More Granular File Optimization

I would like more granular control over optimization.
E.g., if the original file was a movie in h.264 1080p with 5.1 AC3 audio, I would like the option to “pass thru” the video part of the file and perhaps down mix the audio to 2.0 AAC plus keep the original 5.1 AC3 audio component.
The result would mean faster conversions, preserving the original audio + video and adding a 2 channel audio file for direct play in web player and only a small increase in size of the original file, (which could be trashed, since all the original stuff has only been added to).

What seems to happen for me is the optimization preset “original” converts the video file and the audio file and often the resulting file is significantly larger than the original!

There’s already a bunch of suggestions addressing this from different angles. I suggest you comment/vote in those in order to avoid distracting/dispersing votes.

2022 clean-up: considered to be a duplicate