<./sound_in.wav> comes from https://github.com/deltachat/deltachat-android/tree/a7b86dd59a8f5acfdf5d3da82aaca26651928fd9/src/main/res/raw.

<./ringtone-afro-nigeria-short.opus> comes from
<https://git.jami.net/savoirfairelinux/jami-client-android/-/blob/111ccc5116ec2f1fe5955b19f1fa3c111271ff83/jami-android/app/src/main/assets/ringtones/1%20AfroNigeria.opus>.
It's a shortened version of it. License- and attribution-wise
see the file's metadata. Artist: Loïc Bogino. Creative Commons.
