Legacy Audio Shortcode

I have recently redone a site that was originally created in 2011. Of course there were a few big development issues and one of them is the usage of an old audio shortcode:

[audio:https://localhost:8888/lusa/audio/1310seg02.mp3%5D

I have not seen any documentation of the native WordPress audio shortcode ever using a colon. I have also not been able to find a plugin that uses it in this way.

Does anyone know how I can get this shortcode functioning? I believe my options are.

Create a script that turns this audio shortcode into the newer format [audio src="https://localhost:8888/lusa/audio/1310seg02.mp3] https://codex.www.ads-software.com/Audio_Shortcode.
Find the plugin that originally made the shortcode this way.