VP9 codec controls for screensharing

webrtc/modules/video_coding/codecs/vp9/vp9_impl.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 386 matching lines @@
   // log2 unit: e.g., 0 = 1 tile column, 1 = 2 tile columns, 2 = 4 tile columns.
   // The number tile columns will be capped by the encoder based on image size
   // (minimum width of tile column is 256 pixels, maximum is 4096).
   vpx_codec_control(encoder_, VP9E_SET_TILE_COLUMNS, (config_->g_threads >> 1));
 #if !defined(WEBRTC_ARCH_ARM) && !defined(WEBRTC_ARCH_ARM64)
   // Note denoiser is still off by default until further testing/optimization,
   // i.e., codecSpecific.VP9.denoisingOn == 0.
   vpx_codec_control(encoder_, VP9E_SET_NOISE_SENSITIVITY,
                     inst->codecSpecific.VP9.denoisingOn ? 1 : 0);
 #endif
+  if (codec_.mode == kScreensharing) {
+    // Adjust internal parameters to screen content.
+    vpx_codec_control(encoder_, VP9E_SET_TUNE_CONTENT, 1);
+    // Let the encoder skip the encoding of very flat/low content blocks.

[stefan-webrtc, 2015/09/04 09:31:51]

As you say, we probably want to do this for regular content too. I think we
should evaluate if that helps.

AFAIK we are doing this for all content modes in VP8.

[ivica, 2015/09/04 09:40:41]

marpan@ told me to add this, and only for screensharing for now. We can easily
changed that later.

+    vpx_codec_control(encoder_, VP8E_SET_STATIC_THRESHOLD, 1);
+  }
+
   inited_ = true;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
 uint32_t VP9EncoderImpl::MaxIntraTarget(uint32_t optimal_buffer_size) {
   // Set max to the optimal buffer level (normalized by target BR),
   // and scaled by a scale_par.
   // Max target size = scale_par * optimal_buffer_size * targetBR[Kbps].
   // This value is presented in percentage of perFrameBw:
   // perFrameBw = targetBR[Kbps] * 1000 / framerate.
@@ skipping 359 matching lines @@
     decoder_ = NULL;
   }
   // Releases buffers from the pool. Any buffers not in use are deleted. Buffers
   // still referenced externally are deleted once fully released, not returning
   // to the pool.
   frame_buffer_pool_.ClearPool();
   inited_ = false;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 }  // namespace webrtc