nvcamerasrc exposure time vs sensitivity

A few questions regarding nvcamerasrc and exposure time & sensitivity.

  • What unit is the exposure-time in?
  • Is there a way to cap the exposure-time so that it is automatic but does not become greater than a certain value?
  • I do not see any control for sensor sensitivity (ISO). Is that always automatic and not controllable?
  • Does the AE-region potentially affect sensitivity as well or is it purely tweaking the exposure time?

Thank you!

Hi logidelic,

nvcamerasrc is deprecated from L4T 31.1 which though supports only Xavier.
But following 32.2, also supporting TX2, has only nvarguscamerasrc.
So your development is better based on nvarguscamerasrc.

hello logidelic,

several Q&As as below,

  1. please refer to Sensor Driver Programming Guide for the [Control Handlers] session,
    the unit of the exposure-time controls is seconds.

  2. there are exposure-time boundaries definition, you should also check sensor device tree properties settings.
    for example,

mode0 {/*mode IMX185_MODE_1920X1080_CROP_30FPS*/
                                        min_exp_time = "30";
                                        max_exp_time = "660000";
  1. normally, sensor sensitivity (ISO) is controlled by sensor gains. there are two types of sensor gain, analog-gain and digital-gain.
    since digital-gain always introduce lots of noise, we usually waive it for better image quality.
    you could also refer to imx185_set_gain() function in the sensor driver to have more details.

  2. AE region will affect sensitivity, since CameraCore library calculate the suitable AE settings and these new settings will also apply to corresponding frames.