Personally I think that Video Editing & Production fits naturally here and Audio has been a part of “Movies” since before the word video came into place. (I know some still hanker after the purity of monochrome and don’t think sound should come into the picture).
For FOSS video editing the possibly the ultimate package is, to me, FFMPEG I am sure that it is the back end of many of the packages already mentioned but of course with great power and flexibility comes a horrible user interface and an even more horrible set of documentation. Another very powerful but not for the faint of heart set of tools is contained in the incredible OpenCV library.
Another very powerful video & photo manipulation & editing tool with possibly a slightly less horrible UI is MoviePy which behind the scenes uses several other python libraries along with FFMPEG, ImageMagick & optionally OpenCV. On the audio side I often turn to Audacity which has great tools for removing background noise from video sound tracks, (once you have separated them from the video).