Work on flexible mode and screen sharing.

webrtc/modules/video_coding/codecs/vp9/screenshare_layers.cc

Index: webrtc/modules/video_coding/codecs/vp9/screenshare_layers.cc
diff --git a/webrtc/modules/video_coding/codecs/vp9/screenshare_layers.cc b/webrtc/modules/video_coding/codecs/vp9/screenshare_layers.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ecf0ffe16f846aa429a7ac406105f95bc3cd172c
--- /dev/null
+++ b/webrtc/modules/video_coding/codecs/vp9/screenshare_layers.cc
@@ -0,0 +1,64 @@
+/* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.

[sprang_webrtc, 2015/09/15 15:41:21]

2015

[philipel, 2015/09/16 09:35:53]

Done.

+*
+*  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.
+*/
+
+#include <algorithm>
+#include "webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h"
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+ScreenshareLayersVP9::ScreenshareLayersVP9()
+    : threshold_kbps_(0.f),
+      l0_bits_used_(0.f),
+      last_ts_(0),
+      current_layer_(0) {}
+
+int ScreenshareLayersVP9::CurrentLayer() const {
+  return current_layer_;
+}
+
+void ScreenshareLayersVP9::ConfigureBitrate(int threshold_kbps) {
+  threshold_kbps_ = threshold_kbps;
+}
+
+void ScreenshareLayersVP9::LayerFrameEncoded(unsigned int size_bytes,
+                                             int layer_id) {
+  if (layer_id == 0) {
+    l0_bits_used_ += size_bytes * 8;
+  }

[sprang_webrtc, 2015/09/15 15:41:21]

remove {}

[philipel, 2015/09/16 09:35:53]

Done.

+}
+
+VP9EncoderImpl::SuperFrameRefSettings ScreenshareLayersVP9::SfSettings(
+    uint32_t timestamp,
+    bool is_keyframe) {
+  VP9EncoderImpl::SuperFrameRefSettings res;
+  res.stop_layer = 1;
+  res.layer[0].upd_buf = 0;
+  res.layer[0].ref_buf1 = 0;
+  res.layer[1].upd_buf = 1;
+  res.layer[1].ref_buf1 = 1;
+  res.is_keyframe = is_keyframe;
+  if (last_ts_ == 0 || is_keyframe) {
+    res.start_layer = 0;
+  } else {
+    float diff = timestamp - last_ts_;
+    l0_bits_used_ =
+        std::max(0.f, l0_bits_used_ - diff / 90.f * threshold_kbps_);
+    if (l0_bits_used_ > threshold_kbps_ * 1000 && !is_keyframe) {

[sprang_webrtc, 2015/09/15 15:41:21]

is_keyframe should always be false here?

[philipel, 2015/09/16 09:35:53]

If it is a keyframe then we must encode both layers.

[sprang_webrtc, 2015/09/25 09:53:15]

I was more referring to the fact that if is_keyframe was true then would have
entered the if on line 47, and not ended up here. But is notice this has changed
now so nevermind :)

+      res.start_layer = 1;
+    } else {
+      res.start_layer = 0;
+    }
+  }

[sprang_webrtc, 2015/09/15 15:41:21]

As noted in a previous comment, this measures average bitrate since the first
frame - but the bitrate can dynamically change...
I think you can bring over some parts of screenshare_layers for vp8 related to
this (minus the qp boost things etc)

[philipel, 2015/09/16 09:35:53]

It is NOT true that it measures the average bitrate since the first frame. If
the threshold_kbps_ change than so does the rate at which l0_bits_used_ is
decreased.

[sprang_webrtc, 2015/09/25 09:53:15]

Ah, you're right.

+  current_layer_ = res.start_layer;
+  last_ts_ = timestamp;
+  return res;
+}
+
+}  // namespace webrtc