libvpx: Pull from upstream

source/libvpx/vp8/encoder/ethreading.c

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 188 matching lines @@
                         {
                             int b;
 
                             for (b = 0; b < xd->mbmi.partition_count; b++)
                             {
                                 inter_b_modes[x->partition->bmi[b].mode] ++;
                             }
                         }
 
 #endif
+                        // Keep track of how many (consecutive) times a  block
+                        // is coded as ZEROMV_LASTREF, for base layer frames.
+                        // Reset to 0 if its coded as anything else.
+                        if (cpi->current_layer == 0) {
+                          if (xd->mode_info_context->mbmi.mode == ZEROMV &&
+                              xd->mode_info_context->mbmi.ref_frame ==
+                                  LAST_FRAME) {
+                            // Increment, check for wrap-around.
+                            if (cpi->consec_zero_last[map_index+mb_col] < 255)
+                              cpi->consec_zero_last[map_index+mb_col] +=
+                                  1;
+                          } else {
+                            cpi->consec_zero_last[map_index+mb_col] = 0;
+                          }
+                        }
 
                         /* Special case code for cyclic refresh
                          * If cyclic update enabled then copy
                          * xd->mbmi.segment_id; (which may have been updated
                          * based on mode during
                          * vp8cx_encode_inter_macroblock()) back into the
                          * global segmentation map
                          */
                         if ((cpi->current_layer == 0) &&
                             (cpi->cyclic_refresh_mode_enabled &&
@@ skipping 427 matching lines @@
         sem_destroy(&cpi->h_event_start_lpf);
 
         /* free thread related resources */
         vpx_free(cpi->h_event_start_encoding);
         vpx_free(cpi->h_encoding_thread);
         vpx_free(cpi->mb_row_ei);
         vpx_free(cpi->en_thread_data);
     }
 }
 #endif