Linux Video Capture: Add V4L2VideoCaptureDelegate{Single,Multi}Plane.

media/video/capture/linux/v4l2_capture_delegate_multi_plane.cc

+// Copyright 2015 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/video/capture/linux/v4l2_capture_delegate_multi_plane.h"
+
+#include <sys/mman.h>
+
+namespace media {
+
+V4L2CaptureDelegateMultiPlane::V4L2CaptureDelegateMultiPlane(
+    const VideoCaptureDevice::Name& device_name,
+    const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
+    int power_line_frequency)
+    : V4L2VideoCaptureDelegate(device_name,
+                               v4l2_task_runner,
+                               power_line_frequency) {
+}
+
+V4L2CaptureDelegateMultiPlane::~V4L2CaptureDelegateMultiPlane() {
+}
+
+scoped_refptr<V4L2VideoCaptureDelegate::BufferTracker>
+V4L2CaptureDelegateMultiPlane::CreateBufferTracker() const {
+  return make_scoped_refptr(new BufferTrackerMPlane());
+}
+
+bool V4L2CaptureDelegateMultiPlane::FillV4L2Format(
+    v4l2_format* format,
+    uint32_t width,
+    uint32_t height,
+    uint32_t pixelformat_fourcc) const {
+  format->fmt.pix_mp.width = width;
+  format->fmt.pix_mp.height = height;
+  format->fmt.pix_mp.pixelformat = pixelformat_fourcc;
+
+  const size_t num_v4l2_planes =
+      V4L2VideoCaptureDelegate::GetNumPlanesForFourCc(pixelformat_fourcc);
+  if (num_v4l2_planes == 0u)
+    return false;
+  DCHECK_LE(num_v4l2_planes, static_cast<size_t>(VIDEO_MAX_PLANES));
+  format->fmt.pix_mp.num_planes = num_v4l2_planes;
+
+  v4l2_planes_.resize(num_v4l2_planes);
+  return true;
+}
+
+void V4L2CaptureDelegateMultiPlane::FinishFillingV4L2Buffer(
+    v4l2_buffer* buffer) const {
+  buffer->type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  buffer->length = v4l2_planes_.size();
+
+  static const struct v4l2_plane empty_plane = {};
+  std::fill(v4l2_planes_.begin(), v4l2_planes_.end(), empty_plane);
+  buffer->m.planes = v4l2_planes_.data();
+}
+
+void V4L2CaptureDelegateMultiPlane::SendBuffer(
+    const scoped_refptr<BufferTracker>& buffer_tracker) const {
+  DCHECK_EQ(capture_format().pixel_format, PIXEL_FORMAT_I420);
+  const size_t y_stride =
+      buffer_tracker->GetPlaneLength(0) / capture_format().frame_size.height();

[Pawel Osciak, 2015/03/20 00:56:06]

If you need stride, then you should use bytesperline from the
v4l2_pix_format_mplane struct. And have some kind of dcheck that it's what you
expect.

[mcasas, 2015/03/20 03:01:20]

Done.

+  const size_t u_stride = buffer_tracker->GetPlaneLength(1) /
+                          ((capture_format().frame_size.height() + 1) / 2);
+  const size_t v_stride = buffer_tracker->GetPlaneLength(2) /
+                          ((capture_format().frame_size.height() + 1) / 2);
+  client()->OnIncomingCapturedYuvData(buffer_tracker->GetPlaneStart(0),
+                                      buffer_tracker->GetPlaneStart(1),
+                                      buffer_tracker->GetPlaneStart(2),
+                                      y_stride,

[Pawel Osciak, 2015/03/20 00:56:06]

The prototype of VideoCaptureDevice::Client::OnIncomingCapturedYuvData() has
lengths.

[mcasas, 2015/03/20 03:01:20]

Done.

+                                      u_stride,
+                                      v_stride,
+                                      capture_format(),
+                                      rotation(),
+                                      base::TimeTicks::Now());
+}
+
+bool V4L2CaptureDelegateMultiPlane::BufferTrackerMPlane::Init(
+    int fd,
+    const v4l2_buffer& buffer) {
+  for (size_t p = 0; p < buffer.length; ++p) {
+    // Some devices require mmap() to be called with both READ and WRITE.
+    // See http://crbug.com/178582.
+    void* const start =
+        mmap(NULL, buffer.m.planes[p].length, PROT_READ | PROT_WRITE,
+             MAP_SHARED, fd, buffer.m.planes[p].m.mem_offset);
+    if (start == MAP_FAILED) {
+      DLOG(ERROR) << "Error mmap()ing a V4L2 buffer into userspace";
+      return false;
+    }
+    AddMmapedPlane(static_cast<uint8_t*>(start), buffer.m.planes[p].length);
+    DVLOG(3) << "Mmap()ed plane #" << p << " of " << GetPlaneLength(p) << "B";
+  }
+  return true;
+}
+
+}  // namespace media