CoreCodec went bankrupt around 2013. Their Android and iOS apps failed to compete with VLC and MX Player. However, the lives on in spirit. Later versions of KMPlayer and PotPlayer used similar low-level renderers.
If you are currently setting up a retro Nokia device, let me know: What are you trying to run CorePlayer on? coreplayer symbian s60 v5 1
CorePlayer is a popular media player software for Symbian-based smartphones, particularly those running on S60 v5.1. This review aims to provide an in-depth look at the features, performance, and usability of CorePlayer on Symbian S60 v5.1 devices. CoreCodec went bankrupt around 2013