CODEWITHSUNDEEP
linuxresolutionvideo-capturev4l2
Elmi
Elmi

Reputation: 6203

Get v4l2 video devices maximum resolution

how can I just detect the maximum resolution a connected video device is able to provide?

I do not want to capture anything, just retrieve this information from v4l2.

Thanks!

Upvotes: 2

Views: 4603

Answers (1)

umläute
umläute

Reputation: 31284

use the VIDIOC_ENUM_FRAMESIZES ioctl:

    enum v4l2_buf_type type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    struct v4l2_fmtdesc fmt;
    struct v4l2_frmsizeenum frmsize;
    struct v4l2_frmivalenum frmival;

    fmt.index = 0;
    fmt.type = type;
    while (ioctl(fd, VIDIOC_ENUM_FMT, &fmt) >= 0) {
        frmsize.pixel_format = fmt.pixelformat;
        frmsize.index = 0;
        while (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &frmsize) >= 0) {
            if (frmsize.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
                printf("%dx%d\n", 
                                  frmsize.discrete.width,
                                  frmsize.discrete.height);
            } else if (frmsize.type == V4L2_FRMSIZE_TYPE_STEPWISE) {
                printf("%dx%d\n", 
                                  frmsize.stepwise.max_width,
                                  frmsize.stepwise.max_height);
            }
                frmsize.index++;
            }
            fmt.index++;
    }

afaik, VIDIOC_ENUM_FRAMESIZES was introduced in linux-2.6.29

Upvotes: 8

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