Codec in the GOPRO?

Hi! I'm a french student, and I'm working on the GOPRO as a projet for my study. GOPRO format is MPEG4, and I'd like to know if there is an electronic circuit into the camera allowing the coding H264 ? Or is the coding done by a software ? In french, we call it a "codec".

I hope that my question is enough clear, thanks in advance.

Megan