VisualApplets
Operator Reference

Operator Library: Memory

The main feature of this operator is that it buffers a sequence of SequenceLength successive input images. This sequence is output simultaneously. Moreover, a region-of-interest (ROI) feature is included.

This operator buffers the image stream in the Frame Grabber RAM (DRAM). One VisualApplets resource of type RAM is required (see 'Allocation of Device Resources').

For information on the latency of the operator, see Table 43, 'Individual Latencies of the Operators in Library Memory'.

The simultaneous output of the image sequence is performed by using a kernel of SequenceLength columns. Each kernel component represents one image of the sequence i.e. corresponds to the image sequence number. For example at a sequence length of three, input image 0 will be output at kernel index 0, image 1 on kernel index 1, image 2 on kernel index 2. Next, the operator continuous with the next sequence, i.e. input image 3 will be output on kernel index 0, etc.

The operator does not change the bandwidth. It keeps the bandwidth constant for reading and writing. However the frame rate of the output images is 1/SequenceLength of the frame rate at the input. However, the output image is N times larger (due to the kernel) than a single input image.

The operator works like a FIFO buffer. As soon as enough images are buffered to generate a sequence, the operator will output the sequence. During this period, the next images are stored in the buffer.

Using parameters XOffset, XLength, YOffset and YLength the ROI size can be defined.

	No Filllevel and Flow Control
	The operator does not include parameters to check the fill level and no parameter to check for overflows. Moreover, no InfiniteSource parameter is included. The operator always assumes an infinite source at its input. It is not possible to check if the operator is in an overflow condition. See 'Infinite Sources / Connecting Cameras' for more information on flow control.

Bandwidth Optimization

The theoretical bandwidth [bits/second] going through an operator that uses the Frame Grabber RAM (DRAM) is calculated in accord with the following formula:

However, the actual bandwidth is always less than the theoretical bandwidth due to the DRAM efficiency.

The maximum bandwidth going through the operator is reached if the product of Bit Width and Parallelism is equal to the internal RAM Port Width.

	Platform-specific values
	RAM Port Width and System Clock are platform-specific. See Appendix. Device Resources for detailed information on your individual platform.

Supported Link Format

Link Parameter	Input Link I	Output Link O
Bit Width	[1, 64]	as I
Arithmetic	{unsigned, signed}	as I
Parallelism	any	as I
Kernel Columns	1 SequenceLength	as I
Kernel Rows	1	as I
Img Protocol	VALT_IMAGE2D	as I
Color Format	any	as I
Color Flavor	any	as I
Max. Img Width	65535	as I
Max. Img Height	any	as I

	The range of the input bit width is [1, 64] for unsigned inputs. For signed inputs, the range is [2, 64]. For unsigned color inputs, the range is [3, 63] and for signed color, the range is [6, 63].
	The product of the bit width and the parallelism must not exceed the native ram data width. Check Appendix. Device Resources for more information.