Remove limit on how often quality scaling downscales.

webrtc/video/vie_encoder.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 14 matching lines @@
 #include "webrtc/modules/video_coding/include/video_coding_defines.h"
 #include "webrtc/video/overuse_frame_detector.h"
 #include "webrtc/video/send_statistics_proxy.h"
 #include "webrtc/video_frame.h"
 
 namespace webrtc {
 
 namespace {
 // Time interval for logging frame counts.
 const int64_t kFrameLogIntervalMs = 60000;
+// We will never ask for a resolution lower than this.
+const int kMinPixelsPerFrame = 120 * 90;
 
 // TODO(pbos): Lower these thresholds (to closer to 100%) when we handle
 // pipelining encoders better (multiple input frames before something comes
 // out). This should effectively turn off CPU adaptations for systems that
 // remotely cope with the load right now.
 CpuOveruseOptions GetCpuOveruseOptions(bool full_overuse_time) {
   CpuOveruseOptions options;
   if (full_overuse_time) {
     options.low_encode_usage_threshold_percent = 150;
     options.high_encode_usage_threshold_percent = 200;
@@ skipping 124 matching lines @@
     rtc::CritScope lock(&crit_);
     if (!IsResolutionScalingEnabledLocked()) {
       // This can happen since |degradation_preference_| is set on
       // libjingle's worker thread but the adaptation is done on the encoder
       // task queue.
       return;
     }
     // The input video frame size will have a resolution with less than or
     // equal to |max_pixel_count| depending on how the source can scale the
     // input frame size.
-    sink_wants_.max_pixel_count = rtc::Optional<int>((pixel_count * 3) / 5);
+    const int pixels_wanted = (pixel_count * 3) / 5;
+    if (pixels_wanted < kMinPixelsPerFrame)
+      return;
+    sink_wants_.max_pixel_count = rtc::Optional<int>(pixels_wanted);
     sink_wants_.max_pixel_count_step_up = rtc::Optional<int>();
     if (source_)
       source_->AddOrUpdateSink(vie_encoder_, sink_wants_);
   }
 
   void RequestHigherResolutionThan(int pixel_count) {
     rtc::CritScope lock(&crit_);
     if (!IsResolutionScalingEnabledLocked()) {
       // This can happen since |degradation_preference_| is set on
       // libjingle's worker thread but the adaptation is done on the encoder
@@ skipping 484 matching lines @@
   RTC_DCHECK_RUN_ON(&encoder_queue_);
   if (!scaling_enabled_)
     return;
   // Request lower resolution if the current resolution is lower than last time
   // we asked for the resolution to be lowered.
   int current_pixel_count = last_frame_height_ * last_frame_width_;
   if (max_pixel_count_ && current_pixel_count >= *max_pixel_count_)
     return;
   switch (reason) {
     case kQuality:
-      if (scale_counter_[reason] >= kMaxQualityDowngrades)
-        return;
       stats_proxy_->OnQualityRestrictedResolutionChanged(true);
       break;
     case kCpu:
       if (scale_counter_[reason] >= kMaxCpuDowngrades)
         return;
       // Update stats accordingly.
       stats_proxy_->OnCpuRestrictedResolutionChanged(true);
       break;
   }
   max_pixel_count_ = rtc::Optional<int>(current_pixel_count);
@@ skipping 32 matching lines @@
   --scale_counter_[reason];
   source_proxy_->RequestHigherResolutionThan(current_pixel_count);
   LOG(LS_INFO) << "Scaling up resolution.";
   for (size_t i = 0; i < kScaleReasonSize; ++i) {
     LOG(LS_INFO) << "Scaled " << scale_counter_[i]
                  << " times for reason: " << (i ? "quality" : "cpu");
   }
 }
 
 }  // namespace webrtc