SRC(3,4)=SRC(5,3)=SRC(7,2)= (L(5) + 2*L(6) + L(7) + 2) >> 2;
+    SRC(0,6)=SRC(2,5)=SRC(4,4)=SRC(6,3)= (L(6) + L(7) + 1) >> 1;
+    SRC(1,6)=SRC(3,5)=SRC(5,4)=SRC(7,3)= (L(6) + 3*L(7) + 2) >> 2;
+    /* 20 positions all = L(7) per FFmpeg lines 1097-1100. */
+    SRC(0,7)=SRC(1,7)=SRC(2,6)=SRC(2,7)=SRC(3,6)=
+    SRC(3,7)=SRC(4,5)=SRC(4,6)=SRC(4,7)=SRC(5,5)=
+    SRC(5,6)=SRC(5,7)=SRC(6,4)=SRC(6,5)=SRC(6,6)=
+    SRC(6,7)=SRC(7,4)=SRC(7,5)=SRC(7,6)=SRC(7,7)= L(7);
+}
+
+#undef SRC
+#undef T
+#undef L
+#undef LT
diff --git a/tests/test_intra_pred_8x8_luma.c b/tests/test_intra_pred_8x8_luma.c
index ac8b03c..5beffda 100644
--- a/tests/test_intra_pred_8x8_luma.c
+++ b/tests/test_intra_pred_8x8_luma.c
@@ -17,6 +17,12 @@
 extern void daedalus_h264_pred_8x8l_vertical_ref(uint8_t *dst, ptrdiff_t stride);
 extern void daedalus_h264_pred_8x8l_horizontal_ref(uint8_t *dst, ptrdiff_t stride);
 extern void daedalus_h264_pred_8x8l_dc_ref(uint8_t *dst, ptrdiff_t stride);
+extern void daedalus_h264_pred_8x8l_ddl_ref(uint8_t *dst, ptrdiff_t stride);
+extern void daedalus_h264_pred_8x8l_ddr_ref(uint8_t *dst, ptrdiff_t stride);
+extern void daedalus_h264_pred_8x8l_vr_ref(uint8_t *dst, ptrdiff_t stride);
+extern void daedalus_h264_pred_8x8l_hd_ref(uint8_t *dst, ptrdiff_t stride);
+extern void daedalus_h264_pred_8x8l_vl_ref(uint8_t *dst, ptrdiff_t stride);
+extern void daedalus_h264_pred_8x8l_hu_ref(uint8_t *dst, ptrdiff_t stride);
 
 #define STRIDE 17
 #define ROWS   9
@@ -133,7 +139,32 @@ int main(void)
         fail |= (diff == 0) ? 0 : 1;
     }
 
-    if (fail == 0) printf("\nALL Intra_8x8 luma PASS (3 modes — V, H, DC)\n");
+    /* Directional modes — uniform-context sanity tests.  With all
+     * neighbours = N, the 1-2-1 filter produces uniform N, and any
+     * 3-tap / 2-tap on uniform N produces N.  So every directional
+     * mode should output uniform N on uniform input. */
+    {
+        typedef void (*pred_fn_t)(uint8_t *dst, ptrdiff_t stride);
+        struct { const char *name; pred_fn_t fn; } modes[] = {
+            { "DDL (mode 3, uniform)",        daedalus_h264_pred_8x8l_ddl_ref },
+            { "DDR (mode 4, uniform)",        daedalus_h264_pred_8x8l_ddr_ref },
+            { "VR (mode 5, uniform)",         daedalus_h264_pred_8x8l_vr_ref  },
+            { "HD (mode 6, uniform)",         daedalus_h264_pred_8x8l_hd_ref  },
+            { "VL (mode 7, uniform)",         daedalus_h264_pred_8x8l_vl_ref  },
+            { "HU (mode 8, uniform)",         daedalus_h264_pred_8x8l_hu_ref  },
+        };
+        for (size_t i = 0; i < sizeof(modes)/sizeof(modes[0]); i++) {
+            uint8_t buf[ROWS][STRIDE];
+            int t[16], l[8];
+            for (int k = 0; k < 16; k++) t[k] = 120;
+            for (int k = 0; k < 8;  k++) l[k] = 120;
+            set_ctx(buf, 120, t, l);
+            modes[i].fn(&buf[1][1], STRIDE);
+            fail |= check_uniform(buf, modes[i].name, 120);
+        }
+    }
+
+    if (fail == 0) printf("\nALL Intra_8x8 luma PASS (9 modes — V, H, DC, DDL, DDR, VR, HD, VL, HU)\n");
     else           fprintf(stderr, "\n%d test(s) FAILED\n", fail);
     return fail ? 1 : 0;
 }