3ivx was and australian based MPEG-4 codec created by 3ivx-Technologies from 2001 to 2012. In many cases this codec was just a just like any other MPEG-4 codec like DivX or Xvid. 3ivx was used as an MPEG-4 decoder on Windows Phone 8. 3ivx was not free and would cost 20$ for a full version.
by Noah The Windows Guy June 2, 2021