MediaRecorder: Tune complexity settings for VP9 encoding

content/renderer/media/video_track_recorder.cc

Index: content/renderer/media/video_track_recorder.cc
diff --git a/content/renderer/media/video_track_recorder.cc b/content/renderer/media/video_track_recorder.cc
index 82ae3ea9ba7dc9ed25e19f9277f1e0fd758de253..b9d2e0f72d4c5aa68d1952d6a6a6054c17f5ed78 100644
--- a/content/renderer/media/video_track_recorder.cc
+++ b/content/renderer/media/video_track_recorder.cc
@@ -260,9 +260,8 @@ void VideoTrackRecorder::VpxEncoder::ConfigureEncoding(const gfx::Size& size) {
 
   const vpx_codec_iface_t* interface =
       use_vp9_ ? vpx_codec_vp9_cx() : vpx_codec_vp8_cx();
-  const vpx_codec_err_t result = vpx_codec_enc_config_default(interface,
-                                                              &codec_config_,
-                                                              0 /* reserved */);
+  vpx_codec_err_t result =
+      vpx_codec_enc_config_default(interface, &codec_config_, 0 /* reserved */);
   DCHECK_EQ(VPX_CODEC_OK, result);
 
   DCHECK_EQ(320u, codec_config_.g_w);
@@ -325,6 +324,17 @@ void VideoTrackRecorder::VpxEncoder::ConfigureEncoding(const gfx::Size& size) {
   const vpx_codec_err_t ret = vpx_codec_enc_init(encoder_.get(), interface,
                                                  &codec_config_, kNoFlags);
   DCHECK_EQ(VPX_CODEC_OK, ret);
+
+  if (use_vp9_) {
+    // Values of VP8E_SET_CPUUSED greater than 0 will increase encoder speed at
+    // the expense of quality up to a maximum value of 8 for VP9, by tuning the
+    // target time spent encoding the frame. Go from 8 to 5 (values for real
+    // time encoding) depending on the amount of cores available in the system.
+    const int kCpuUsed =
+        std::max(5, 8 - base::SysInfo::NumberOfProcessors() / 2);
+    result = vpx_codec_control(encoder_.get(), VP8E_SET_CPUUSED, kCpuUsed);
+    DLOG_IF(WARNING, VPX_CODEC_OK != result) << "VP8E_SET_CPUUSED failed";
+  }
 }
 
 bool VideoTrackRecorder::VpxEncoder::IsInitialized() const {