Update sink wants with ranges for both pixel count and frame rate.

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 62 matching lines @@
   }
 }
 
 void VideoBroadcaster::UpdateWants() {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
 
   VideoSinkWants wants;
   wants.rotation_applied = false;
   for (auto& sink : sink_pairs()) {
     // wants.rotation_applied == ANY(sink.wants.rotation_applied)
-    if (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;
-    }
-    // Select the minimum requested target_pixel_count, if any, of all sinks so
-    // that we don't over utilize the resources for any one.
-    // TODO(sprang): Consider using the median instead, since the limit can be
-    // expressed by max_pixel_count.
-    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 (sink.wants.pixel_count) {
+      if (!wants.pixel_count) {
+        wants.pixel_count = sink.wants.pixel_count;
+      } else {
+        // Merge the constraints if there are more than one wants. Lowest max
+        // will set the max cap and the highest min will set the min cap, as
+        // these are pretty hard bounds. For now chose the min of the targets as
+        // well, erring of the side of caution so that we don't overutilize some
+        // resource.
+        // TODO(sprang): Consider using median of targets?
+        wants.pixel_count->max = std::min<uint32_t>(
+            wants.pixel_count->max, sink.wants.pixel_count->max);
+        wants.pixel_count->target = std::min<uint32_t>(
+            wants.pixel_count->target, sink.wants.pixel_count->target);
+        wants.pixel_count->min = std::max<uint32_t>(
+            wants.pixel_count->min, sink.wants.pixel_count->min);
+      }
     }
   }
 
-  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;
+  if (wants.pixel_count) {
+    // Make sure there is no contradiction in the merged wants.
+    wants.pixel_count->min =
+        std::min<uint32_t>(wants.pixel_count->min, wants.pixel_count->max);
+    wants.pixel_count->target =
+        std::min<uint32_t>(wants.pixel_count->target, wants.pixel_count->max);
+    wants.pixel_count->target =
+        std::max<uint32_t>(wants.pixel_count->target, wants.pixel_count->min);
   }
   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