framegrab 0.4.4

Easily grab frames from cameras or streams

FrameGrab by Groundlight

A user-friendly library for grabbing images from cameras or streams

FrameGrab is an open-source Python library designed to make it easy to grab frames (images) from cameras or streams. The library supports generic USB cameras (such as webcams), RTSP streams, Basler USB cameras, Basler GigE cameras, and Intel RealSense depth cameras.

FrameGrab also provides basic motion detection functionality. FrameGrab requires Python 3.7 or higher.

Table of Contents

• Installation
• Usage
• Examples
• Contributing
• License

Installation

To install the FrameGrab library, simply run:

pip install framegrab

Optional Dependencies

To use a Basler USB or GigE camera, you must separately install the pypylon package.

Similarly, to use Intel RealSense cameras, you must install pyrealsense2.

If you don't intend to use these camera types, you don't need to install these extra packages.

Usage

Command line interface (CLI)

There is a simple CLI for framegrab to discover and preview configurations.

framegrab

lists the sub-commands, including autodiscover and preview.

Frame Grabbing

Frame Grabbers are defined by a configuration dict which is usually stored as YAML. The configuration combines the camera type, the camera ID, and the camera options. The configuration is passed to the FrameGrabber.create_grabber method to create a grabber object. The grabber object can then be used to grab frames from the camera.

config can contain many details and settings about your camera, but only input_type is required. Available input_type options are: generic_usb, rtsp, realsense, and basler.

Here's an example of a single USB camera configured with several options:

config = """
name: Front Door Camera
input_type: generic_usb
id:
  serial_number: 23432570
options:
    resolution:
        height: 1080
        width: 1920
    zoom:
        digital: 1.5
"""

grabber = FrameGrabber.create_grabber_yaml(config)

To get a frame, simply run:

frame = grabber.grab()

You can also change the options after the grabber is created.

new_options = {
    'resolution': {
        'height': 480,
        'width': 640,
    },
    'crop': {
        'relative': {
            'top': .1,
            'bottom': .9,
            'left': .1,
            'right': .9,
        }
    }
}

grabber.apply_options(new_options)

When you are done with the camera, release the resource by running:

grabber.release()

You might have several cameras that you want to use in the same application. In this case, you can load the configurations from a yaml file and use FrameGrabber.create_grabbers.

If you have multiple cameras of the same type plugged in, it's recommended that you include serial numbers in the configurations; this ensures that each configuration is paired with the correct camera. If you don't provide serial numbers in your configurations, configurations will be paired with cameras in a sequential manner.

Below is a sample yaml file containing configurations for three different cameras.

GL_CAMERAS: |
  - name: on robot arm
    input_type: realsense
    options: 
      depth:
        side_by_side: 1
      crop:
        relative:
          right: .8
  - name: conference room
      input_type: rtsp
      id: 
        rtsp_url: rtsp://admin:password@192.168.1.20/cam/realmonitor?channel=1&subtype=0
      options:
        crop:
          pixels:
            top: 350
            bottom: 1100
            left: 1100
            right: 2000
  - name: workshop
    input_type: generic_usb
    id:
      serial_number: B77D3A8F

You can load the configurations from the yaml file and use the cameras in the following manner.

from framegrab import FrameGrabber
import yaml

# load the configurations from yaml
config_path = 'camera_config.yaml'
with open(config_path, 'r') as f:
    data = yaml.safe_load(f)
    configs = yaml.safe_load(data['GL_CAMERAS'])

# create the grabbers
grabbers = FrameGrabber.create_grabbers(configs)

for grabber in grabbers.values():
    print(grabber.config)
    frame = grabber.grab()
    display_image(frame) # substitute this line for your preferred method of displaying images, such as cv2.imshow
    grabber.release()

Configurations

The table below shows all available configurations and the cameras to which they apply.

Configuration Name	Example	Generic USB	RTSP	Basler	Realsense
name	On Robot Arm	optional	optional	optional	optional
input_type	generic_usb	required	required	required	required
id.serial_number	23458234	optional	-	optional	optional
id.rtsp_url	rtsp://…	-	required	-	-
options.resolution.height	480	optional	-	-	optional
options.resolution.width	640	optional	-	-	optional
options.zoom.digital	1.3	optional	optional	optional	optional
options.crop.pixels.top	100	optional	optional	optional	optional
options.crop.pixels.bottom	400	optional	optional	optional	optional
options.crop.pixels.left	100	optional	optional	optional	optional
options.crop.pixels.right	400	optional	optional	optional	optional
options.crop.relative.top	0.1	optional	optional	optional	optional
options.crop.relative.bottom	0.9	optional	optional	optional	optional
options.crop.relative.left	0.1	optional	optional	optional	optional
options.crop.relative.right	0.9	optional	optional	optional	optional
options.depth.side_by_side	1	-	-	-	optional
options.num_90_deg_rotations	2	optional	optional	optional	optional

In addition to the configurations in the table above, you can set any Basler camera property by including options.basler.<BASLER PROPERTY NAME>. For example, it's common to set options.basler.PixelFormat to RGB8.

Autodiscovery

Autodiscovery automatically connects to all cameras that are plugged into your machine or discoverable on the network, including generic_usb, realsense and basler cameras. Default configurations will be loaded for each camera. Please note that RTSP streams cannot be discovered in this manner; RTSP URLs must be specified in the configurations.

Autodiscovery is great for simple applications where you don't need to set any special options on your cameras. It's also a convenient method for finding the serial numbers of your cameras (if the serial number isn't printed on the camera).

grabbers = FrameGrabber.autodiscover()

# Print some information about the discovered cameras
for grabber in grabbers.values():
    print(grabber.config)

    grabber.release()

Motion Detection

To use the built-in motion detection functionality, first create a MotionDetector object, specifying the percentage threshold for motion detection:

from framegrab import MotionDetector

motion_threshold = 1.0
m = MotionDetector(pct_threshold=motion_threshold)

The motion threshold is defined as the detection threshold for motion detection, in terms of the percentage of changed pixels. The default value is 1.0 (which means 1%).

Then, use the motion_detected() method with a captured frame to check if motion has been detected:

if m.motion_detected(frame):
    print("Motion detected!")

Examples

Here's an example of using the FrameGrab library to continuously capture frames and detect motion from a video stream:

from framegrab import FrameGrabber, MotionDetector

motion_threshold = 1.0

config = {
    'input_type': 'webcam',
}
grabber = FrameGrabber.create_grabber(config)
m = MotionDetector(pct_threshold=motion_threshold)

while True:
    frame = grabber.grab()
    if frame is None:
        print("No frame captured!")
        continue

    if m.motion_detected(frame):
        print("Motion detected!")

Contributing

We welcome contributions to FrameGrab! If you would like to contribute, please follow these steps:

1. Fork the repository
2. Create a new branch for your changes
3. Commit your changes to the branch
4. Open a pull request

License

FrameGrab is released under the MIT License. For more information, please refer to the LICENSE.txt file.