Move VideoFrame and related declarations to webrtc/api/video.

webrtc/api/video/i420_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.
+ */
+
+#ifndef WEBRTC_API_VIDEO_I420_BUFFER_H_
+#define WEBRTC_API_VIDEO_I420_BUFFER_H_
+
+#include <memory>
+
+#include "webrtc/api/video/video_rotation.h"
+#include "webrtc/api/video/video_frame_buffer.h"
+#include "webrtc/system_wrappers/include/aligned_malloc.h"
+
+namespace webrtc {
+
+// Plain I420 buffer in standard memory.
+class I420Buffer : public VideoFrameBuffer {
+ public:
+  static rtc::scoped_refptr<I420Buffer> Create(int width, int height);
+  static rtc::scoped_refptr<I420Buffer> Create(int width,
+                                               int height,
+                                               int stride_y,
+                                               int stride_u,
+                                               int stride_v);
+
+  // Create a new buffer and copy the pixel data.
+  static rtc::scoped_refptr<I420Buffer> Copy(const VideoFrameBuffer& buffer);
+
+  static rtc::scoped_refptr<I420Buffer> Copy(
+      int width, int height,
+      const uint8_t* data_y, int stride_y,
+      const uint8_t* data_u, int stride_u,
+      const uint8_t* data_v, int stride_v);
+
+  // Returns a rotated copy of |src|.
+  static rtc::scoped_refptr<I420Buffer> Rotate(const VideoFrameBuffer& src,

[the sun, 2016/12/05 22:36:29]

IIUC most of these utility functions don't even need to be static members, they
can be implemented outside of the class because all fields they access are
exposed through member functions.

 suggest you either remove from the public API, or, if we really want to support
them, put in a separate namespace (e.g. i420buffer_utils). That namespace should
be in a separate build target, because then only users of those particular
functions need to depend on libyuv - a 'casual' user of I420Buffer won't need
it, and the class remains a 'stupid' POD-like buffer.

[nisse-webrtc, 2016/12/06 12:02:15]

I found webrtc::I420Buffer::Rotate to be a reasonable name. Precisely what do
you suggest instead? webrtc::i420buffer_utils::Rotate looks a bit clumsy to me.
Will it make any practical difference? I would expect almost any executable
which depends on video_frame_api to include at least one object (at the creation
or consumption end of the pipeline) which uses either some of these helper
functions, or uses libyuv directly. 

[the sun, 2016/12/07 15:43:51]

If it makes no practical difference, then leave it.

+                                               VideoRotation rotation);
+
+  // Sets all three planes to all zeros. Used to work around for
+  // quirks in memory checkers
+  // (https://bugs.chromium.org/p/libyuv/issues/detail?id=377) and
+  // ffmpeg (http://crbug.com/390941).
+  // TODO(nisse): Deprecated. Should be deleted if/when those issues
+  // are resolved in a better way.
+  void InitializeData();
+
+  // Sets the frame buffer to all black.
+  // TODO(nisse): Make this a static method instead?
+  void SetToBlack();
+
+  int width() const override;
+  int height() const override;
+  const uint8_t* DataY() const override;
+  const uint8_t* DataU() const override;
+  const uint8_t* DataV() const override;
+
+  uint8_t* MutableDataY();

[the sun, 2016/12/05 22:36:29]

Put overrides from base class together in one section, and these in another.

[nisse-webrtc, 2016/12/06 12:02:15]

Ok, will reorder.

[nisse-webrtc, 2016/12/13 15:08:02]

Done.

+  uint8_t* MutableDataU();
+  uint8_t* MutableDataV();
+  int StrideY() const override;
+  int StrideU() const override;
+  int StrideV() const override;
+
+  void* native_handle() const override;
+  rtc::scoped_refptr<VideoFrameBuffer> NativeToI420Buffer() override;
+
+  // Scale the cropped area of |src| to the size of |this| buffer, and
+  // write the result into |this|.
+  void CropAndScaleFrom(const VideoFrameBuffer& src,
+                        int offset_x,
+                        int offset_y,
+                        int crop_width,
+                        int crop_height);
+
+  // The common case of a center crop, when needed to adjust the
+  // aspect ratio without distorting the image.
+  void CropAndScaleFrom(const VideoFrameBuffer& src);
+
+  // Scale all of |src| to the size of |this| buffer, with no cropping.
+  void ScaleFrom(const VideoFrameBuffer& src);
+
+  // TODO(nisse): Deprecated, delete once downstream applications are updated.
+  // Returns a rotated versions of |src|. Native buffers are not
+  // supported. The reason this function doesn't return an I420Buffer,
+  // is that it returns |src| unchanged in case |rotation| is zero.
+  static rtc::scoped_refptr<VideoFrameBuffer> Rotate(
+      rtc::scoped_refptr<VideoFrameBuffer> src,
+      VideoRotation rotation);
+
+ protected:
+  I420Buffer(int width, int height);
+  I420Buffer(int width, int height, int stride_y, int stride_u, int stride_v);
+
+  ~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_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_VIDEO_I420_BUFFER_H_