RESOURCE_UTILIZATION in VideoFrameMetadata, a consumer feedback signal.

content/browser/renderer_host/media/video_capture_controller.cc

Index: content/browser/renderer_host/media/video_capture_controller.cc
diff --git a/content/browser/renderer_host/media/video_capture_controller.cc b/content/browser/renderer_host/media/video_capture_controller.cc
index fd098e7f96f081441aaabb8111c6675ad13448ff..a06c30d8f9a6d21850c46b13092f41db4a576593 100644
--- a/content/browser/renderer_host/media/video_capture_controller.cc
+++ b/content/browser/renderer_host/media/video_capture_controller.cc
@@ -28,6 +28,7 @@
 
 using media::VideoCaptureFormat;
 using media::VideoFrame;
+using media::VideoFrameMetadata;
 
 namespace content {
 
@@ -234,7 +235,8 @@ void VideoCaptureController::ReturnBuffer(
     VideoCaptureControllerID id,
     VideoCaptureControllerEventHandler* event_handler,
     int buffer_id,
-    uint32 sync_point) {
+    uint32 sync_point,
+    double consumer_resource_utilization) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   ControllerClient* client = FindClient(id, event_handler, controller_clients_);
@@ -247,7 +249,25 @@ void VideoCaptureController::ReturnBuffer(
     NOTREACHED();
     return;
   }
+
+  // Set the RESOURCE_UTILIZATION to the maximum of those provided by each

[hubbe, 2015/06/04 22:08:53]

This comment is confusing me a bit as it seems to suggest that there are
multiple consumers of the frame...

There is definitely two different sources of resource_utilization here though,
perhaps the comment can clarify where they come from?

[miu, 2015/06/06 00:29:22]

There are!  :)  Throughout the VideoCaptureController, this is a known part of
the design.

Clarified the comment, in that multiple calls of the method are coming from
different consumers that all reference the same VideoFrame.

+  // consumer.  A producer of the VideoFrame may check this value to make
+  // quality versus performance trade-off decisions.
   scoped_refptr<VideoFrame> frame = iter->second;
+  if (std::isfinite(consumer_resource_utilization) &&
+      consumer_resource_utilization >= 0.0) {
+    double resource_utilization = -1.0;
+    if (frame->metadata()->GetDouble(VideoFrameMetadata::RESOURCE_UTILIZATION,
+                                     &resource_utilization)) {
+      frame->metadata()->SetDouble(VideoFrameMetadata::RESOURCE_UTILIZATION,
+                                   std::max(consumer_resource_utilization,
+                                            resource_utilization));
+    } else {
+      frame->metadata()->SetDouble(VideoFrameMetadata::RESOURCE_UTILIZATION,
+                                   consumer_resource_utilization);
+    }
+  }
+
   client->active_buffers.erase(iter);
   buffer_pool_->RelinquishConsumerHold(buffer_id, 1);