There is 12dB on the camera screen. What do you mean?

Professional cameras have a switch called "gain" or "gain" switch. This switch is mainly turned on when the brightness of the shooting environment is poor, which plays the role of amplifying the video signal. Generally, the gain switch has three gears: high, medium and low. You can also set three gears more widely through the camera setting menu. For example, the "middle range" can be defined as 0dB or -3dB or 3dB, and the "high range" can also be defined as 9dB or 12dB or even 18dB.