Change rtc::VideoSinkWants to have target and a max pixel count

webrtc/media/base/videobroadcaster.cc

 /*
  *  Copyright (c) 2016 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 71 matching lines @@
     // wants.rotation_applied == ANY(sink.wants.rotation_applied)
     if (sink.wants.rotation_applied) {
       wants.rotation_applied = true;
     }
     // wants.max_pixel_count == MIN(sink.wants.max_pixel_count)
     if (sink.wants.max_pixel_count &&
         (!wants.max_pixel_count ||
          (*sink.wants.max_pixel_count < *wants.max_pixel_count))) {
       wants.max_pixel_count = sink.wants.max_pixel_count;
     }
-    // wants.max_pixel_count_step_up == MIN(sink.wants.max_pixel_count_step_up)
-    if (sink.wants.max_pixel_count_step_up &&
-        (!wants.max_pixel_count_step_up ||
-         (*sink.wants.max_pixel_count_step_up <
-          *wants.max_pixel_count_step_up))) {
-      wants.max_pixel_count_step_up = sink.wants.max_pixel_count_step_up;
+    // Select the minimum requested target_pixel_count, if any, of all sinks so

[nisse-webrtc, 2017/02/06 08:43:19]

Sinks could use max_pixel_count to express a limit. So one could use average or
median instead of minimum, right?

Probably best to stick to minimum for now, though, if that's closest to the old
behavior.

Ultimately, we'd like to support separate dimensions for each sink, possibly
pushing actual scaling further down the pipeline.

[sprang_webrtc, 2017/02/06 10:34:02]

I wasn't aware of the full context of this behavior so tried to stick close to
the previous behavior.
Agree that it could make sense to do something "smarter" if we can express the
limit with max, but let's not do that in another cl in that case. I'll add a
todo.

+    // that we don't over utilize the resources for any one.
+    if (sink.wants.target_pixel_count &&
+        (!wants.target_pixel_count ||
+         (*sink.wants.target_pixel_count < *wants.target_pixel_count))) {
+      wants.target_pixel_count = sink.wants.target_pixel_count;
     }
   }
 
-  if (wants.max_pixel_count && wants.max_pixel_count_step_up &&
-      *wants.max_pixel_count_step_up >= *wants.max_pixel_count) {
-    wants.max_pixel_count_step_up = Optional<int>();
+  if (wants.max_pixel_count && wants.target_pixel_count &&
+      *wants.target_pixel_count >= *wants.max_pixel_count) {
+    wants.target_pixel_count = wants.max_pixel_count;
   }
   current_wants_ = wants;
 }
 
 const rtc::scoped_refptr<webrtc::VideoFrameBuffer>&
 VideoBroadcaster::GetBlackFrameBuffer(int width, int height) {
   if (!black_frame_buffer_ || black_frame_buffer_->width() != width ||
       black_frame_buffer_->height() != height) {
     rtc::scoped_refptr<webrtc::I420Buffer> buffer =
         webrtc::I420Buffer::Create(width, height);
     webrtc::I420Buffer::SetBlack(buffer.get());
     black_frame_buffer_ = buffer;
   }
 
   return black_frame_buffer_;
 }
 
 }  // namespace rtc