New method CreateScaledFrame in the VideoFrameFactory interface.

webrtc/common_video/include/video_frame_buffer.h

 /*
  *  Copyright (c) 2015 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 104 matching lines @@
   int StrideU() const override;
   int StrideV() const override;
 
   void* native_handle() const override;
   rtc::scoped_refptr<VideoFrameBuffer> NativeToI420Buffer() override;
 
   // Create a new buffer and copy the pixel data.
   static rtc::scoped_refptr<I420Buffer> Copy(
       const rtc::scoped_refptr<VideoFrameBuffer>& buffer);
 
+  static rtc::scoped_refptr<I420Buffer> Scale(
+      const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
+      int dst_width,
+      int dst_height);
+
+  // Extracts a rectangle of size |crop_width| x |crop_height|, with
+  // lower left corner at |crop_x|, |crop_y|, and returns a new frame

[perkj_webrtc, 2016/05/16 06:48:47]

lower left? -really ? isn't this upper left? 

+  // buffer with the rectangle scaled to size |dst_width| x
+  // |dst_height|. Note that this function doesn't care about aspect
+  // ration; typically, callers select |crop_width| and |crop_height|
+  // so that the aspect ratio is preserved.
+  static rtc::scoped_refptr<I420Buffer> CropAndScale(
+      const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
+      int crop_x,
+      int crop_y,
+      int crop_width,
+      int crop_height,
+      int dst_width,
+      int dst_height);
+
  protected:
   ~I420Buffer() override;
 
  private:
   const int width_;
   const int height_;
   const int stride_y_;
   const int stride_u_;
   const int stride_v_;
   const std::unique_ptr<uint8_t, AlignedFreeDeleter> data_;
@@ skipping 45 matching lines @@
   const uint8_t* DataU() const override;
   const uint8_t* DataV() const override;
   int StrideY() const override;
   int StrideU() const override;
   int StrideV() const override;
 
   void* native_handle() const override;
 
   rtc::scoped_refptr<VideoFrameBuffer> NativeToI420Buffer() override;
 
+  // Helper function to crop |buffer| without making a deep copy. May
+  // only be used for non-native frames.
+  static rtc::scoped_refptr<WrappedI420Buffer> ShallowCrop(
+      const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
+      int crop_x,
+      int crop_y,
+      int cropped_width,
+      int cropped_height);
+
  private:
   friend class rtc::RefCountedObject<WrappedI420Buffer>;
   ~WrappedI420Buffer() override;
 
   const int width_;
   const int height_;
   const uint8_t* const y_plane_;
   const uint8_t* const u_plane_;
   const uint8_t* const v_plane_;
   const int y_stride_;
   const int u_stride_;
   const int v_stride_;
   rtc::Callback0<void> no_longer_used_cb_;
 };
 
 // Helper function to crop |buffer| without making a deep copy. May only be used
 // for non-native frames.
 rtc::scoped_refptr<VideoFrameBuffer> ShallowCenterCrop(
     const rtc::scoped_refptr<VideoFrameBuffer>& buffer,
     int cropped_width,
     int cropped_height);
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_VIDEO_INCLUDE_VIDEO_FRAME_BUFFER_H_