Send bytes_used of v4l2 captured frame when video capture

media/video/capture/linux/v4l2_capture_delegate.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
 #define MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_
 
 #if defined(OS_OPENBSD)
 #include <sys/videoio.h>
 #else
@@ skipping 48 matching lines @@
     BufferTracker();
     // Abstract method to mmap() given |fd| according to |buffer|, planarity
     // specific.
     virtual bool Init(int fd, const v4l2_buffer& buffer) = 0;
 
     uint8_t* const GetPlaneStart(size_t plane) const {
       DCHECK_LT(plane, planes_.size());
       return planes_[plane].start;
     }
 
+    size_t GetPlanePayload(size_t plane) const {
+      DCHECK_LT(plane, planes_.size());
+      return planes_[plane].payload;
+    }
+
+    void SetPlanePayload(size_t plane, size_t payload) {
+      DCHECK_LT(plane, planes_.size());
+      planes_[plane].payload = payload;
+    }
+
    protected:
     friend class base::RefCounted<BufferTracker>;
     virtual ~BufferTracker();
     // Adds a given mmap()ed plane to |planes_|.
     void AddMmapedPlane(uint8_t* const start, size_t length);
 
    private:
     struct Plane {
       uint8_t* start;
       size_t length;
+      size_t payload;
     };
     std::vector<Plane> planes_;
   };
 
   V4L2CaptureDelegate(
       const VideoCaptureDevice::Name& device_name,
       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
       int power_line_frequency);
   virtual ~V4L2CaptureDelegate();
 
   // Creates the necessary, planarity-specific, internal tracking schemes,
   virtual scoped_refptr<BufferTracker> CreateBufferTracker() const = 0;
 
   // Fill in |format| with the given parameters, in a planarity dependent way.
   virtual bool FillV4L2Format(v4l2_format* format,
                               uint32_t width,
                               uint32_t height,
                               uint32_t pixelformat_fourcc) const = 0;
 
   // Finish filling |buffer| struct with planarity-dependent data.
   virtual void FinishFillingV4L2Buffer(v4l2_buffer* buffer) const = 0;
 
+  // Fetch the number of bytes occupied by data in |buffer| and set to
+  // |buffer_tracker|.
+  virtual void FetchBytesUsed(

[kcwu, 2015/05/20 12:14:53]

any suggestion for the name? I feel it not good.

+      const scoped_refptr<BufferTracker>& buffer_tracker,
+      const v4l2_buffer* buffer) const = 0;
+
   // Sends the captured |buffer| to the |client_|, synchronously.
   virtual void SendBuffer(
       const scoped_refptr<BufferTracker>& buffer_tracker,
       const v4l2_format& format) const = 0;
 
   // A few accessors for SendBuffer()'s to access private member variables.
   VideoCaptureFormat capture_format() const { return capture_format_; }
   VideoCaptureDevice::Client* client() const { return client_.get(); }
   int rotation() const { return rotation_; }
 
@@ skipping 30 matching lines @@
 
   // Clockwise rotation in degrees. This value should be 0, 90, 180, or 270.
   int rotation_;
 
   DISALLOW_COPY_AND_ASSIGN(V4L2CaptureDelegate);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_VIDEO_CAPTURE_LINUX_V4L2_VIDEO_CAPTURE_DELEGATE_H_