Reintroduce kFramePadBytes in frame allocation.

media/base/video_frame.cc

 // 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.
 
 #include "media/base/video_frame.h"
 
 #include "base/logging.h"
 #include "base/string_piece.h"
 #include "media/base/limits.h"
 #include "media/base/video_util.h"
@@ skipping 81 matching lines @@
   return frame;
 }
 
 static inline size_t RoundUp(size_t value, size_t alignment) {
   // Check that |alignment| is a power of 2.
   DCHECK((alignment + (alignment - 1)) == (alignment | (alignment - 1)));
   return ((value + (alignment - 1)) & ~(alignment-1));
 }
 
 static const int kFrameSizeAlignment = 16;
+// Allows faster SIMD YUV convert. Also, FFmpeg overreads/-writes occasionally.
+static const int kFramePadBytes = 15;
 
 void VideoFrame::AllocateRGB(size_t bytes_per_pixel) {
   // Round up to align at least at a 16-byte boundary for each row.
   // This is sufficient for MMX and SSE2 reads (movq/movdqa).
   size_t bytes_per_row = RoundUp(width_, kFrameSizeAlignment) * bytes_per_pixel;
   size_t aligned_height = RoundUp(height_, kFrameSizeAlignment);
   strides_[VideoFrame::kRGBPlane] = bytes_per_row;
 #if !defined(OS_ANDROID)
   // TODO(dalecurtis): use DataAligned or so, so this #ifdef hackery
   // doesn't need to be repeated in every single user of aligned data.
   data_[VideoFrame::kRGBPlane] = reinterpret_cast<uint8*>(
-      av_malloc(bytes_per_row * aligned_height));
+      av_malloc(bytes_per_row * aligned_height + kFramePadBytes));

[DaleCurtis, 2012/07/09 23:25:51]

FF_INPUT_BUFFER_PADDING_SIZE instead ?

 #else
   data_[VideoFrame::kRGBPlane] = new uint8_t[bytes_per_row * aligned_height];
 #endif
   DCHECK(!(reinterpret_cast<intptr_t>(data_[VideoFrame::kRGBPlane]) & 7));
   COMPILE_ASSERT(0 == VideoFrame::kRGBPlane, RGB_data_must_be_index_0);
 }
 
 void VideoFrame::AllocateYUV() {
   DCHECK(format_ == VideoFrame::YV12 || format_ == VideoFrame::YV16);
   // Align Y rows at least at 16 byte boundaries.  The stride for both
@@ skipping 11 matching lines @@
                              kFrameSizeAlignment);
   size_t y_height = RoundUp(height_, kFrameSizeAlignment);
   size_t uv_height = format_ == VideoFrame::YV12 ? y_height / 2 : y_height;
   size_t y_bytes = y_height * y_stride;
   size_t uv_bytes = uv_height * uv_stride;
 
 #if !defined(OS_ANDROID)
   // TODO(dalecurtis): use DataAligned or so, so this #ifdef hackery
   // doesn't need to be repeated in every single user of aligned data.
   uint8* data = reinterpret_cast<uint8*>(
-      av_malloc(y_bytes + (uv_bytes * 2)));
+      av_malloc(y_bytes + (uv_bytes * 2) + kFramePadBytes));
 #else
   uint8* data = new uint8_t[y_bytes + (uv_bytes * 2)];
 #endif
   COMPILE_ASSERT(0 == VideoFrame::kYPlane, y_plane_data_must_be_index_0);
   data_[VideoFrame::kYPlane] = data;
   data_[VideoFrame::kUPlane] = data + y_bytes;
   data_[VideoFrame::kVPlane] = data + y_bytes + uv_bytes;
   strides_[VideoFrame::kYPlane] = y_stride;
   strides_[VideoFrame::kUPlane] = uv_stride;
   strides_[VideoFrame::kVPlane] = uv_stride;
@@ skipping 129 matching lines @@
       break;
     for(int row = 0; row < rows(plane); row++) {
       base::MD5Update(context, base::StringPiece(
           reinterpret_cast<char*>(data(plane) + stride(plane) * row),
           row_bytes(plane)));
     }
   }
 }
 
 }  // namespace media