CSCore Camera API

CSCore is WPILib’s camera handling library, providing efficient camera capture, processing, and streaming for FRC robots and vision coprocessors.

Overview

CSCore provides:

USB camera capture (webcams, PS3 Eye, etc.)
HTTP MJPEG streaming
Network camera sources (Axis, other MJPEG streams)
OpenCV integration for vision processing
Multi-camera support with automatic bandwidth management
Low-latency video streaming

Architecture

Core Concepts

Video Sources

Camera inputs (USB, network, OpenCV)

Video Sinks

Stream outputs (MJPEG server, OpenCV)

Video Properties

Configure resolution, framerate, exposure

OpenCV Integration

Process frames with OpenCV

Basic Usage

Java API

import edu.wpi.first.cameraserver.CameraServer;
import edu.wpi.first.cscore.*;

public class Robot extends TimedRobot {
  @Override
  public void robotInit() {
    // Simple camera streaming
    CameraServer.startAutomaticCapture();
    
    // Or with more control
    UsbCamera camera = CameraServer.startAutomaticCapture("Camera", 0);
    camera.setResolution(320, 240);
    camera.setFPS(30);
  }
}

C++ API

#include <cameraserver/CameraServer.h>

class Robot : public frc::TimedRobot {
 public:
  void RobotInit() override {
    // Simple camera streaming
    frc::CameraServer::StartAutomaticCapture();
    
    // Or with more control
    cs::UsbCamera camera = frc::CameraServer::StartAutomaticCapture("Camera", 0);
    camera.SetResolution(320, 240);
    camera.SetFPS(30);
  }
};

Video Sources

USB Camera

Capture from USB cameras.

import edu.wpi.first.cscore.*;

// Create USB camera
UsbCamera camera = new UsbCamera("Camera", 0);  // Device 0

// Or by path
UsbCamera camera2 = new UsbCamera("Camera", "/dev/video0");

// Configure camera
camera.setResolution(640, 480);
camera.setFPS(30);
camera.setBrightness(50);  // 0-100
camera.setExposureManual(20);  // Manual exposure
// or
camera.setExposureAuto();  // Automatic exposure

// Get camera info
VideoMode mode = camera.getVideoMode();
int width = mode.width;
int height = mode.height;
VideoMode.PixelFormat format = mode.pixelFormat;
int fps = mode.fps;

// Enumerate available modes
VideoMode[] modes = camera.enumerateVideoModes();
for (VideoMode m : modes) {
    System.out.println(m.width + "x" + m.height + " @ " + m.fps);
}

#include <cscore_cpp.h>

// Create USB camera
cs::UsbCamera camera{"Camera", 0};

// Configure camera
camera.SetResolution(640, 480);
camera.SetFPS(30);
camera.SetBrightness(50);
camera.SetExposureManual(20);

// Get camera info
cs::VideoMode mode = camera.GetVideoMode();
int width = mode.width;
int height = mode.height;
cs::VideoMode::PixelFormat format = mode.pixelFormat;
int fps = mode.fps;

// Enumerate modes
std::vector<cs::VideoMode> modes = camera.EnumerateVideoModes();
for (const auto& m : modes) {
  fmt::print("{}x{} @ {}\n", m.width, m.height, m.fps);
}

HTTP Camera

Stream from network MJPEG cameras.

// Create HTTP camera (Axis camera, IP camera, etc.)
HttpCamera axisCam = new HttpCamera(
    "Axis Camera",
    "http://10.12.34.11/mjpg/video.mjpg"
);

// Multiple URLs for failover
HttpCamera multiCam = new HttpCamera(
    "Multi Camera",
    new String[]{
        "http://10.12.34.11/mjpg/video.mjpg",
        "http://10.12.34.12/mjpg/video.mjpg"
    }
);

OpenCV Source

Create video source from processed frames.

// Create CV source
CvSource outputStream = CameraServer.putVideo("Processed", 640, 480);

// Put OpenCV frame
Mat processedFrame = new Mat();
outputStream.putFrame(processedFrame);

// Create CV source
cs::CvSource outputStream = frc::CameraServer::PutVideo("Processed", 640, 480);

// Put OpenCV frame
cv::Mat processedFrame;
outputStream.PutFrame(processedFrame);

Video Sinks

MJPEG Server

Stream video over HTTP.

import edu.wpi.first.cscore.*;

// Create MJPEG server
MjpegServer server = new MjpegServer("Server", 8080);

// Set source
server.setSource(camera);

// Access at: http://roborio-1234-frc.local:8080/stream.mjpg

cs::MjpegServer server{"Server", 8080};
server.SetSource(camera);

CV Sink

Capture frames for OpenCV processing.

