Tune QP-based quality thresholds.

webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc

 /*
  *  Copyright (c) 2012 The WebRTC 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 586 matching lines @@
     }
   }
 
   rps_.Init();
   // Disable both high-QP limits and framedropping. Both are handled by libvpx
   // internally.
   // QP thresholds are chosen to be high enough to be hit in practice when
   // quality is good, but also low enough to not cause a flip-flop behavior
   // (e.g. going up in resolution shouldn't give so bad quality that we should
   // go back down).
-  const int kLowQpThreshold = 23;
-  const int kDisabledBadQpThreshold = 128;
+  const int kLowQpThreshold = 29;
+  const int kDisabledBadQpThreshold = 100;
   // TODO(glaznev/sprang): consider passing codec initial bitrate to quality
   // scaler to avoid starting with HD for low initial bitrates.
   quality_scaler_.Init(kLowQpThreshold, kDisabledBadQpThreshold, false, 0, 0, 0,
                        codec_.maxFramerate);
 
   // Only apply scaling to improve for single-layer streams. The scaling metrics
   // use frame drops as a signal and is only applicable when we drop frames.
   quality_scaler_enabled_ = encoders_.size() == 1 &&
                             configurations_[0].rc_dropframe_thresh > 0 &&
                             codec_.codecSpecific.VP8.automaticResizeOn;
@@ skipping 794 matching lines @@
     return -1;
   }
   if (vpx_codec_control(copy->decoder_, VP8_SET_REFERENCE, ref_frame_) !=
       VPX_CODEC_OK) {
     return -1;
   }
   return 0;
 }
 
 }  // namespace webrtc