Below are some tools to help with audio based Mid Side processing. The tools you will need will depend on the kind of DAW you are using. The below tools are free to use.
Some further resources to help you understand M/S processing.
- How does Mid-Sides encoding/decoding actually work? (SOS, April 2017)
- Creative M/S Techniques 1 (SOS, Nov 2019)
- Creative M/S Techniques 2 (SOS, Nov 2019)
- How to widen a mix using mid/side processing (MusicRadar, Feb 2015)