media: Add support for playback of VP8 Alpha video streams

media/filters/skcanvas_video_renderer.cc

Index: media/filters/skcanvas_video_renderer.cc
diff --git a/media/filters/skcanvas_video_renderer.cc b/media/filters/skcanvas_video_renderer.cc
index 53b5b2d57081aa69d500a0ba1043c285f445a316..a68180143e6df09ef50f190414d58648c9ecddd4 100644
--- a/media/filters/skcanvas_video_renderer.cc
+++ b/media/filters/skcanvas_video_renderer.cc
@@ -21,6 +21,17 @@ static bool IsEitherYV12OrYV16OrNative(media::VideoFrame::Format format) {
       format == media::VideoFrame::NATIVE_TEXTURE;
 }
 
+static bool IsEitherYV12OrYV12AOrYV16(media::VideoFrame::Format format) {
+  return IsEitherYV12OrYV16(format) ||
+      format == media::VideoFrame::YV12A;
+}
+
+static bool IsEitherYV12OrYV12AOrYV16OrNative(
+    media::VideoFrame::Format format) {
+  return IsEitherYV12OrYV16OrNative(format) ||
+      format == media::VideoFrame::YV12A;
+}
+
 // CanFastPaint is a helper method to determine the conditions for fast
 // painting. The conditions are:
 // 1. No skew in canvas matrix.
@@ -68,9 +79,12 @@ static void FastPaint(
             video_frame->stride(media::VideoFrame::kVPlane));
 
   const SkBitmap& bitmap = canvas->getDevice()->accessBitmap(true);
-  media::YUVType yuv_type = media::YV16;
+  media::YUVType yuv_type = video_frame->format() == media::VideoFrame::YV12 ||
+                            video_frame->format() == media::VideoFrame::YV12A ?
+                                media::YV12 : media::YV16;
   int y_shift = 0;
-  if (video_frame->format() == media::VideoFrame::YV12) {
+  if (video_frame->format() == media::VideoFrame::YV12 ||
+      video_frame->format() == media::VideoFrame::YV12A) {
     yuv_type = media::YV12;
     y_shift = 1;
   }
@@ -170,9 +184,9 @@ static void FastPaint(
 static void ConvertVideoFrameToBitmap(
     const scoped_refptr<media::VideoFrame>& video_frame,
     SkBitmap* bitmap) {
-  DCHECK(IsEitherYV12OrYV16OrNative(video_frame->format()))
+  DCHECK(IsEitherYV12OrYV12AOrYV16OrNative(video_frame->format()))
       << video_frame->format();
-  if (IsEitherYV12OrYV16(video_frame->format())) {
+  if (IsEitherYV12OrYV12AOrYV16(video_frame->format())) {
     DCHECK_EQ(video_frame->stride(media::VideoFrame::kUPlane),
               video_frame->stride(media::VideoFrame::kVPlane));
   }
@@ -189,10 +203,17 @@ static void ConvertVideoFrameToBitmap(
   }
 
   bitmap->lockPixels();
-  if (IsEitherYV12OrYV16(video_frame->format())) {
-    media::YUVType yuv_type = media::YV16;
+
+  media::YUVType yuv_type;
+  uint8* frame_clip_y;
+  uint8* frame_clip_u;
+  uint8* frame_clip_v;
+  if (IsEitherYV12OrYV12AOrYV16(video_frame->format())) {
+    yuv_type = media::YV16;
+
     int y_shift = 0;
-    if (video_frame->format() == media::VideoFrame::YV12) {
+    if (video_frame->format() == media::VideoFrame::YV12 ||
+        video_frame->format() == media::VideoFrame::YV12A) {
       yuv_type = media::YV12;
       y_shift = 1;
     }
@@ -208,26 +229,48 @@ static void ConvertVideoFrameToBitmap(
     size_t uv_offset = (video_frame->stride(media::VideoFrame::kUPlane) *
                         (video_frame->visible_rect().y() >> y_shift)) +
                        (video_frame->visible_rect().x() >> 1);
-    uint8* frame_clip_y =
-        video_frame->data(media::VideoFrame::kYPlane) + y_offset;
-    uint8* frame_clip_u =
-        video_frame->data(media::VideoFrame::kUPlane) + uv_offset;
-    uint8* frame_clip_v =
-        video_frame->data(media::VideoFrame::kVPlane) + uv_offset;
-
-    media::ConvertYUVToRGB32(frame_clip_y,
-                             frame_clip_u,
-                             frame_clip_v,
-                             static_cast<uint8*>(bitmap->getPixels()),
-                             video_frame->visible_rect().width(),
-                             video_frame->visible_rect().height(),
-                             video_frame->stride(media::VideoFrame::kYPlane),
-                             video_frame->stride(media::VideoFrame::kUPlane),
-                             bitmap->rowBytes(),
-                             yuv_type);
-  } else {
-    DCHECK_EQ(video_frame->format(), media::VideoFrame::NATIVE_TEXTURE);
-    video_frame->ReadPixelsFromNativeTexture(bitmap->getPixels());
+    frame_clip_y = video_frame->data(media::VideoFrame::kYPlane) + y_offset;
+    frame_clip_u = video_frame->data(media::VideoFrame::kUPlane) + uv_offset;
+    frame_clip_v = video_frame->data(media::VideoFrame::kVPlane) + uv_offset;
+  }
+  switch (video_frame->format()) {
+    case media::VideoFrame::YV12:
+    case media::VideoFrame::YV16:
+      media::ConvertYUVToRGB32(frame_clip_y,
+                               frame_clip_u,
+                               frame_clip_v,
+                               static_cast<uint8*>(bitmap->getPixels()),
+                               video_frame->visible_rect().width(),
+                               video_frame->visible_rect().height(),
+                               video_frame->stride(media::VideoFrame::kYPlane),
+                               video_frame->stride(media::VideoFrame::kUPlane),
+                               bitmap->rowBytes(),
+                               yuv_type);
+      break;
+
+    case media::VideoFrame::YV12A:
+      media::ConvertYUVAToARGB(frame_clip_y,
+                               frame_clip_u,
+                               frame_clip_v,
+                               video_frame->data(media::VideoFrame::kAPlane),
+                               static_cast<uint8*>(bitmap->getPixels()),
+                               video_frame->visible_rect().width(),
+                               video_frame->visible_rect().height(),
+                               video_frame->stride(media::VideoFrame::kYPlane),
+                               video_frame->stride(media::VideoFrame::kUPlane),
+                               video_frame->stride(media::VideoFrame::kAPlane),
+                               bitmap->rowBytes(),
+                               media::YV12);

[Tom Finegan, 2013/02/25 22:56:06]

Do we need a comment here about why this is YV12? I know I had to look to
explain it to myself...

+      break;
+
+    case media::VideoFrame::NATIVE_TEXTURE:
+      DCHECK_EQ(video_frame->format(), media::VideoFrame::NATIVE_TEXTURE);
+      video_frame->ReadPixelsFromNativeTexture(bitmap->getPixels());
+      break;
+
+    default:
+      NOTREACHED();
+      break;
   }
   bitmap->notifyPixelsChanged();
   bitmap->unlockPixels();
@@ -255,7 +298,8 @@ void SkCanvasVideoRenderer::Paint(media::VideoFrame* video_frame,
 
   // Paint black rectangle if there isn't a frame available or the
   // frame has an unexpected format.
-  if (!video_frame || !IsEitherYV12OrYV16OrNative(video_frame->format())) {
+  if (!video_frame ||
+      !IsEitherYV12OrYV12AOrYV16OrNative(video_frame->format())) {
     canvas->drawRect(dest, paint);
     return;
   }