Implement a high-QP threshold for Android H.264.

talk/app/webrtc/java/jni/androidmediaencoder_jni.cc

 /*
  * libjingle
  * Copyright 2015 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
@@ skipping 288 matching lines @@
   scale_ = webrtc::field_trial::FindFullName(
       "WebRTC-MediaCodecVideoEncoder-AutomaticResize") == "Enabled";
   ALOGD("Automatic resize: %s", scale_ ? "enabled" : "disabled");
   if (scale_) {
     if (codecType_ == kVideoCodecVP8) {
       // QP is obtained from VP8-bitstream for HW, so the QP corresponds to the
       // (internal) range: [0, 127]. And we cannot change QP_max in HW, so it is
       // always = 127. Note that in SW, QP is that of the user-level range [0,
       // 63].
       const int kMaxQp = 127;
-      quality_scaler_.Init(kMaxQp / kLowQpThresholdDenominator, true);
+      // TODO(pbos): Investigate whether high-QP thresholds make sense for VP8.
+      // This effectively disables high QP as VP8 QP can't go above this
+      // threshold.
+      const int kDisabledBadQpThreshold = kMaxQp + 1;
+      quality_scaler_.Init(kMaxQp / kLowQpThresholdDenominator,
+                           kDisabledBadQpThreshold, true);
     } else if (codecType_ == kVideoCodecH264) {
       // H264 QP is in the range [0, 51].
       const int kMaxQp = 51;
-      quality_scaler_.Init(kMaxQp / kLowQpThresholdDenominator, true);
+      const int kBadQpThreshold = 40;
+      quality_scaler_.Init(kMaxQp / kLowQpThresholdDenominator, kBadQpThreshold,
+                           false);
     } else {
       // When adding codec support to additional hardware codecs, also configure
       // their QP thresholds for scaling.
       RTC_NOTREACHED() << "Unsupported codec without configured QP thresholds.";
     }
     quality_scaler_.SetMinResolution(kMinWidth, kMinHeight);
     quality_scaler_.ReportFramerate(codec_settings->maxFramerate);
   }
   return codec_thread_->Invoke<int32_t>(
       Bind(&MediaCodecVideoEncoder::InitEncodeOnCodecThread,
@@ skipping 618 matching lines @@
 }
 
 void MediaCodecVideoEncoderFactory::DestroyVideoEncoder(
     webrtc::VideoEncoder* encoder) {
   ALOGD("Destroy video encoder.");
   delete encoder;
 }
 
 }  // namespace webrtc_jni