Refactor VideoDenoiser to use a buffer pool, replacing explicit double buffering.

webrtc/modules/video_processing/frame_preprocessor.cc

 /*
  *  Copyright (c) 2012 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.
  */
 
 #include "webrtc/modules/video_processing/frame_preprocessor.h"
 
 #include "webrtc/modules/video_processing/video_denoiser.h"
 
 namespace webrtc {
 
 VPMFramePreprocessor::VPMFramePreprocessor()
     : resampled_frame_(), frame_cnt_(0) {
   spatial_resampler_ = new VPMSimpleSpatialResampler();
   vd_ = new VPMVideoDecimator();
   EnableDenoising(false);
-  denoised_frame_toggle_ = 0;
 }
 
 VPMFramePreprocessor::~VPMFramePreprocessor() {
   Reset();
   delete vd_;
   delete spatial_resampler_;
 }
 
 void VPMFramePreprocessor::Reset() {
   vd_->Reset();
@@ skipping 56 matching lines @@
     return nullptr;
   }
 
   vd_->UpdateIncomingframe_rate();
   if (vd_->DropFrame()) {
     return nullptr;
   }
 
   const VideoFrame* current_frame = &frame;
   if (denoiser_) {
-    rtc::scoped_refptr<I420Buffer>* denoised_buffer = &denoised_buffer_[0];
-    rtc::scoped_refptr<I420Buffer>* denoised_buffer_prev = &denoised_buffer_[1];
-    // Swap the buffer to save one memcpy in DenoiseFrame.
-    if (denoised_frame_toggle_) {
-      denoised_buffer = &denoised_buffer_[1];
-      denoised_buffer_prev = &denoised_buffer_[0];
-    }
-    // Invert the flag.
-    denoised_frame_toggle_ ^= 1;
-    denoiser_->DenoiseFrame(current_frame->video_frame_buffer(),
-                            denoised_buffer,
-                            denoised_buffer_prev, true);
-    denoised_frame_ = VideoFrame(*denoised_buffer,
-                                 current_frame->timestamp(),
-                                 current_frame->render_time_ms(),
-                                 current_frame->rotation());
+    denoised_frame_ = VideoFrame(
+        denoiser_->DenoiseFrame(current_frame->video_frame_buffer(), true),
+        current_frame->timestamp(), current_frame->render_time_ms(),
+        current_frame->rotation());
     current_frame = &denoised_frame_;
   }
 
   if (spatial_resampler_->ApplyResample(current_frame->width(),
                                         current_frame->height())) {
     if (spatial_resampler_->ResampleFrame(*current_frame, &resampled_frame_) !=
         VPM_OK) {
       return nullptr;
     }
     current_frame = &resampled_frame_;
   }
 
   ++frame_cnt_;
   return current_frame;
 }
 
 }  // namespace webrtc