import edu.wpi.first.cscore.*;
import org.opencv.core.Mat;

// Create CV sink
CvSink cvSink = CameraServer.getVideo(camera);

// Capture frame
Mat frame = new Mat();
long frameTime = cvSink.grabFrame(frame);

if (frameTime == 0) {
    // Error occurred
    String error = cvSink.getError();
    System.err.println(error);
} else {
    // Process frame
    processFrame(frame);
}

cs::CvSink cvSink = frc::CameraServer::GetVideo(camera);

cv::Mat frame;
uint64_t frameTime = cvSink.GrabFrame(frame);

if (frameTime == 0) {
  fmt::print("Error: {}\n", cvSink.GetError());
} else {
  // Process frame
  ProcessFrame(frame);
}

Video Properties

Getting Properties

// Get all properties
VideoProperty[] props = camera.enumerateProperties();
for (VideoProperty prop : props) {
    System.out.println(prop.getName() + ": " + prop.get());
}

// Get specific property
VideoProperty brightness = camera.getProperty("brightness");
int value = brightness.get();

Setting Properties

// Common properties
camera.setBrightness(50);      // 0-100
camera.setWhiteBalanceAuto();  
camera.setWhiteBalanceManual(4000);  // Kelvin
camera.setExposureAuto();
camera.setExposureManual(20);  // Exposure time

// Generic property setting
VideoProperty prop = camera.getProperty("sharpness");
prop.set(75);

Property Info

VideoProperty prop = camera.getProperty("brightness");

System.out.println("Name: " + prop.getName());
System.out.println("Min: " + prop.getMin());
System.out.println("Max: " + prop.getMax());
System.out.println("Step: " + prop.getStep());
System.out.println("Default: " + prop.getDefault());
System.out.println("Current: " + prop.get());

Multiple Cameras

public class Robot extends TimedRobot {
  UsbCamera frontCamera;
  UsbCamera backCamera;
  VideoSource currentCamera;
  MjpegServer server;
  
  @Override
  public void robotInit() {
    // Create cameras
    frontCamera = new UsbCamera("Front", 0);
    backCamera = new UsbCamera("Back", 1);
    
    // Configure both
    frontCamera.setResolution(320, 240);
    backCamera.setResolution(320, 240);
    
    // Create server
    server = new MjpegServer("Server", 8080);
    
    // Start with front camera
    currentCamera = frontCamera;
    server.setSource(currentCamera);
  }
  
  public void switchCamera() {
    // Switch cameras
    if (currentCamera == frontCamera) {
      currentCamera = backCamera;
    } else {
      currentCamera = frontCamera;
    }
    server.setSource(currentCamera);
  }
}

OpenCV Integration

Vision Processing Thread

import edu.wpi.first.cscore.*;
import edu.wpi.first.cameraserver.CameraServer;
import org.opencv.core.*;
import org.opencv.imgproc.Imgproc;

public class VisionThread extends Thread {
  @Override
  public void run() {
    // Create camera
    UsbCamera camera = CameraServer.startAutomaticCapture();
    camera.setResolution(320, 240);
    camera.setFPS(30);
    
    // Create sinks/sources
    CvSink cvSink = CameraServer.getVideo();
    CvSource outputStream = CameraServer.putVideo("Processed", 320, 240);
    
    // Processing loop
    Mat frame = new Mat();
    Mat processed = new Mat();
    
    while (!Thread.interrupted()) {
      if (cvSink.grabFrame(frame) == 0) {
        continue;
      }
      
      // Process frame
      Imgproc.cvtColor(frame, processed, Imgproc.COLOR_BGR2GRAY);
      Imgproc.threshold(processed, processed, 100, 255, Imgproc.THRESH_BINARY);
      
      // Output processed frame
      outputStream.putFrame(processed);
    }
  }
}

// Start thread in robotInit()
new VisionThread().start();

C++ Vision Processing

#include <cscore_cpp.h>
#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <thread>

void VisionThread() {
  // Create camera
  cs::UsbCamera camera = frc::CameraServer::StartAutomaticCapture();
  camera.SetResolution(320, 240);
  camera.SetFPS(30);
  
  // Create sinks/sources
  cs::CvSink cvSink = frc::CameraServer::GetVideo();
  cs::CvSource outputStream = frc::CameraServer::PutVideo("Processed", 320, 240);
  
  // Processing loop
  cv::Mat frame;
  cv::Mat processed;
  
  while (true) {
    if (cvSink.GrabFrame(frame) == 0) {
      continue;
    }
    
    // Process frame
    cv::cvtColor(frame, processed, cv::COLOR_BGR2GRAY);
    cv::threshold(processed, processed, 100, 255, cv::THRESH_BINARY);
    
