Speed up vertical filtering using v = a+(b-a)*x formula...

media/base/yuv_convert.h

 // Copyright (c) 2010 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_YUV_CONVERT_H_
 #define MEDIA_BASE_YUV_CONVERT_H_
 
 #include "base/basictypes.h"
 
 namespace media {
@@ skipping 13 matching lines @@
   ROTATE_180,         // Rotate upside down.
   ROTATE_270,         // Rotate counter clockwise.
   MIRROR_ROTATE_0,    // Mirror horizontally.
   MIRROR_ROTATE_90,   // Mirror then Rotate clockwise.
   MIRROR_ROTATE_180,  // Mirror vertically.
   MIRROR_ROTATE_270,  // Transpose.
 };
 
 // Filter affects how scaling looks.
 enum ScaleFilter {
-  FILTER_NONE,        // No filter (point sampled).
-  FILTER_BILINEAR,    // Bilinear filter.
+  FILTER_NONE = 0,        // No filter (point sampled).
+  FILTER_BILINEAR_H = 1,  // Bilinear horizontal filter.
+  FILTER_BILINEAR_V = 2,  // Bilinear vertical filter.
+  FILTER_BILINEAR = 3,    // Bilinear filter.
 };
 
 // Convert a frame of YUV to 32 bit ARGB.
 // Pass in YV16/YV12 depending on source format
 void ConvertYUVToRGB32(const uint8* yplane,
                        const uint8* uplane,
                        const uint8* vplane,
                        uint8* rgbframe,
                        int width,
                        int height,
@@ skipping 15 matching lines @@
                      int ystride,
                      int uvstride,
                      int rgbstride,
                      YUVType yuv_type,
                      Rotate view_rotate,
                      ScaleFilter filter);
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_YUV_CONVERT_H_