Skips the first frame in DxgiDuplicatorController

webrtc/modules/desktop_capture/win/dxgi_output_duplicator.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 13 matching lines @@
 #include "webrtc/modules/desktop_capture/win/dxgi_texture_mapping.h"
 #include "webrtc/modules/desktop_capture/win/dxgi_texture_staging.h"
 
 namespace webrtc {
 
 using Microsoft::WRL::ComPtr;
 
 namespace {
 
 // Timeout for AcquireNextFrame() call.
-const int kAcquireTimeoutMs = 10;
+// DxgiDuplicatorController leverages external components to do the capture
+// scheduling. So here DxgiOutputDuplicator does not need to actively wait for a
+// new frame. 1 millisecond is the minimium value AcquireNextFrame() accepts.
+const int kAcquireTimeoutMs = 1;
 
 DesktopRect RECTToDesktopRect(const RECT& rect) {
   return DesktopRect::MakeLTRB(rect.left, rect.top, rect.right, rect.bottom);
 }
 
 Rotation DxgiRotationToRotation(DXGI_MODE_ROTATION rotation) {
   switch (rotation) {
     case DXGI_MODE_ROTATION_IDENTITY:
     case DXGI_MODE_ROTATION_UNSPECIFIED:
       return Rotation::CLOCK_WISE_0;
@@ skipping 152 matching lines @@
     } else {
       for (DesktopRegion::Iterator it(updated_region); !it.IsAtEnd();
            it.Advance()) {
         target->CopyPixelsFrom(
             source, ReverseTranslate(it.rect(), offset).top_left(), it.rect());
       }
     }
     last_frame_ = target->Share();
     last_frame_offset_ = offset;
     target->mutable_updated_region()->AddRegion(updated_region);
+    num_frames_captured_++;
     return texture_->Release() && ReleaseFrame();
   }
 
   if (last_frame_) {
     // No change since last frame or AcquireNextFrame() timed out, we will
     // export last frame to the target.
     for (DesktopRegion::Iterator it(updated_region); !it.IsAtEnd();
          it.Advance()) {
       target->CopyPixelsFrom(*last_frame_, it.rect().top_left(), it.rect());
     }
@@ skipping 114 matching lines @@
 
 void DxgiOutputDuplicator::SpreadContextChange(const Context* const source) {
   for (Context* dest : contexts_) {
     RTC_DCHECK(dest);
     if (dest != source) {
       dest->updated_region.AddRegion(source->updated_region);
     }
   }
 }
 
+int64_t DxgiOutputDuplicator::num_frames_captured() const {
+#if !defined(NDEBUG)
+  RTC_DCHECK_EQ(!!last_frame_, num_frames_captured_ > 0);
+#endif
+  return num_frames_captured_;
+}
+
 }  // namespace webrtc