VOutputV4L2 C++ lib. Simple interface to write video frame to V4L2 output devices
VOutputV4L2 C++ library version 1.0.1 provides interface to write video frame to V4L2 video devices in Linux OS.
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Overview
VOutputV4L2 C++ library provides interface to write video frame to V4L2 video devices in Linux OS. An example of a video device is v4l2loopback device (virtual video devices). Normal (v4l2) applications will read these devices as if they were ordinary video devices, but the video will not be read from e.g. a capture card but instead it is generated by user's application. Using the library user's application can be as video source for third-party processes. The library provides simple interface. It depends on open source Frame library (describes video frame structure and pixel formats) and open source Logger library (provides method to write logs). The library supports C++17 standard and works only on Linux with V4L2 API support.
Simple interface
class VOutputV4L2
{
public:
/// Get library version.
static std::string getVersion();
/// Open device.
bool open(std::string device);
/// Write video frame to device.
bool write(Frame& frame);
/// Set log level.
void setLogLevel(cr::utils::PrintFlag flag);
/// Close device.
void close(void);
};
Simple example
#include <iostream>
#include "VOutputV4L2.h"
int main(void)
{
// Open video device.
cr::video::VOutputV4L2 videoOutput;
if(!videoOutput.open("/dev/video4"))
return -1;
// Create YUV frame with certain resolution.
cr::video::Frame frame(640, 480, cr::video::Fourcc::YUV24);
// Main loop.
uint8_t value = 0;
while (true)
{
// Fill image by color.
memset(frame.data, value++, frame.size);
// Write frame to device.
if(!videoOutput.write(frame))
std::cerr << "Cant' write frame" << std::endl;
// 33ms delay for 30 fps stream
std::this_thread::sleep_for(std::chrono::milliseconds(33));
}
return 1;
}