    // Output processed frame
    outputStream.PutFrame(processed);
  }
}

// Start thread in RobotInit()
std::thread visionThread(VisionThread);
visionThread.detach();

Camera Server

High-level API for common camera operations.

import edu.wpi.first.cameraserver.CameraServer;

// Automatic capture (simple)
CameraServer.startAutomaticCapture();

// With device number
UsbCamera camera = CameraServer.startAutomaticCapture(0);

// With name
UsbCamera camera2 = CameraServer.startAutomaticCapture("Front Camera", 0);

// Add switched camera
MjpegServer server = CameraServer.addSwitchedCamera("Switched");
server.setSource(camera1);  // Switch between cameras

// Get existing camera
VideoSource camera3 = CameraServer.getVideo("Front Camera");

Low-Level C API

For direct hardware access.

#include <cscore_c.h>

// Create camera
CS_Source camera = cscore::CreateUsbCameraDev("Camera", 0);

// Set properties
cscore::SetSourcePixelFormat(camera, CS_PIXFMT_MJPEG, NULL);
cscore::SetSourceResolution(camera, 640, 480, NULL);
cscore::SetSourceFPS(camera, 30, NULL);

// Create server
CS_Sink server = cscore::CreateMjpegServer("Server", "", 8080, NULL);
cscore::SetSinkSource(server, camera, NULL);

Pixel Formats

Format	Description	Use Case
`MJPEG`	Motion JPEG	High resolution, low CPU
`YUYV`	YUV 4:2:2	OpenCV processing
`RGB565`	16-bit RGB	Low bandwidth
`BGR`	OpenCV native	Direct OpenCV use
`GRAY`	Grayscale	Vision processing

Performance Tips

Resolution and Framerate

// Lower resolution = better performance
camera.setResolution(320, 240);  // Instead of 640x480

// Lower framerate = lower bandwidth
camera.setFPS(15);  // Instead of 30

// Use MJPEG for streaming (hardware compressed)
camera.setPixelFormat(PixelFormat.kMJPEG);

Vision Processing

// Reduce processing resolution
camera.setResolution(160, 120);  // Minimal for vision

// Use grayscale
camera.setPixelFormat(PixelFormat.kGray);

// Process every Nth frame
int frameCount = 0;
if (frameCount++ % 3 == 0) {
    processFrame(frame);
}

Common Cameras

Microsoft LifeCam HD-3000

UsbCamera camera = CameraServer.startAutomaticCapture();
camera.setResolution(320, 240);
camera.setFPS(30);
camera.setExposureManual(50);

PS3 Eye

UsbCamera camera = CameraServer.startAutomaticCapture();
camera.setResolution(320, 240);
camera.setFPS(60);  // Supports 60 FPS

Limelight

// Limelight is accessed via NetworkTables, not CSCore
NetworkTable table = NetworkTableInstance.getDefault().getTable("limelight");
double tx = table.getEntry("tx").getDouble(0.0);

Source Code

View the full source code on GitHub:

CameraServer

High-level camera API

WPINet

Network streaming backend

OpenCV

Vision processing library

Core Libraries

Math & Utilities

Networking & Vision

Command Framework

Simulation

Documentation Index

​Overview

​Architecture

​Core Concepts

Video Sources

Video Sinks

Video Properties

OpenCV Integration

​Basic Usage

​Java API

​C++ API

​Video Sources

​USB Camera

​HTTP Camera

​OpenCV Source

​Video Sinks

​MJPEG Server

​CV Sink

​Video Properties

​Getting Properties

​Setting Properties

​Property Info

​Multiple Cameras

​OpenCV Integration

​Vision Processing Thread

​C++ Vision Processing

​Camera Server

​Low-Level C API

​Pixel Formats

​Performance Tips

​Resolution and Framerate

​Vision Processing

​Common Cameras

​Microsoft LifeCam HD-3000

​PS3 Eye

​Limelight

​Source Code

​Related Documentation

CameraServer

WPINet

OpenCV

Overview

Architecture

Core Concepts

Basic Usage

Java API

C++ API

Video Sources

USB Camera

HTTP Camera

OpenCV Source

Video Sinks

MJPEG Server

CV Sink

Video Properties

Getting Properties

Setting Properties

Property Info

Multiple Cameras

OpenCV Integration

Vision Processing Thread

C++ Vision Processing

Camera Server

Low-Level C API

Pixel Formats

Performance Tips

Resolution and Framerate

Vision Processing

Common Cameras

Microsoft LifeCam HD-3000

PS3 Eye

Limelight

Source Code

Related Documentation