/// <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 static extern int ioctl(int device, v4l2_operation request, ref v4l2_requestbuffers argp);
/// <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 V4LBuffer(this, buffer));
}
}
/// <summary>
/// Calls VIDIOC_REQBUFS.
/// </summary>
public int RequestBuffers(ref v4l2_requestbuffers req)
{
return ioctl(deviceHandle, v4l2_operation.RequestBuffers, ref req);
}