media: Add support for playback of VP8 Alpha video streams

media/base/simd/convert_yuv_to_rgb_c.cc

Index: media/base/simd/convert_yuv_to_rgb_c.cc
diff --git a/media/base/simd/convert_yuv_to_rgb_c.cc b/media/base/simd/convert_yuv_to_rgb_c.cc
index 2849cac28d658ceb7690ad0f8a1a02d0ac126ca9..e09ed137405638880051f1cb3ae4cfd5f32c57ed 100644
--- a/media/base/simd/convert_yuv_to_rgb_c.cc
+++ b/media/base/simd/convert_yuv_to_rgb_c.cc
@@ -39,6 +39,34 @@ static inline void ConvertYUVToRGB32_C(uint8 y,
                                         (packuswb(a) << 24);
 }
 
+static inline void ConvertYUVAToARGB_C(uint8 y,
+                                       uint8 u,
+                                       uint8 v,
+                                       uint8 a,
+                                       uint8* rgb_buf) {
+  int b = kCoefficientsRgbY[256+u][0];
+  int g = kCoefficientsRgbY[256+u][1];
+  int r = kCoefficientsRgbY[256+u][2];
+
+  b = paddsw(b, kCoefficientsRgbY[512+v][0]);
+  g = paddsw(g, kCoefficientsRgbY[512+v][1]);
+  r = paddsw(r, kCoefficientsRgbY[512+v][2]);
+
+  b = paddsw(b, kCoefficientsRgbY[y][0]);
+  g = paddsw(g, kCoefficientsRgbY[y][1]);
+  r = paddsw(r, kCoefficientsRgbY[y][2]);
+
+  b >>= 6;
+  g >>= 6;
+  r >>= 6;
+
+  b = packuswb(b) * a >> 8;
+  g = packuswb(g) * a >> 8;
+  r = packuswb(r) * a >> 8;
+
+  *reinterpret_cast<uint32*>(rgb_buf) = b | (g << 8) | (r << 16) | (a << 24);
+}
+
 extern "C" {
 
 void ConvertYUVToRGB32Row_C(const uint8* y_buf,
@@ -59,6 +87,27 @@ void ConvertYUVToRGB32Row_C(const uint8* y_buf,
   }
 }
 
+void ConvertYUVAToARGBRow_C(const uint8* y_buf,
+                            const uint8* u_buf,
+                            const uint8* v_buf,
+                            const uint8* a_buf,
+                            uint8* rgba_buf,
+                            ptrdiff_t width) {
+  for (int x = 0; x < width; x += 2) {
+    uint8 u = u_buf[x >> 1];
+    uint8 v = v_buf[x >> 1];
+    uint8 y0 = y_buf[x];
+    uint8 a0 = a_buf[x];
+    ConvertYUVAToARGB_C(y0, u, v, a0, rgba_buf);
+    if ((x + 1) < width) {
+      uint8 y1 = y_buf[x + 1];
+      uint8 a1 = a_buf[x + 1];
+      ConvertYUVAToARGB_C(y1, u, v, a1, rgba_buf + 4);
+    }
+    rgba_buf += 8;  // Advance 2 pixels.
+  }
+}
+
 // 16.16 fixed point is used.  A shift by 16 isolates the integer.
 // A shift by 17 is used to further subsample the chrominence channels.
 // & 0xffff isolates the fixed point fraction.  >> 2 to get the upper 2 bits,
@@ -161,4 +210,33 @@ void ConvertYUVToRGB32_C(const uint8* yplane,
   }
 }
 
+void ConvertYUVAToARGB_C(const uint8* yplane,
+                         const uint8* uplane,
+                         const uint8* vplane,
+                         const uint8* aplane,
+                         uint8* rgbaframe,
+                         int width,
+                         int height,
+                         int ystride,
+                         int uvstride,
+                         int astride,
+                         int rgbastride,
+                         YUVType yuv_type) {
+  unsigned int y_shift = yuv_type;
+  for (int y = 0; y < height; y++) {
+    uint8* rgba_row = rgbaframe + y * rgbastride;
+    const uint8* y_ptr = yplane + y * ystride;
+    const uint8* u_ptr = uplane + (y >> y_shift) * uvstride;
+    const uint8* v_ptr = vplane + (y >> y_shift) * uvstride;
+    const uint8* a_ptr = aplane + y * astride;
+
+    ConvertYUVAToARGBRow_C(y_ptr,
+                           u_ptr,
+                           v_ptr,
+                           a_ptr,
+                           rgba_row,
+                           width);
+  }
+}
+
 }  // namespace media