media: VideoFrame: add offset for shared memory buffers

media/base/video_frame.h

 // Copyright (c) 2012 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_BASE_VIDEO_FRAME_H_
 #define MEDIA_BASE_VIDEO_FRAME_H_
 
 #include <vector>
 
 #include "base/callback.h"
@@ skipping 120 matching lines @@
   // frame is destroyed, |no_longer_needed_cb.Run()| will be called.
   // Returns NULL on failure.
   static scoped_refptr<VideoFrame> WrapExternalPackedMemory(
       Format format,
       const gfx::Size& coded_size,
       const gfx::Rect& visible_rect,
       const gfx::Size& natural_size,
       uint8* data,
       size_t data_size,
       base::SharedMemoryHandle handle,
+      size_t data_offset,

[bbudge, 2015/01/28 18:47:07]

Naming this 'data_offset' makes it look odd that it isn't grouped with data and
data_size.
How about naming this to match shared_memory_offset below?

[llandwerlin-old, 2015/01/30 08:03:41]

Done.

       base::TimeDelta timestamp,
       const base::Closure& no_longer_needed_cb);
 
 #if defined(OS_POSIX)
   // Wraps provided dmabufs
   // (https://www.kernel.org/doc/Documentation/dma-buf-sharing.txt) with a
   // VideoFrame. The dmabuf fds are dup()ed on creation, so that the VideoFrame
   // retains a reference to them, and are automatically close()d on destruction,
   // dropping the reference. The caller may safely close() its reference after
   // calling WrapExternalDmabufs().
@@ skipping 141 matching lines @@
   uint8* visible_data(size_t plane);
 
   // Returns the mailbox holder of the native texture wrapped by this frame.
   // Only valid to call if this is a NATIVE_TEXTURE frame. Before using the
   // mailbox, the caller must wait for the included sync point.
   const gpu::MailboxHolder* mailbox_holder() const;
 
   // Returns the shared-memory handle, if present
   base::SharedMemoryHandle shared_memory_handle() const;
 
+  // Return the offset with the shared-memory handle.

[bbudge, 2015/01/28 18:47:07]

Nit: wording. How about..
// Return the offset into the shared memory where the frame data begins.

[llandwerlin-old, 2015/01/30 08:03:40]

Done.

+  size_t shared_memory_offset() const;
+
 #if defined(OS_POSIX)
   // Returns backing dmabuf file descriptor for given |plane|, if present.
   int dmabuf_fd(size_t plane) const;
 #endif
 
 #if defined(OS_MACOSX)
   // Returns the backing CVPixelBuffer, if present.
   CVPixelBufferRef cv_pixel_buffer() const;
 #endif
 
@@ skipping 71 matching lines @@
   uint8* data_[kMaxPlanes];
 
   // Native texture mailbox, if this is a NATIVE_TEXTURE frame.
   const scoped_ptr<gpu::MailboxHolder> mailbox_holder_;
   ReleaseMailboxCB mailbox_holder_release_cb_;
   ReadPixelsCB read_pixels_cb_;
 
   // Shared memory handle, if this frame was allocated from shared memory.
   base::SharedMemoryHandle shared_memory_handle_;
 
+  // Offset in shared memory buffer.
+  size_t shared_memory_offset_;
+
 #if defined(OS_POSIX)
   // Dmabufs for each plane, if this frame is wrapping memory
   // acquired via dmabuf.
   base::ScopedFD dmabuf_fds_[kMaxPlanes];
 #endif
 
 #if defined(OS_MACOSX)
   // CVPixelBuffer, if this frame is wrapping one.
   base::ScopedCFTypeRef<CVPixelBufferRef> cv_pixel_buffer_;
 #endif
 
   base::Closure no_longer_needed_cb_;
 
   base::TimeDelta timestamp_;
 
   base::Lock release_sync_point_lock_;
   uint32 release_sync_point_;
 
   const bool end_of_stream_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(VideoFrame);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_FRAME_H_