media: Add support for playback of VP8 Alpha video streams

media/base/yuv_convert.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.
 
 // This webpage shows layout of YV12 and other YUV formats
 // http://www.fourcc.org/yuv.php
 // The actual conversion is best described here
 // http://en.wikipedia.org/wiki/YUV
 // An article on optimizing YUV conversion using tables instead of multiplies
 // http://lestourtereaux.free.fr/papers/data/yuvrgb.pdf
@@ skipping 585 matching lines @@
       convert_proc = &ConvertYUVToRGB32_MMX;
     else
       convert_proc = &ConvertYUVToRGB32_C;
   }
 
   convert_proc(yplane, uplane, vplane, rgbframe,
                width, height, ystride, uvstride, rgbstride, yuv_type);
 #endif
 }
 
+void ConvertYUVAToARGB(const uint8* yplane,
+                       const uint8* uplane,
+                       const uint8* vplane,
+                       const uint8* aplane,
+                       uint8* rgbframe,
+                       int width,
+                       int height,
+                       int ystride,
+                       int uvstride,
+                       int astride,
+                       int rgbstride,
+                       YUVType yuv_type) {
+#if defined(ARCH_CPU_ARM_FAMILY) || defined(ARCH_CPU_MIPS_FAMILY)
+  ConvertYUVAToARGB_C(yplane, uplane, vplane, aplane, rgbframe,
+                      width, height, ystride, uvstride, astride, rgbstride,
+                      yuv_type);
+#else
+  static ConvertYUVAToARGBProc convert_proc = NULL;
+  if (!convert_proc) {
+    base::CPU cpu;
+    if (cpu.has_mmx())
+      convert_proc = &ConvertYUVAToARGB_MMX;
+    else
+      convert_proc = &ConvertYUVAToARGB_C;
+  }
+  convert_proc(yplane, uplane, vplane, aplane, rgbframe,
+               width, height, ystride, uvstride, astride, rgbstride, yuv_type);
+#endif
+}
+
 }  // namespace media