V4L2 라이브러리(해상도, 캡처설정) 사용 코드 요약

//이번 문서는 개인저장용이므로 다소 보기 어려울수도있으니 양해바랍니다.

void CameraInstance::initResolution(int width, int height, int fps)

{

    v4l2_format fmt;

    CLEAR(fmt); //memset(&fmt, 0, sizeof(fmt));

    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    fmt.fmt.pix.width  = width;

    fmt.fmt.pix.height = height;

    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;        // V4L2_PIX_FMT_MJPEG;  // V4L2_PIX_FMT_YUYV;

    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;            // V4L2_FIELD_INTERLACED;

    this->xioctl(d->mDeviceHandle, VIDIOC_S_FMT, &fmt);

}

bool CameraInstance::initMMAP(int handle, void*& mmapBuffer)

{

    v4l2_requestbuffers req;

    CLEAR(req);

    req.count = 1;

    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    req.memory = V4L2_MEMORY_MMAP;

    if (-1 == this->xioctl(handle, VIDIOC_REQBUFS, &req))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : Requesting Buffer"), CLogWriter::LOG_TYPE_RELEASE);

        return false;

    }

    v4l2_buffer buf ;

    CLEAR(buf);

    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    buf.memory = V4L2_MEMORY_MMAP;

    buf.index = 0;

    if(-1 == this->xioctl(handle, VIDIOC_QUERYBUF, &buf))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : Quering Buffer"), CLogWriter::LOG_TYPE_RELEASE);

        return false;

    }

    mmapBuffer = mmap (NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, handle, buf.m.offset);

    //   printf("Length: %d\nAddress: %p\n", buf.length, buffer);

    //   printf("Image Length: %d\n", buf.bytesused);

    return true;

}

cv::Mat CameraInstance::captureQueryImage(int handle, void* mmapBuffer, int width, int height)

{

    v4l2_buffer buf;

    CLEAR(buf);

    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    buf.memory = V4L2_MEMORY_MMAP;

    buf.index = 0;

    if(-1 == this->xioctl(handle, VIDIOC_QBUF, &buf))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : CaptureQuery Buffer"), CLogWriter::LOG_TYPE_RELEASE);

        return cv::Mat();

    }

    if(-1 == this->xioctl(handle, VIDIOC_STREAMON, &buf.type))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : Capture Error"), CLogWriter::LOG_TYPE_RELEASE);

        return cv::Mat();

    }

    fd_set fds;

    FD_ZERO(&fds);

    FD_SET(handle, &fds);

    timeval tv;

    CLEAR(tv);

    tv.tv_sec = 2;

    int r = select(handle+1, &fds, NULL, NULL, &tv);

    if(-1 == r)

    {

        CLogWriter::printLog(QString("[CameraInstance::] : Waiting for Frame"), CLogWriter::LOG_TYPE_RELEASE);

        return cv::Mat();

    }

    if(-1 == this->xioctl(handle, VIDIOC_DQBUF, &buf))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : Retrieving Frame"), CLogWriter::LOG_TYPE_RELEASE);

        return cv::Mat();

    }

    cv::Mat matrix(height, width, CV_8UC3, (uchar*)mmapBuffer);

    cv::Mat decodedMatrix = cv::imdecode(matrix, CV_LOAD_IMAGE_UNCHANGED );

    return decodedMatrix;

}

int CameraInstance::open_device(const char* dev_name, int& fd)

{

    struct stat st;

    if(-1 == stat(dev_name, &st))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : %1 : %2, %3").arg(dev_name)

                             .arg(QString::number(errno).arg(strerror(errno))), CLogWriter::LOG_TYPE_RELEASE);

        return ERROR_LOCAL;

    }

    if(!S_ISCHR(st.st_mode))

    {

        CLogWriter::printLog(QString("[CameraInstance::] : %1 is not a valid device").arg(dev_name), CLogWriter::LOG_TYPE_RELEASE);

        return ERROR_LOCAL;

    }

    fd = open(dev_name, O_RDWR | O_NONBLOCK, 0);

    if(-1 == fd)

    {

        CLogWriter::printLog(QString("[CameraInstance::] : Cannot open '%1' : %2 %3").arg(dev_name)

                             .arg(QString::number(errno)).arg(strerror(errno)), CLogWriter::LOG_TYPE_RELEASE);

        if(EACCES == errno)

        {

            CLogWriter::printLog(QString("[CameraInstance::] : Insufficient permissions on '%1' : %2 %3").arg(dev_name)

                                 .arg(QString::number(errno)).arg(strerror(errno)), CLogWriter::LOG_TYPE_RELEASE);

        }

        return ERROR_LOCAL;

    }

    return SUCCESS_LOCAL;

}

int CameraInstance::errnoexit(const char *s)

{

    CLogWriter::printLog(QString("[CameraInstance::] : [%1] : error %2, %3").arg(s).arg(QString::number(errno)).arg(strerror(errno)), CLogWriter::LOG_TYPE_RELEASE);

    return ERROR_LOCAL;

}

int CameraInstance::xioctl(int fd, int request, void *arg)

{

    int r;

    do r = ioctl (fd, request, arg);

    while (-1 == r && EINTR == errno);

    return r;

}

int CameraInstance::xioctl(int fd, int request, v4l2_queryctrl *arg)

{

    int r;

    do {

        r = ioctl(fd, request, arg);

    } while(-1 == r && EINTR == errno);

    return r;

}

int CameraInstance::cioctl(int fd, int request, v4l2_control *arg)

{

    int r;

    do {

        r = ioctl(fd, request, arg);

    } while(-1 == r && EINTR == errno);

    return r;

}