HV Counter

Count active dimensions of pixel stream

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Libraries:
Vision HDL Toolbox / Utilities

Description

The HV Counter block analyzes a video stream and returns the current count of lines per frame and pixels per line. The block also delays control signals of the pixel stream to correspond with the count result. Use this block for algorithms that use the location of a pixel within a frame or region of interest.

This waveform shows the pixel-stream control signals and resulting counter outputs for the first two lines of a video frame that has 10 pixels per line. The HV Counter block has a latency of two cycles to return the current counter values.

Examples

Pothole Detection

Extends the Generate Cartoon Images Using Bilateral Filtering example to include calculating a centroid and overlaying a centroid marker and text label on detected potholes.

Open Script

Ports

This block uses a bus for frame control signals associated with each pixel of a pixel stream. This interface enables the block to operate independently of image size and format. All Vision HDL Toolbox™ blocks use the same streaming interface. The block accepts and returns a bus containing five control signals. The control signals indicate the validity of each pixel and its location in the frame. For a full description of the interface, see Streaming Pixel Interface.

Input

ctrl — Control signals associated with pixel stream

pixelcontrol bus

The pixelcontrol bus contains five signals. The signals describe the validity of the pixel and its location in the frame. For more information, see Pixel Control Bus.

Data Types: bus

Output

hCount — Pixel location in line

positive integer

Pixel location within a line, returned as a positive integer. The block clears the pixel count at the start of each line. If the input pixels per line exceeds the size of the counter, the block returns a saturated value until the start of the next line.

Data Types: fixdt(0,ceil(log2(ActiveVideoLines)),0)

vCount — Line location in frame

positive integer

Line location within the frame or region of interest, returned as a positive integer. The block clears the line count at the start of each frame. If the input lines per frame exceeds the size of the counter, the block returns a saturated value until the start of the next frame.

Data Types: fixdt(0,ceil(log2(ActiveVideoLines)),0)

ctrl — Control signals associated with pixel stream

pixelcontrol bus

The pixelcontrol bus contains five signals. The signals describe the validity of the pixel and its location in the frame. For more information, see Pixel Control Bus.

Data Types: bus

Parameters

Active pixels per line — Maximum pixels per line

320 (default) | positive integer

Maximum pixels per line, specified as a positive integer. The block implements a pixel counter that has ceil(log2(ActivePixelsPerLine)) bits. For example, for a frame with 320 pixels per line, the counter has 9 bits. For a frame with 1024 pixels per line, the counter has 11 bits.

Active video lines — Maximum lines per frame

240 (default) | positive integer

Maximum lines per frame, specified as a positive integer. The block implements a line counter that has ceil(log2(ActiveVideoLines)) bits. For example, for a frame with 240 pixels per line, the counter has 8 bits. For a frame with 1080 pixels per line, the counter has 11 bits.

Algorithms

Performance

This table shows the resource use after synthesis of the block for the Xilinx^® Zynq^®-7000 SoC ZC706 Evaluation Kit with single-pixel uint8 input and the default parameter settings. The design achieves a clock frequency of 500 MHz.

Resource	Usage
Slice LUTs	43
Slice Registers	51
DSP48	0
Block RAM	0

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

This block supports C/C++ code generation for Simulink^® accelerator and rapid accelerator modes and for DPI component generation.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).

Version History

Introduced in R2019a