I videod a jazz singer at an outdoor concert, where there is a lot of talking in the audience going on. I found that by using the multiband compressor by lowering the high end, I could reduce this noticeably, but I wonder how I might go further using compression, noise gates etc. Any suggested settings?
I would avoid using a compressor, in fact it could actually make the audience noise worse because compressors tend to boost the quiet parts and curb the loud parts of an audio waveform. If the performance volume is loud compared to the sound level of the audience you'll have the best results using a gate but you'll have to play with the settings to get it to sound natural.
You might also try a parametric equalizer or 'notch' filter, here again you may have to play around to get the right settings but perhaps you'll find the crowd noise is most prevalent in a certain frequency range and you can dial down that portion of the audio spectrum. Of course you'll lose the performance content in that portion of the spectrum too but your goal is to strike a balance between taking out the parts you don't want and leaving in the parts you do.
One trick I use when I'm looking (listening) for which frequency that I want to lower is to actually boost the frequency at arbitrary point then move that frequency "center" around until I hear the noise the loudest, which tells me that is my 'notch' point, then lower the gain.
It's easier than I've made it sound, it just takes some playing around to get it to sound "right" and take care that you don't make the fix worse than the problem, if that makes sense.