I generally just make minor adjustments to brightness, contrast, and gamma to make my home videos look better. Nothing fancy. I just have grown accustomed to doing it without an RGB conversion. And in AVIsynth, I just look at the Y-channel to avoid clipping. On the histogram, you can see Y-values that go outside the broadcast safe range. And you can see that pretty well in Shotcut also which I appreciate. In contrast, with Kdenlive, it converts to RGB then plots the histogram so it clips the parts that are outside the broadcast safe range. And it is plain as day when you compare histograms in different tools.
I usually scroll through a clip and identify the high/low points, shift the Y channel a bit (with the Levels filter in AVISynth) to get it in the broadcast safe range as much as possible, then apply a limiter. You get less clipping that way. And for really dark clips, I usually adjust gamma because I get a nicer result that doesn’t lighten the really dark areas as much. But I’m just eyeballing that.
I never do any serious color grading with RGB. That would be too much work for home videos. The only adjustment I’ve ever made to the UV channels is white balancing where I shift them a bit. AVISynth has a histogram for the U and V channels also, and there’s a function that auto-centers them. But it has to be way-off for me to do even that. On that note, I noticed the White Balance filter in Shotcut converts to RGB.
FFmpeg/libav has an eq filter that looks like it can adjust brightness/contrast/gamma without converting to RGB. But it is difficult to use without a histogram and without seeing the video clip. It’s much easier having it in an NLE! Granted, I can keep using AVISynth, it’s just a pain. It only runs on Windows and I’m trying to move to Linux. VapourSynth seems to be taking its place and has many of the same functions but it doesn’t handle audio which is very limiting. And neither AVISynth nor VapourSynth offer proper editors with timelines. And I’ve decided I need that in my life. Even if it means an RGB conversion! :). I’ve just read over and over how lossy it is so I’ve always avoided it.