media: Add support for playback of VP8 Alpha video streams

media/base/video_frame.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.
 
 #include "media/base/video_frame.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 13 matching lines @@
     const gfx::Size& natural_size,
     base::TimeDelta timestamp) {
   DCHECK(IsValidConfig(format, coded_size, visible_rect, natural_size));
   scoped_refptr<VideoFrame> frame(new VideoFrame(
       format, coded_size, visible_rect, natural_size, timestamp));
   switch (format) {
     case VideoFrame::RGB32:
       frame->AllocateRGB(4u);
       break;
     case VideoFrame::YV12:
+    case VideoFrame::YV12A:
     case VideoFrame::YV16:
       frame->AllocateYUV();
       break;
     default:
       LOG(FATAL) << "Unsupported frame format: " << format;
   }
   return frame;
 }
 
 // static
@@ skipping 112 matching lines @@
   strides_[VideoFrame::kRGBPlane] = bytes_per_row;
   data_[VideoFrame::kRGBPlane] = reinterpret_cast<uint8*>(
       base::AlignedAlloc(bytes_per_row * aligned_height + kFrameSizePadding,
                          kFrameAddressAlignment));
   no_longer_needed_cb_ = base::Bind(&ReleaseData, data_[VideoFrame::kRGBPlane]);
   DCHECK(!(reinterpret_cast<intptr_t>(data_[VideoFrame::kRGBPlane]) & 7));
   COMPILE_ASSERT(0 == VideoFrame::kRGBPlane, RGB_data_must_be_index_0);
 }
 
 void VideoFrame::AllocateYUV() {
-  DCHECK(format_ == VideoFrame::YV12 || format_ == VideoFrame::YV16);
+  DCHECK(format_ == VideoFrame::YV12 || format_ == VideoFrame::YV16 ||
+         format_ == VideoFrame::YV12A);
   // Align Y rows at least at 16 byte boundaries.  The stride for both
   // YV12 and YV16 is 1/2 of the stride of Y.  For YV12, every row of bytes for
   // U and V applies to two rows of Y (one byte of UV for 4 bytes of Y), so in
   // the case of YV12 the strides are identical for the same width surface, but
   // the number of bytes allocated for YV12 is 1/2 the amount for U & V as
   // YV16. We also round the height of the surface allocated to be an even
   // number to avoid any potential of faulting by code that attempts to access
   // the Y values of the final row, but assumes that the last row of U & V
-  // applies to a full two rows of Y.
+  // applies to a full two rows of Y. YV12A is the same as YV12 but with a
+  // following alpha plane that is aligned and sized in the same manner as the

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

How about: 

YV12A is the same as YV12, but with an additional alpha plane that has the same
size and alignment as the Y plane.

[vignesh, 2013/02/25 23:33:14]

Done.

+  // Y plane.
+
   size_t y_stride = RoundUp(row_bytes(VideoFrame::kYPlane),
                             kFrameSizeAlignment);
   size_t uv_stride = RoundUp(row_bytes(VideoFrame::kUPlane),
                              kFrameSizeAlignment);
   // The *2 here is because some formats (e.g. h264) allow interlaced coding,
   // and then the size needs to be a multiple of two macroblocks (vertically).
   // See libavcodec/utils.c:avcodec_align_dimensions2().
   size_t y_height = RoundUp(coded_size_.height(), kFrameSizeAlignment * 2);
-  size_t uv_height = format_ == VideoFrame::YV12 ? y_height / 2 : y_height;
+  size_t uv_height = (format_ == VideoFrame::YV12 ||
+                      format_ == VideoFrame::YV12A) ?
+                              y_height / 2 : y_height;
   size_t y_bytes = y_height * y_stride;
   size_t uv_bytes = uv_height * uv_stride;
+  size_t a_bytes = format_ == VideoFrame::YV12A ? y_bytes : 0;
 
