The camera is externally connected with audio output.

You can't connect it like this, just add an attenuator (consisting of several resistors).

The attenuator is made by connecting an 8 ohm 10W resistor between the output of the power amplifier and the ground (if the power amplifier is connected to a load, this resistor can be omitted), then connecting 8K and 8ohm resistors in series between the output of the power amplifier and the ground, and outputting signals to the camera microphone at the connection point of 8k and 8ohm resistors. In other words, eight, eight and eight resistors are connected in a ∏-shape, with the upper left corner connected to the output of the power amplifier and the upper right corner output. If the signal strength does not meet the requirements, you can change the size adjustment of 8K resistor.

Of course, if the power amplifier has line output or earphone monitoring output, it can also be used directly.