The only safe way to obtain this file is by installing the from its verified developer:
If you’ve landed on this page, you’ve probably encountered a frustrating error message while trying to launch a video game or a multimedia application. The pop-up might say: codex64.dll file download
GOG games, in particular, are DRM-free—no cracks needed. And they often go on sale for just a few dollars. The only safe way to obtain this file
DLL download sites are a breeding ground for malware. Hackers know that users searching for codex64.dll are likely trying to run software they downloaded from the internet (often illegally). They inject malicious code into these DLL files. When you download and run that file, you could be installing: you could be installing: