Gstreamer v4l2src usb camera exposure control

[jwna1885]

Dear all,

I want to control exposure of usb camera using v4l2src in gstreamer pipeline.
I’ve seen a comments that it is not supported in 2018, but it would be included for future version.
So, I want to ask if I can control exposure of usb camera now using gstreamer pipeline with v4l2src.

Thank you in advance.

[JerryChang]

hello jwna1885,

that’s not supported since USB practically control exposure internally, and output YUV frames to user-space.
may I know what’s your actual use-case. how about toggle the brightness settings?

[jwna1885]

I just wanted to set exposure time manually since sometimes it is too bright.
Can I toggle the brightness settings in USB camera?
If I can, how can I do it? I’m using gstreamer pipeline as below.

std::sprintf(gstreamer_api_str, "v4l2src device=/dev/video0 "
                "! image/jpeg,width=%d,height=%d,framerate=%d/1 "
                "! nvv4l2decoder mjpeg=1 "
                "! nvvidconv "
                "! video/x-raw(memory:NVMM),format=NV12 "
                "! nvvidconv flip-method=0 "
                "! video/x-raw, format=(string)BGRx " 
                "! videoconvert "
                "! appsink", config.stream_w, config.stream_h, config.frame_rate);

[JerryChang]

hello jwna1885,

please check the Element Properties for v4l2src,
for example,

  brightness          : Picture brightness, or more precisely, the black level
                        flags: readable, writable, controllable
                        Integer. Range: -2147483648 - 2147483647 Default: 0