I'm looking for a loudness or volume control plug-in or app. Rendering versus real-time is fine. I am already familiar with VideoToolShed's Loudness Change and iZotope's RX Loudness Control.
Typically the ones I'm familiar with will normalize a clip to a target volume based on the highest peak within that clip. This will bring the level of the entire clip up or down, but relative differences within a clip don't change. I also don't want a compressor, since those often sound too harsh. What I want is something more akin to Waves VocalRider.
In other words, it will bring the peak levels down to a target setting, but also raise the quieter sections - all WITHIN a clip, not between clips. The result would be like riding levels, but without the need for keyframing the volume within a clip.