libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_picklpf.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 126 matching lines @@
 }
 
 void vp9_pick_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
                            LPF_PICK_METHOD method) {
   VP9_COMMON *const cm = &cpi->common;
   struct loopfilter *const lf = &cm->lf;
 
   lf->sharpness_level = cm->frame_type == KEY_FRAME ? 0
                                                     : cpi->oxcf.sharpness;
 
-  if (method == LPF_PICK_FROM_Q) {
+  if (method == LPF_PICK_MINIMAL_LPF && lf->filter_level) {
+      lf->filter_level = 0;
+  } else if (method >= LPF_PICK_FROM_Q) {
     const int min_filter_level = 0;
     const int max_filter_level = get_max_filter_level(cpi);
     const int q = vp9_ac_quant(cm->base_qindex, 0);
     // These values were determined by linear fitting the result of the
     // searched level, filt_guess = q * 0.316206 + 3.87252
     int filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 1015158, 18);
     if (cm->frame_type == KEY_FRAME)
       filt_guess -= 4;
     lf->filter_level = clamp(filt_guess, min_filter_level, max_filter_level);
   } else {
     lf->filter_level = search_filter_level(sd, cpi,
                                            method == LPF_PICK_FROM_SUBIMAGE);
   }
 }