1. Install Homebrew through the macOS Terminal:
   `/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"`
4. Install ffmpeg:
   `brew install ffmpeg`
6. Copy the `mov_to_mp4.sh` script into a folder containing one or more QuickTime files.
7. Change to the directory containing the script:
   `cd /path/to/mov_to_mp4.sh`
6. Run the script to batch convert all .mov files to .mp4. Results will be stored in a subfolder named "output".
   `sh mov_to_mp4.sh`

This will create visually lossless mp4 videos that will play in a modern version of QuickTime. If a truly pixel-perfect lossless file is desired, change `-crf 15` to `-crf 0`. The resulting file will not play in QuickTime, but this is useful for creating intermediate archival copies that can be converted to a new format in the future without degradation.