Fix DCHECKs in V4l2VideoDevice.

content/common/gpu/media/v4l2_video_device.cc

Index: content/common/gpu/media/v4l2_video_device.cc
diff --git a/content/common/gpu/media/v4l2_video_device.cc b/content/common/gpu/media/v4l2_video_device.cc
index e9c54229c787e7a4d59e04ec08a6564d8855a335..2237df3b51672a01dfc6ae70253eb4f90a0fbbfe 100644
--- a/content/common/gpu/media/v4l2_video_device.cc
+++ b/content/common/gpu/media/v4l2_video_device.cc
@@ -106,6 +106,11 @@ gfx::Size V4L2Device::CodedSizeFromV4L2Format(struct v4l2_format format) {
 
   int horiz_bpp =
       media::VideoFrame::PlaneHorizontalBitsPerPixel(frame_format, 0);
+  DVLOG(3) << "CodedSizeFromV4L2Format: bytesperline=" << bytesperline

[Pawel Osciak, 2014/08/18 07:52:03]

use __func__ or __FUNCTION__?

[wuchengli, 2014/08/18 09:09:00]

Done.

+           << ", sizeimage=" << sizeimage
+           << ", visible_size=" << visible_size.ToString() << ", frame_format="
+           << media::VideoFrame::FormatToString(frame_format)
+           << ", horiz_bpp=" << horiz_bpp;
   if (sizeimage == 0 || bytesperline == 0 || horiz_bpp == 0 ||
       (bytesperline * 8) % horiz_bpp != 0) {
     DLOG(ERROR) << "Invalid format provided";
@@ -118,6 +123,7 @@ gfx::Size V4L2Device::CodedSizeFromV4L2Format(struct v4l2_format format) {
   sizeimage = ((sizeimage + bytesperline - 1) / bytesperline) * bytesperline;
 
   coded_size.SetSize(bytesperline * 8 / horiz_bpp, sizeimage / bytesperline);
+  DVLOG(3) << "coded_size=" << coded_size.ToString();
 
   // Sanity checks. Calculated coded size has to contain given visible size
   // and fulfill buffer byte size requirements for each plane.
@@ -125,11 +131,9 @@ gfx::Size V4L2Device::CodedSizeFromV4L2Format(struct v4l2_format format) {
 
   if (V4L2_TYPE_IS_MULTIPLANAR(format.type)) {
     for (size_t i = 0; i < format.fmt.pix_mp.num_planes; ++i) {
-      DCHECK_LE(
-          format.fmt.pix_mp.plane_fmt[i].sizeimage,
-          media::VideoFrame::PlaneAllocationSize(frame_format, i, coded_size));
-      DCHECK_LE(format.fmt.pix_mp.plane_fmt[i].bytesperline,
-                base::checked_cast<__u32>(coded_size.width()));
+      DCHECK_EQ(format.fmt.pix_mp.plane_fmt[i].bytesperline,
+                base::checked_cast<__u32>(VideoFrame::RowBytes(
+                    i, frame_format, coded_size.width()));
     }

[Pawel Osciak, 2014/08/18 07:52:03]

I think we still wanted to check sizeimage >= PlaneAllocationSize? Maybe I'm
forgetting what the final conclusion that we reached was...

[wuchengli, 2014/08/18 09:09:00]

The conclusion was this should be removed. The problem is the driver has an
extra 256-byte padding. sizeimage is rounded up at line 123. So the |coded_size|
at is bigger than format.fmt.pix_mp.width and height. The result is sizeimage <
PlaneAllocationSize.

For example, format.fmt.pix_mp.width and height are 1920x1088.
format.fmt.pix_mp.plane_fmt[0].sizeimage is 2089216 (1920*1088+256). |sizeimage|
is rounded up and |coded_size| becomes 1920x1089. So
format.fmt.pix_mp.plane_fmt[i].sizeimage (2089216) is less than
PlaneAllocationSize (1920*1090=2092800).

We cannot round down |sizeimage| at line 123 because the client of VEA uses the
returned coded size to allocate the buffers. If we round down, the client will
allocate buffers smaller than needed.

   }