   // The extra line of UV being allocated is because h264 chroma MC
   // overreads by one line in some cases, see libavcodec/utils.c:
   // avcodec_align_dimensions2() and libavcodec/x86/h264_chromamc.asm:
   // put_h264_chroma_mc4_ssse3().
   uint8* data = reinterpret_cast<uint8*>(
       base::AlignedAlloc(
-          y_bytes + (uv_bytes * 2 + uv_stride) + kFrameSizePadding,
+          y_bytes + (uv_bytes * 2 + uv_stride) + a_bytes + kFrameSizePadding,
           kFrameAddressAlignment));
   no_longer_needed_cb_ = base::Bind(&ReleaseData, data);
   COMPILE_ASSERT(0 == VideoFrame::kYPlane, y_plane_data_must_be_index_0);
   data_[VideoFrame::kYPlane] = data;
   data_[VideoFrame::kUPlane] = data + y_bytes;
   data_[VideoFrame::kVPlane] = data + y_bytes + uv_bytes;
   strides_[VideoFrame::kYPlane] = y_stride;
   strides_[VideoFrame::kUPlane] = uv_stride;
   strides_[VideoFrame::kVPlane] = uv_stride;
+  if (format_ == YV12A) {
+    data_[VideoFrame::kAPlane] = data + y_bytes + (2 * uv_bytes);
+    strides_[VideoFrame::kAPlane] = y_stride;
+  }
 }
 
 VideoFrame::VideoFrame(VideoFrame::Format format,
                        const gfx::Size& coded_size,
                        const gfx::Rect& visible_rect,
                        const gfx::Size& natural_size,
                        base::TimeDelta timestamp)
     : format_(format),
       coded_size_(coded_size),
       visible_rect_(visible_rect),
@@ skipping 12 matching lines @@
 
 bool VideoFrame::IsValidPlane(size_t plane) const {
   switch (format_) {
     case RGB32:
       return plane == kRGBPlane;
 
     case YV12:
     case YV16:
       return plane == kYPlane || plane == kUPlane || plane == kVPlane;
 
+    case YV12A:
+      return plane == kYPlane || plane == kUPlane || plane == kVPlane ||
+              plane == kAPlane;

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

Fix indent.

[vignesh, 2013/02/25 23:33:14]

Done.

+
     case NATIVE_TEXTURE:
       NOTREACHED() << "NATIVE_TEXTUREs don't use plane-related methods!";
       return false;
 
     default:
       break;
   }
 
   // Intentionally leave out non-production formats.
   NOTREACHED() << "Unsupported video frame format: " << format_;
   return false;
 }
 
 int VideoFrame::stride(size_t plane) const {
   DCHECK(IsValidPlane(plane));
   return strides_[plane];
 }
 
 int VideoFrame::row_bytes(size_t plane) const {
   DCHECK(IsValidPlane(plane));
   int width = coded_size_.width();
   switch (format_) {
     // 32bpp.
     case RGB32:
       return width * 4;
 
     // Planar, 8bpp.
     case YV12:
     case YV16:
-      if (plane == kYPlane)
+    case YV12A:
+      if (plane == kYPlane || plane == kAPlane)
         return width;
       return RoundUp(width, 2) / 2;
 
     default:
       break;
   }
 
   // Intentionally leave out non-production formats.
   NOTREACHED() << "Unsupported video frame format: " << format_;
   return 0;
 }
 
 int VideoFrame::rows(size_t plane) const {
   DCHECK(IsValidPlane(plane));
   int height = coded_size_.height();
   switch (format_) {
     case RGB32:
     case YV16:
       return height;
 
     case YV12:
-      if (plane == kYPlane)
+    case YV12A:
+      if (plane == kYPlane || plane == kAPlane)
         return height;
       return RoundUp(height, 2) / 2;
 
     default:
       break;
   }
 
   // Intentionally leave out non-production formats.
   NOTREACHED() << "Unsupported video frame format: " << format_;
   return 0;
@@ skipping 24 matching lines @@
       break;
     for (int row = 0; row < rows(plane); ++row) {
       base::MD5Update(context, base::StringPiece(
           reinterpret_cast<char*>(data(plane) + stride(plane) * row),
           row_bytes(plane)));
     }
   }
 }
 
 }  // namespace media