Move the QP scaling thresholds to the relevant encoders

webrtc/modules/video_coding/utility/quality_scaler.cc

Index: webrtc/modules/video_coding/utility/quality_scaler.cc
diff --git a/webrtc/modules/video_coding/utility/quality_scaler.cc b/webrtc/modules/video_coding/utility/quality_scaler.cc
index 7ef7c575ba4b699210fca7c4e40f0b557a54d440..0696bbbf705b60c4e34d246c0d402d3d7b504e09 100644
--- a/webrtc/modules/video_coding/utility/quality_scaler.cc
+++ b/webrtc/modules/video_coding/utility/quality_scaler.cc
@@ -14,6 +14,8 @@
 
 #include <algorithm>
 
+#include "webrtc/base/checks.h"
+
 // TODO(kthelgason): Some versions of Android have issues with log2.
 // See https://code.google.com/p/android/issues/detail?id=212634 for details
 #if defined(WEBRTC_ANDROID)
@@ -38,22 +40,15 @@ static const int kVgaBitrateThresholdKbps = 500;
 static const int kVgaNumPixels = 700 * 500;  // 640x480
 static const int kQvgaBitrateThresholdKbps = 250;
 static const int kQvgaNumPixels = 400 * 300;  // 320x240
-}  // namespace
-
-// 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 QualityScaler::kLowVp8QpThreshold = 29;
-const int QualityScaler::kBadVp8QpThreshold = 95;
 
-#if defined(WEBRTC_IOS)
-const int QualityScaler::kLowH264QpThreshold = 32;
-const int QualityScaler::kBadH264QpThreshold = 42;
-#else
-const int QualityScaler::kLowH264QpThreshold = 24;
-const int QualityScaler::kBadH264QpThreshold = 37;
-#endif
+// QP scaling threshold defaults:
+static const int kLowH264QpThreshold = 28;
+static const int kHighH264QpThreshold = 39;
+// 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;
+}  // namespace
 
 // Default values. Should immediately get set to something more sensible.
 QualityScaler::QualityScaler()
@@ -61,14 +56,24 @@ QualityScaler::QualityScaler()
       framedrop_percent_(kMeasureSecondsUpscale * 30),
       low_qp_threshold_(-1) {}
 
-void QualityScaler::Init(int low_qp_threshold,
-                         int high_qp_threshold,
+void QualityScaler::Init(VideoCodecType codec_type,
                          int initial_bitrate_kbps,
                          int width,
                          int height,
                          int fps) {
-  low_qp_threshold_ = low_qp_threshold;
-  high_qp_threshold_ = high_qp_threshold;
+  ClearSamples();

[pbos-webrtc, 2016/09/19 14:06:57]

Have this function just get low/high thresholds and then call the other Init
function with found high/low parameters.

E.g. this function just gets the default parameters for QP, then forwards to the
other Init().

+  switch (codec_type) {
+    case kVideoCodecH264:
+      low_qp_threshold_ = kLowH264QpThreshold;
+      high_qp_threshold_ = kHighH264QpThreshold;
+      break;
+    case kVideoCodecVP8:
+      low_qp_threshold_ = kLowVp8QpThreshold;
+      high_qp_threshold_ = kHighVp8QpThreshold;
+      break;
+    default:
+      RTC_NOTREACHED() << "Invalid codec type for QualityScaler.";
+  }
   downscale_shift_ = 0;
 
   fast_rampup_ = true;
@@ -94,6 +99,18 @@ void QualityScaler::Init(int low_qp_threshold,
   ReportFramerate(fps);
 }
 
+void QualityScaler::Init(VideoCodecType codec_type,
+                         int initial_bitrate_kbps,
+                         int width,
+                         int height,
+                         int fps,
+                         int highQpThreshold,

[pbos-webrtc, 2016/09/19 14:06:57]

high_qp_threshold, same for low

+                         int lowQpThreshold) {
+  Init(codec_type, initial_bitrate_kbps, width, height, fps);
+  low_qp_threshold_ = highQpThreshold;
+  high_qp_threshold_ = lowQpThreshold;
+}
+
 // Report framerate(fps) to estimate # of samples.
 void QualityScaler::ReportFramerate(int framerate) {
   // Use a faster window for upscaling initially.