This is a very common problem and stems from the fact that you need two different mixes - one for the PA and one for your camera. PA engineers are good at PA mixes but not often video programme mixes at the same time!

It sounds as though you have taken an aux out from the desk (soundboard) into the camera but the aux does not have a good mix on it.

The good news is that if you have heard great sound from your camera when people are speaking then you can't be doing too much wrong at your end. The difference between analogue and digital is not important here - the feed you are getting is wrong to start with.

I approach the audio differently - I create a good program mix to camera using the main mix bus on the desk and then make a PA mix using an aux buss. I do a sound check for the camera audio before the PA is even turned on - that way I can hear what is being recorded because there is no loud PA confusing my ears. When I am happy with the camera mix I will then mix the PA audio making sure I don't change the main mix buss audio.

Hope this helps somewhat - try and get the venue audio engineer to approach the mix this way and let him/her listen from your camera before the PA is switched on.

Any questions please ask.

Good luck.