[CFL] drop skip logic, always write alpha

Results on Subset 1 (Compared to a0f8c145 with CfL)

  PSNR | PSNR Cb | PSNR Cr | PSNR HVS |   SSIM | MS SSIM | CIEDE 2000
0.0677 | -0.3359 | -0.2115 |   0.0529 | 0.0735 |  0.0495 |    -0.0907

Change-Id: Ib61ff862e8cfbdf0c693a4eba5f2712a6e9ab819
Signed-off-by: David Michael Barr <b@rr-dav.id.au>

av1/common/cfl.h

@@ -42,11 +42,6 @@ typedef struct {
 
   // The rate associated with each alpha codeword
   int costs[CFL_ALPHABET_SIZE];
-
-  // Count the number of TX blocks in a predicted block to know when you are at
-  // the last one, so you can check for skips.
-  // TODO(any) Is there a better way to do this?
-  int num_tx_blk[CFL_PRED_PLANES];
 } CFL_CTX;
 
 static const double cfl_alpha_mags[CFL_MAGS_SIZE] = {

av1/decoder/decodemv.c

@@ -161,27 +161,21 @@ static PREDICTION_MODE read_intra_mode_uv(FRAME_CONTEXT *ec_ctx,
 }
 
 #if CONFIG_CFL
-static int read_cfl_alphas(FRAME_CONTEXT *const ec_ctx, aom_reader *r, int skip,
+static int read_cfl_alphas(FRAME_CONTEXT *const ec_ctx, aom_reader *r,
                            CFL_SIGN_TYPE signs_out[CFL_PRED_PLANES]) {
-  if (skip) {
-    signs_out[CFL_PRED_U] = CFL_SIGN_POS;
-    signs_out[CFL_PRED_V] = CFL_SIGN_POS;
-    return 0;
-  } else {
-    const int ind = aom_read_symbol(r, ec_ctx->cfl_alpha_cdf, CFL_ALPHABET_SIZE,
-                                    "cfl:alpha");
-    // Signs are only coded for nonzero values
-    // sign == 0 implies negative alpha
-    // sign == 1 implies positive alpha
-    signs_out[CFL_PRED_U] = cfl_alpha_codes[ind][CFL_PRED_U]
-                                ? aom_read_bit(r, "cfl:sign")
-                                : CFL_SIGN_POS;
-    signs_out[CFL_PRED_V] = cfl_alpha_codes[ind][CFL_PRED_V]
-                                ? aom_read_bit(r, "cfl:sign")
-                                : CFL_SIGN_POS;
-
-    return ind;
-  }
+  const int ind =
+      aom_read_symbol(r, ec_ctx->cfl_alpha_cdf, CFL_ALPHABET_SIZE, "cfl:alpha");
+  // Signs are only coded for nonzero values
+  // sign == 0 implies negative alpha
+  // sign == 1 implies positive alpha
+  signs_out[CFL_PRED_U] = cfl_alpha_codes[ind][CFL_PRED_U]
+                              ? aom_read_bit(r, "cfl:sign")
+                              : CFL_SIGN_POS;
+  signs_out[CFL_PRED_V] = cfl_alpha_codes[ind][CFL_PRED_V]
+                              ? aom_read_bit(r, "cfl:sign")
+                              : CFL_SIGN_POS;
+
+  return ind;
 }
 #endif
 
@@ -1158,8 +1152,7 @@ static void read_intra_frame_mode_info(AV1_COMMON *const cm,
 #if CONFIG_CFL
     // TODO(ltrudeau) support PALETTE
     if (mbmi->uv_mode == DC_PRED) {
-      mbmi->cfl_alpha_idx =
-          read_cfl_alphas(ec_ctx, r, mbmi->skip, mbmi->cfl_alpha_signs);
+      mbmi->cfl_alpha_idx = read_cfl_alphas(ec_ctx, r, mbmi->cfl_alpha_signs);
     }
 #endif  // CONFIG_CFL
 
@@ -1654,7 +1647,7 @@ static void read_intra_block_mode_info(AV1_COMMON *const cm, const int mi_row,
 #else
           cm->fc,
 #endif  // CONFIG_EC_ADAPT
-          r, mbmi->skip, mbmi->cfl_alpha_signs);
+          r, mbmi->cfl_alpha_signs);
     }
 #endif  // CONFIG_CFL
 

av1/encoder/bitstream.c

@@ -1813,29 +1813,23 @@ static void write_intra_uv_mode(FRAME_CONTEXT *frame_ctx,
 }
 
 #if CONFIG_CFL
-static void write_cfl_alphas(FRAME_CONTEXT *const frame_ctx, int skip, int ind,
+static void write_cfl_alphas(FRAME_CONTEXT *const frame_ctx, int ind,
                              const CFL_SIGN_TYPE signs[CFL_SIGNS],
                              aom_writer *w) {
-  if (skip) {
-    assert(ind == 0);
+  // Check for uninitialized signs
+  if (cfl_alpha_codes[ind][CFL_PRED_U] == 0)
     assert(signs[CFL_PRED_U] == CFL_SIGN_POS);
+  if (cfl_alpha_codes[ind][CFL_PRED_V] == 0)
     assert(signs[CFL_PRED_V] == CFL_SIGN_POS);
-  } else {
-    // Check for uninitialized signs
-    if (cfl_alpha_codes[ind][CFL_PRED_U] == 0)
-      assert(signs[CFL_PRED_U] == CFL_SIGN_POS);
-    if (cfl_alpha_codes[ind][CFL_PRED_V] == 0)
-      assert(signs[CFL_PRED_V] == CFL_SIGN_POS);
 
