Fix DCHECKs in V4l2VideoDevice.

content/common/gpu/media/v4l2_video_device.cc

 // Copyright 2014 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 <linux/videodev2.h>
 
 #include "base/numerics/safe_conversions.h"
 #include "content/common/gpu/media/exynos_v4l2_video_device.h"
 #include "content/common/gpu/media/tegra_v4l2_video_device.h"
 
@@ skipping 88 matching lines @@
     bytesperline = base::checked_cast<int>(format.fmt.pix.bytesperline);
     sizeimage = base::checked_cast<int>(format.fmt.pix.sizeimage);
     visible_size.SetSize(base::checked_cast<int>(format.fmt.pix.width),
                          base::checked_cast<int>(format.fmt.pix.height));
     frame_format =
         V4L2Device::V4L2PixFmtToVideoFrameFormat(format.fmt.pix.pixelformat);
   }
 
   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";
     return coded_size;
   }
 
   // Round up sizeimage to full bytesperlines. sizeimage does not have to be
   // a multiple of bytesperline, as in V4L2 terms it's just a byte size of
   // the buffer, unrelated to its payload.
   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.
   DCHECK(gfx::Rect(coded_size).Contains(gfx::Rect(visible_size)));
 
   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.

   }
 
   return coded_size;
 }
 
 }  //  namespace content