/// <summary>
/// Queries the device for information about each requested buffer.
/// </summary>
/// <param name="req">Struct with information about the request buffers.</param>
private void fetchBuffers(v4l2_requestbuffers req)
{
for (uint i = 0; i < req.count; i++)
{
v4l2_buffer buffer = new v4l2_buffer();
buffer.index = i;
buffer.type = req.type;
buffer.memory = req.memory;
if (ioControl.QueryBuffer(ref buffer) < 0)
{
throw new Exception("VIDIOC_QUERYBUF");
}
buffers.Add(new Analog.Buffer(this, buffer));
}
}
/// <summary>
/// Requests a given number of buffers for mmap data transfer.
/// </summary>
private void requestBuffers()
{
v4l2_requestbuffers req = new v4l2_requestbuffers();
req.count = bufferCount;
req.type = v4l2_buf_type.VideoCapture;
req.memory = v4l2_memory.MemoryMapping;
if (ioControl.RequestBuffers(ref req) < 0)
{
throw new Exception("VIDIOC_REQBUFS");
}
if (req.count < bufferCount)
{
throw new Exception("VIDIOC_REQBUFS [count]");
}
fetchBuffers(req);
}
private unsafe V4l2FrameBuffer[] ApplyFrameBuffers()
{
// Apply for buffers, use memory mapping
v4l2_requestbuffers req = new v4l2_requestbuffers
{
count = BufferCount,
type = v4l2_buf_type.V4L2_BUF_TYPE_VIDEO_CAPTURE,
memory = v4l2_memory.V4L2_MEMORY_MMAP
};
V4l2Struct(VideoSettings.VIDIOC_REQBUFS, ref req);
// Mapping the applied buffer to user space
V4l2FrameBuffer[] buffers = new V4l2FrameBuffer[BufferCount];
for (uint i = 0; i < BufferCount; i++)
{
v4l2_buffer buffer = new v4l2_buffer
{
index = i,
type = v4l2_buf_type.V4L2_BUF_TYPE_VIDEO_CAPTURE,
memory = v4l2_memory.V4L2_MEMORY_MMAP
};
V4l2Struct(VideoSettings.VIDIOC_QUERYBUF, ref buffer);
buffers[i].Length = buffer.length;
buffers[i].Start = Interop.mmap(IntPtr.Zero, (int)buffer.length, MemoryMappedProtections.PROT_READ | MemoryMappedProtections.PROT_WRITE, MemoryMappedFlags.MAP_SHARED, _deviceFileDescriptor, (int)buffer.m.offset);
}
// Put the buffer in the processing queue
for (uint i = 0; i < BufferCount; i++)
{
v4l2_buffer buffer = new v4l2_buffer
{
index = i,
type = v4l2_buf_type.V4L2_BUF_TYPE_VIDEO_CAPTURE,
memory = v4l2_memory.V4L2_MEMORY_MMAP
};
V4l2Struct(VideoSettings.VIDIOC_QBUF, ref buffer);
}
return(buffers);
}
public static extern int ioctl(int fd, UInt64 request, ref v4l2_requestbuffers req);
public static extern int ioctl(int fd, UInt64 request, ref v4l2_requestbuffers req);
/// <summary>
/// Calls VIDIOC_REQBUFS.
/// </summary>
public int RequestBuffers(ref v4l2_requestbuffers req)
{
return(ioctl(deviceHandle, v4l2_operation.RequestBuffers, ref req));
}
ioctl(int device, v4l2_operation request, ref v4l2_requestbuffers argp);