-    // Write a symbol representing a combination of alpha Cb and alpha Cr.
-    aom_write_symbol(w, ind, frame_ctx->cfl_alpha_cdf, CFL_ALPHABET_SIZE);
+  // Write a symbol representing a combination of alpha Cb and alpha Cr.
+  aom_write_symbol(w, ind, frame_ctx->cfl_alpha_cdf, CFL_ALPHABET_SIZE);
 
-    // Signs are only signaled for nonzero codes.
-    if (cfl_alpha_codes[ind][CFL_PRED_U] != 0)
-      aom_write_bit(w, signs[CFL_PRED_U]);
-    if (cfl_alpha_codes[ind][CFL_PRED_V] != 0)
-      aom_write_bit(w, signs[CFL_PRED_V]);
-  }
+  // Signs are only signaled for nonzero codes.
+  if (cfl_alpha_codes[ind][CFL_PRED_U] != 0)
+    aom_write_bit(w, signs[CFL_PRED_U]);
+  if (cfl_alpha_codes[ind][CFL_PRED_V] != 0)
+    aom_write_bit(w, signs[CFL_PRED_V]);
 }
 #endif
 
@@ -1987,8 +1981,7 @@ static void pack_inter_mode_mvs(AV1_COMP *cpi, const int mi_row,
 
 #if CONFIG_CFL
       if (mbmi->uv_mode == DC_PRED) {
-        write_cfl_alphas(ec_ctx, mbmi->skip, mbmi->cfl_alpha_idx,
-                         mbmi->cfl_alpha_signs, w);
+        write_cfl_alphas(ec_ctx, mbmi->cfl_alpha_idx, mbmi->cfl_alpha_signs, w);
       }
 #endif
 
@@ -2390,8 +2383,7 @@ static void write_mb_modes_kf(AV1_COMMON *cm,
 
 #if CONFIG_CFL
     if (mbmi->uv_mode == DC_PRED) {
-      write_cfl_alphas(ec_ctx, mbmi->skip, mbmi->cfl_alpha_idx,
-                       mbmi->cfl_alpha_signs, w);
+      write_cfl_alphas(ec_ctx, mbmi->cfl_alpha_idx, mbmi->cfl_alpha_signs, w);
     }
 #endif
 

av1/encoder/encodemb.c

@@ -1443,53 +1443,9 @@ void av1_encode_block_intra(int plane, int block, int blk_row, int blk_col,
 // Note : *(args->skip) == mbmi->skip
 #endif
 #if CONFIG_CFL
-  MB_MODE_INFO *mbmi = &xd->mi[0]->mbmi;
   if (plane == AOM_PLANE_Y && x->cfl_store_y) {
     cfl_store(xd->cfl, dst, dst_stride, blk_row, blk_col, tx_size);
   }
-
-  if (mbmi->uv_mode == DC_PRED) {
-    // TODO(ltrudeau) find a cleaner way to detect last transform block
-    if (plane == AOM_PLANE_U) {
-      xd->cfl->num_tx_blk[CFL_PRED_U] =
-          (blk_row == 0 && blk_col == 0) ? 1
-                                         : xd->cfl->num_tx_blk[CFL_PRED_U] + 1;
-    }
-
-    if (plane == AOM_PLANE_V) {
-      xd->cfl->num_tx_blk[CFL_PRED_V] =
-          (blk_row == 0 && blk_col == 0) ? 1
-                                         : xd->cfl->num_tx_blk[CFL_PRED_V] + 1;
-
-      if (mbmi->skip &&
-          xd->cfl->num_tx_blk[CFL_PRED_U] == xd->cfl->num_tx_blk[CFL_PRED_V]) {
-        assert(plane_bsize != BLOCK_INVALID);
-        const int block_width = block_size_wide[plane_bsize];
-        const int block_height = block_size_high[plane_bsize];
-
-        // if SKIP is chosen at the block level, and ind != 0, we must change
-        // the prediction
-        if (mbmi->cfl_alpha_idx != 0) {
-          const struct macroblockd_plane *const pd_cb = &xd->plane[AOM_PLANE_U];
-          uint8_t *const dst_cb = pd_cb->dst.buf;
-          const int dst_stride_cb = pd_cb->dst.stride;
-          uint8_t *const dst_cr = pd->dst.buf;
-          const int dst_stride_cr = pd->dst.stride;
-          for (int j = 0; j < block_height; j++) {
-            for (int i = 0; i < block_width; i++) {
-              dst_cb[dst_stride_cb * j + i] =
-                  (uint8_t)(xd->cfl->dc_pred[CFL_PRED_U] + 0.5);
-              dst_cr[dst_stride_cr * j + i] =
-                  (uint8_t)(xd->cfl->dc_pred[CFL_PRED_V] + 0.5);
-            }
-          }
-          mbmi->cfl_alpha_idx = 0;
-          mbmi->cfl_alpha_signs[CFL_PRED_U] = CFL_SIGN_POS;
-          mbmi->cfl_alpha_signs[CFL_PRED_V] = CFL_SIGN_POS;
-        }
-      }
-    }
-  }
 #endif
 }