Tune vp9 quality scaler parameters

webrtc/modules/video_coding/utility/quality_scaler.cc

 /*
  *  Copyright (c) 2014 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 23 matching lines @@
 static const int kFramedropPercentThreshold = 60;
 // QP scaling threshold defaults:
 static const int kLowH264QpThreshold = 24;
 static const int kHighH264QpThreshold = 37;
 // QP is obtained from VP8-bitstream for HW, so the QP corresponds to the
 // bitstream range of [0, 127] and not the user-level range of [0,63].
 static const int kLowVp8QpThreshold = 29;
 static const int kHighVp8QpThreshold = 95;
 // QP is obtained from VP9-bitstream for HW, so the QP corresponds to the
 // bitstream range of [0, 255] and not the user-level range of [0,63].
 // Current VP9 settings are mapped from VP8 thresholds above.

[åsapersson, 2017/06/13 06:05:54]

maybe remove sentence above

 static const int kLowVp9QpThreshold = 96;
-static const int kHighVp9QpThreshold = 208;
+static const int kHighVp9QpThreshold = 185;
 static const int kMinFramesNeededToScale = 2 * 30;
 
 static VideoEncoder::QpThresholds CodecTypeToDefaultThresholds(
     VideoCodecType codec_type) {
   int low = -1;
   int high = -1;
   switch (codec_type) {
     case kVideoCodecH264:
       low = kLowH264QpThreshold;
       high = kHighH264QpThreshold;
@@ skipping 139 matching lines @@
     fast_rampup_ = false;
   }
 }
 
 void QualityScaler::ClearSamples() {
   RTC_DCHECK_CALLED_SEQUENTIALLY(&task_checker_);
   framedrop_percent_.Reset();
   average_qp_.Reset();
 }
 }  // namespace webrtc