What is the algorithm for storing and recording audio messages, using WhatsApp as an example?

Question

Android

Hello!
Tell me how the scheme for recording and storing audio messages is implemented, for example, as in WhatsApp?
I understand correctly that the algorithm is something like this:
1. Recording a message on the phone using the Android SDK, Swift, etc.
2. Converting audio to the desired format (if so, which one?).
3. The recorded file is sent to the server. A local copy remains with the person who recorded the audio.
4. The recorded audio file is loaded at the recipient.
Thank you!

Answer 1

I think yes, I would. The same algorithm is suitable for sending any other type of files, such as photos or videos.