Revert to zero-initializing buffers for FFmpegVideoDecoder

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 232 matching lines @@
   static scoped_refptr<VideoFrame> CreateHoleFrame(const gfx::Size& size);
 #endif  // defined(VIDEO_HOLE)
 
   static size_t NumPlanes(VideoPixelFormat format);
 
   // Returns the required allocation size for a (tightly packed) frame of the
   // given coded size and format.
   static size_t AllocationSize(VideoPixelFormat format,
                                const gfx::Size& coded_size);
 
+  // Returns the actual allocation size for a YUV frame that is created by

[DaleCurtis, 2015/08/03 21:23:25]

Why do we need these two methods again? Can we just make AllocationSize return
the right information?

[emircan, 2015/08/03 21:41:54]

Only VideoFrame::CreateFrame() uses VideoFrame::AllocateYUV() to allocate
buffers and that is not equal to AllocationSize() as some alignments and padding
takes space -exceptional case-.

FFmpegVideoDecoder allocates via VideoFrame::CreateFrame() above. It sets the
pointers to the start of the planes according to the aligned allocation[0].
However, when it calls av_buffer_create, it uses AllocationSize() which is the
packed size [1].

[0]
https://code.google.com/p/chromium/codesearch#chromium/src/media/filters/ffmp...
[1]
https://code.google.com/p/chromium/codesearch#chromium/src/media/filters/ffmp...

I tried changing av_buffer_create() parameter in [2] PatchSet#4 but the bots
didn't like it. I am also not clear why this inconsistency is is there. But
having AlignedAllocationSize() helps me to make sure to zero the whole allocated
buffer. I can use AllocationSize() instead and only zero the packed size as
well. WDYT? 

[2] https://codereview.chromium.org/1227383003

+  // CreateFrame() method.
+  static size_t AlignedAllocationSize(const scoped_refptr<VideoFrame>& frame);
+
   // Returns the plane gfx::Size (in bytes) for a plane of the given coded size
   // and format.
   static gfx::Size PlaneSize(VideoPixelFormat format,
                              size_t plane,
                              const gfx::Size& coded_size);
 
   // Returns horizontal bits per pixel for given |plane| and |format|.
   static int PlaneHorizontalBitsPerPixel(VideoPixelFormat format, size_t plane);
 
   // Returns bits per pixel for given |plane| and |format|.
@@ skipping 213 matching lines @@
   uint32 release_sync_point_;
 
   VideoFrameMetadata metadata_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(VideoFrame);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_VIDEO_FRAME_H_