Configuring a Video Capture Device

Table of Contents

• Open a Device
• Configure the Resolution
• Define ROI Origin
• Set an Exposure Time

This section contains a small example program showing how to configure a video capture device through the IC4_PROPERTY_MAP interface.

The article Accessing Device Properties explains the capabilities of the property interface in detail.

Open a Device

For demonstration purposes, we open the first available video capture device:

// Create a grabber object
struct IC4_GRABBER* grabber = NULL;
ic4_grabber_create(&grabber);
 
// Find the first available video capture device
struct IC4_DEVICE_ENUM* enumerator = NULL;
ic4_devenum_create(&enumerator);
ic4_devenum_update_device_list(enumerator);
struct IC4_DEVICE_INFO* info = NULL;
ic4_devenum_get_devinfo(enumerator, 0, &info);
ic4_devenum_unref(enumerator);
 
// Open it
ic4_grabber_device_open(grabber, info);
ic4_devinfo_unref(info);

Configure the Resolution

Next, we configure the device to output Mono8 data with a ROI of 640x480:

IC4_PROPERTY_MAP* map = NULL;
ic4_grabber_device_get_property_map(grabber, &map);
 
// Configure the device to output images in the Mono8 pixel format
ic4_propmap_set_value_int64(map, IC4_PROPID_PIXELFORMAT, IC4_PIXELFORMAT_Mono8);
 
// Set the resolution to 640x480
ic4_propmap_set_value_int64(map, IC4_PROPID_WIDTH, 640);
ic4_propmap_set_value_int64(map, IC4_PROPID_HEIGHT, 480);

Define ROI Origin

Then, the origin of the ROI is moved to the top left corner of the sensor:

// Set the origin of the ROI to the top-left corner of the sensor
ic4_propmap_set_value_string(map, IC4_PROPID_OFFSET_AUTO_CENTER, "Off");
ic4_propmap_set_value_int64(map, IC4_PROPID_OFFSET_X, 0);
ic4_propmap_set_value_int64(map, IC4_PROPID_OFFSET_Y, 0);

Set an Exposure Time

Finally, we configure the device to a fixed exposure time of 5ms and enable automatic gain control:

// Configure the exposure time to 5ms (5000µs)
ic4_propmap_set_value_string(map, IC4_PROPID_EXPOSURE_AUTO, "Off");
ic4_propmap_set_value_double(map, IC4_PROPID_EXPOSURE_TIME, 5000.0);
 
// Enable GainAuto
ic4_propmap_set_value_string(map, IC4_PROPID_GAIN_AUTO, "Continuous");

At the end of the program, references to objects have to be released:

// Clean up property map and grabber objects
ic4_propmap_unref(map);
ic4_grabber_unref(grabber);