Blacking out a scene for a blu-ray file without converting

Hey I'm trying to have some blu-rays ripped by makemkv by way of mkvmerge and solveigmm avi + mkv trimmer; however, I need to find a way to black out some scenes while keeping the audio playing (basically cutting out nude scenes).

Does anyone know how to do this with the software I listed or by any other software that won't convert the video/audio so I don't lose audio/video quality.

Thanks in advance for your input.