Mass Converting .ppm into mp4

I'm wondering if there's a way that I can use the CLI to mass convert a bunch of .ppm flipnote video files into mp4 files, while also retaining the same filename.

Start by inspecting the command-line conversion flow in this Node.js tool and how it handles PPM input and output filenames. Determine whether batch input and same-name MP4 output are already supported; done means the CLI converts multiple .ppm files to corresponding .mp4 files while retaining their base filenames.

Written by the indexing model from the issue text.