commit 09756715f1b34b87272f92430e6ee548644fe24b
author Angie Chiang <angiebird@google.com> Wed Feb 21 12:18:11 2018 -0800
committer Angie Chiang <angiebird@google.com> Tue Feb 27 17:32:24 2018 +0000
tree 3f9d166c1a666ddd2100d09a3cdcb72269c98665
parent f2f276c5ad8b97a492d74b4463de0b00feeaf978

Separate dc coeff decoding form others

BUG=aomedia:1369

Change-Id: Ibe104cfbc969728b2d5a2ffa38e954bce7fa98bc

av1/common/txb_common.h

diff --git a/av1/common/txb_common.h b/av1/common/txb_common.h
index 8443900..9c37324 100644
--- a/av1/common/txb_common.h
+++ b/av1/common/txb_common.h
@@ -360,6 +360,7 @@
 static INLINE int get_br_ctx_2d(const uint8_t *const levels,
                                 const int c,  // raster order
                                 const int bwl) {
+  assert(c > 0);
   const int row = c >> bwl;
   const int col = c - (row << bwl);
   const int stride = (1 << bwl) + TX_PAD_HOR;
@@ -369,7 +370,6 @@
       AOMMIN(levels[pos + stride], COEFF_BASE_RANGE + NUM_BASE_LEVELS + 1) +
       AOMMIN(levels[pos + 1 + stride], COEFF_BASE_RANGE + NUM_BASE_LEVELS + 1);
   mag = AOMMIN((mag + 1) >> 1, 6);
-  if (c == 0) return mag;
   if ((row < 2) && (col < 2)) return mag + 7;
   return mag + 14;
 }
@@ -537,6 +537,7 @@
 
 static INLINE int get_lower_levels_ctx_2d(const uint8_t *levels, int coeff_idx,
                                           int bwl, TX_SIZE tx_size) {
+  assert(coeff_idx > 0);
   int mag;
   // Note: AOMMIN(level, 3) is useless for decoder since level < 3.
   levels = levels + get_padded_idx(coeff_idx, bwl);
@@ -547,13 +548,9 @@
   mag += AOMMIN(levels[(2 << bwl) + (2 << TX_PAD_HOR_LOG2)], 3);  // { 2, 0 }
 
   const int ctx = AOMMIN((mag + 1) >> 1, 4);
-  if (!coeff_idx) {
-    return 0;
-  } else {
-    const int row = coeff_idx >> bwl;
-    const int col = coeff_idx - (row << bwl);
-    return ctx + av1_nz_map_ctx_offset[tx_size][AOMMIN(row, 4)][AOMMIN(col, 4)];
-  }
+  const int row = coeff_idx >> bwl;
+  const int col = coeff_idx - (row << bwl);
+  return ctx + av1_nz_map_ctx_offset[tx_size][AOMMIN(row, 4)][AOMMIN(col, 4)];
 }
 static INLINE int get_lower_levels_ctx(const uint8_t *levels, int coeff_idx,
                                        int bwl, TX_SIZE tx_size,

av1/decoder/decodetxb.c

diff --git a/av1/decoder/decodetxb.c b/av1/decoder/decodetxb.c
index acc2145..5f92a11 100644
--- a/av1/decoder/decodetxb.c
+++ b/av1/decoder/decodetxb.c
@@ -260,16 +260,20 @@
     }
     levels[get_padded_idx(pos, bwl)] = level;
   }
-  base_cdf_arr base_cdf = ec_ctx->coeff_base_cdf[txs_ctx][plane_type];
-  br_cdf_arr br_cdf =
-      ec_ctx->coeff_br_cdf[AOMMIN(txs_ctx, TX_32X32)][plane_type];
-  const TX_CLASS tx_class = tx_type_to_class[tx_type];
-  if (tx_class == TX_CLASS_2D) {
-    read_coeffs_reverse_2d(r, tx_size, 0, *eob - 1 - 1, scan, bwl, levels,
-                           base_cdf, br_cdf);
-  } else {
-    read_coeffs_reverse(r, tx_size, tx_type, 0, *eob - 1 - 1, scan, bwl, levels,
-                        base_cdf, br_cdf);
+  if (*eob > 1) {
+    base_cdf_arr base_cdf = ec_ctx->coeff_base_cdf[txs_ctx][plane_type];
+    br_cdf_arr br_cdf =
+        ec_ctx->coeff_br_cdf[AOMMIN(txs_ctx, TX_32X32)][plane_type];
+    const TX_CLASS tx_class = tx_type_to_class[tx_type];
+    if (tx_class == TX_CLASS_2D) {
+      read_coeffs_reverse_2d(r, tx_size, 1, *eob - 1 - 1, scan, bwl, levels,
+                             base_cdf, br_cdf);
+      read_coeffs_reverse(r, tx_size, tx_type, 0, 0, scan, bwl, levels,
+                          base_cdf, br_cdf);
+    } else {
+      read_coeffs_reverse(r, tx_size, tx_type, 0, *eob - 1 - 1, scan, bwl,
+                          levels, base_cdf, br_cdf);
+    }
   }
 
   // Loop to decode all signs in the transform block,