FFmpeg video decoder glue code...

media/base/buffers.h

 // Copyright (c) 2008-2009 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.
 
 // Defines various types of timestamped media buffers used for transporting
 // data between filters.  Every buffer contains a timestamp in microseconds
 // describing the relative position of the buffer within the media stream, and
 // the duration in microseconds for the length of time the buffer will be
 // rendered.
 //
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   // Width and height of surface.
   size_t width;
   size_t height;
 
   // Number of planes, typically 1 for packed RGB formats and 3 for planar
   // YUV formats.
   size_t planes;
 
   // Array of strides for each plane, typically greater or equal to the width
-  // of the surface divided by the horizontal sampling period.
-  size_t strides[kMaxPlanes];
+  // of the surface divided by the horizontal sampling period.  Note that
+  // strides can be negative.
+  int32 strides[kMaxPlanes];
 
   // Array of data pointers to each plane.
   uint8* data[kMaxPlanes];
 };
 
 
 class VideoFrame : public StreamSample {
  public:
   // Locks the underlying surface and fills out the given VideoSurface and
   // returns true if successful, false otherwise.  Any additional calls to Lock
   // will fail.
   virtual bool Lock(VideoSurface* surface) = 0;
 
   // Unlocks the underlying surface, the VideoSurface acquired from Lock is no
   // longer guaranteed to be valid.
   virtual void Unlock() = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_BUFFERS_H_