Make sure we observe enough frames before scaling.

webrtc/modules/video_coding/utility/quality_scaler_unittest.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 113 matching lines @@
 
 TEST_F(QualityScalerTest, DownscalesAboveHighQp) {
   DO_SYNC(q_, { TriggerScale(kScaleDownAboveHighQp); });
   EXPECT_TRUE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(1, observer_->adapt_down_events_);
   EXPECT_EQ(0, observer_->adapt_up_events_);
 }
 
 TEST_F(QualityScalerTest, DownscalesAfterTwoThirdsFramedrop) {
   DO_SYNC(q_, {
-    qs_->ReportDroppedFrame();
-    qs_->ReportDroppedFrame();
-    qs_->ReportQP(kHighQp);
+    for (int i = 0; i < kFramerate * 5; ++i) {
+      qs_->ReportDroppedFrame();
+      qs_->ReportDroppedFrame();
+      qs_->ReportQP(kHighQp);
+    }
   });
   EXPECT_TRUE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(1, observer_->adapt_down_events_);
   EXPECT_EQ(0, observer_->adapt_up_events_);
 }
 
 TEST_F(QualityScalerTest, DoesNotDownscaleOnNormalQp) {
   DO_SYNC(q_, { TriggerScale(kScaleDownAboveHighQp); });
   EXPECT_TRUE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(1, observer_->adapt_down_events_);
   EXPECT_EQ(0, observer_->adapt_up_events_);
 }
 

[magjed_webrtc, 2017/03/30 11:15:02]

Can you add a test targeting the specific issue, i.e. that we don't downscale
based on too few frames?

[kthelgason, 2017/03/31 08:12:58]

Good point, done.

 TEST_F(QualityScalerTest, DoesNotDownscaleAfterHalfFramedrop) {
   DO_SYNC(q_, {
-    qs_->ReportDroppedFrame();
-    qs_->ReportQP(kHighQp);
+    for (int i = 0; i < kFramerate * 5; ++i) {
+      qs_->ReportDroppedFrame();
+      qs_->ReportQP(kHighQp);
+    }
   });
   EXPECT_FALSE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(0, observer_->adapt_down_events_);
   EXPECT_EQ(0, observer_->adapt_up_events_);
 }
 
 TEST_F(QualityScalerTest, UpscalesAfterLowQp) {
   DO_SYNC(q_, { TriggerScale(kScaleUp); });
   EXPECT_TRUE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(0, observer_->adapt_down_events_);
   EXPECT_EQ(1, observer_->adapt_up_events_);
 }
 
 TEST_F(QualityScalerTest, ScalesDownAndBackUp) {
   DO_SYNC(q_, { TriggerScale(kScaleDown); });
   EXPECT_TRUE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(1, observer_->adapt_down_events_);
   EXPECT_EQ(0, observer_->adapt_up_events_);
   DO_SYNC(q_, { TriggerScale(kScaleUp); });
   EXPECT_TRUE(observer_->event.Wait(kDefaultTimeoutMs));
   EXPECT_EQ(1, observer_->adapt_down_events_);
   EXPECT_EQ(1, observer_->adapt_up_events_);
 }
 }  // namespace webrtc
 #undef DO_SYNC