/// <summary>
/// Creates a buffer to be used with Video4Linux streaming I/O.
/// </summary>
/// <param name="adapter">The parental Video4Linux device.</param>
/// <param name="buffer">The struct holding the buffer information.</param>
internal Buffer(Analog.Adapter adapter, v4l2_buffer buffer)
{
this.adapter = adapter;
this.buffer = buffer;
mapMemory();
}
private unsafe NewImageBufferReadyEventArgs GetFrameDataPooled(V4l2FrameBuffer *buffers)
{
// Get one frame from the buffer
v4l2_buffer frame = new v4l2_buffer
{
type = v4l2_buf_type.V4L2_BUF_TYPE_VIDEO_CAPTURE,
memory = v4l2_memory.V4L2_MEMORY_MMAP,
};
V4l2Struct(V4l2Request.VIDIOC_DQBUF, ref frame);
// Get data from pointer
IntPtr intptr = buffers[frame.index].Start;
var length = (int)buffers[frame.index].Length;
byte[] dataBuffer = Array.Empty <byte>();
if (ImageBufferPoolingEnabled)
{
dataBuffer = ArrayPool <byte> .Shared.Rent(length);
}
else
{
dataBuffer = new byte[length];
}
Marshal.Copy(source: intptr, destination: dataBuffer, startIndex: 0, length: (int)buffers[frame.index].Length);
// Requeue the buffer
V4l2Struct(V4l2Request.VIDIOC_QBUF, ref frame);
return(new NewImageBufferReadyEventArgs(dataBuffer, length));
}
/// HACK: we should read until we reached count
/// HACK: offset is ignored
private int readMM(byte[] buffer, int offset, int count)
{
if (!adapter.Capabilities.Contains(AdapterCapability.Streaming))
{
throw new Exception("Device does not support streaming.");
}
v4l2_buffer buf = new v4l2_buffer();
buf.type = adapter.Buffers[0].Type;
buf.memory = adapter.Buffers[0].Memory;
// read one image
if (adapter.IoControl.DequeueBuffer(ref buf) == 0)
{
Analog.Buffer dbuf = adapter.Buffers[(int)buf.index];
// max length = buffer length
if ((int)dbuf.Length < count)
{
count = (int)dbuf.Length;
}
// copy all the data from the buffer
Marshal.Copy(dbuf.Start, buffer, 0, count);
// re-enqueue the buffer
dbuf.Enqueue();
return(count);
}
return(0);
}
/// <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));
}
}
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);
}
private unsafe byte[] GetFrameData(V4l2FrameBuffer *buffers)
{
// Get one frame from the buffer
v4l2_buffer frame = new v4l2_buffer
{
type = v4l2_buf_type.V4L2_BUF_TYPE_VIDEO_CAPTURE,
memory = v4l2_memory.V4L2_MEMORY_MMAP,
};
V4l2Struct(VideoSettings.VIDIOC_DQBUF, ref frame);
// Get data from pointer
IntPtr intptr = buffers[frame.index].Start;
byte[] dataBuffer = new byte[buffers[frame.index].Length];
Marshal.Copy(source: intptr, destination: dataBuffer, startIndex: 0, length: (int)buffers[frame.index].Length);
// Requeue the buffer
V4l2Struct(VideoSettings.VIDIOC_QBUF, ref frame);
return(dataBuffer);
}
public static extern int ioctl(int fd, UInt64 request, ref v4l2_buffer buf);
public static extern int ioctl(int fd, UInt64 request, ref v4l2_buffer buf);
/// <summary>
/// Calls VIDIOC_QBUF.
/// </summary>
public int EnqueueBuffer(ref v4l2_buffer buffer)
{
return(ioctl(deviceHandle, v4l2_operation.EnqueueBuffer, ref buffer));
}
/// <summary>
/// Calls VIDIOC_QUERYBUF.
/// </summary>
public int QueryBuffer(ref v4l2_buffer buffer)
{
return(ioctl(deviceHandle, v4l2_operation.QueryBuffer, ref buffer));
}
ioctl(int device, v4l2_operation request, ref v4l2_buffer argp);
