Vcap

Introduction

Vcap is a library written in C that aims to make using the Video4Linux2 API simple. It was designed to make the common case of capturing frames using memory-mapped device buffers quick and easy.

Vcap was also written with computer vision applications in mind and thus allows setting camera controls that enhance or interfere with computer vision and image processing techniques. Vcap also includes a (growing) number of pixel format decoding functions, enabling seamless support for many devices.

In contrast with similar projects, Vcap is licensed under the LGPL v2.1 which permits it's use in commercial products.

This project also has C++ bindings.

Building and Installation

You must have CMake and a C compiler installed.

$ cmake . && make

To install:

$ make install

To generate documentation (if Doxygen is installed):

$ make doc

Example

This example grabs a raw frame, from the first camera on the bus, and stores it in a file:

#include <vcap/vcap.h>

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

/*
 * Grabs raw data from a camera and saves it to the file 'image.raw'
 */
int main(int argc, char* argv[]) {
	vcap_camera_t* cameras;
	
	int num_cameras = vcap_cameras(&cameras);
	
	if (num_cameras <= 0) {
		printf("No cameras found!\n");
		return -1;
	}
	
	//open the first camera found
	vcap_camera_t* camera = &cameras[0];
	
	if (-1 == vcap_open_camera(camera)) {
		printf("Error: %s\n", vcap_error());
		return -1;
	}
	
	//start capturing
	if (-1 == vcap_start_capture(camera)) {
		printf("Error: %s\n", vcap_error());
		return -1;
	}
	
	//some cameras require time to initialize
	sleep(3);
	
	//grab frame
	uint8_t* raw_buffer;
	
	int buffer_size = vcap_grab_frame(camera, &raw_buffer);
	
	if (-1 == buffer_size) {
		printf("Error: %s\n", vcap_error());
		return -1;
	}	
	
	//write frame to file
	FILE* file = fopen("image.raw", "wb");
			
	if (fwrite(raw_buffer, buffer_size, 1, file) != 1)
		printf("Error writing to file!\n");
	else
		printf("Wrote output file 'image.raw' (%d bytes)\n", buffer_size);
			
	fclose(file);
	
	//clean up
	if (-1 == vcap_destroy_cameras(cameras, num_cameras)) {
		printf("Error: %s\n", vcap_error());
		return -1;
	}
	
	free(raw_buffer);
	
	return 0;
}

sailfish009/vcap

Vcap

Introduction

Building and Installation

Example

License