codec for playing MP4s?

[gnip gnop]

I downloaded video files as MP4's and have not been able to play them.
I tried Windows Media Player, VLC and SMPLAYER. I got an error message indicating that codecs might be missing.
Does anyone know what codecs are needed (and where to get them), or how to play these files?
Thank you!

[famba]

I also have this question and am astounded that this remains unanswered. Why has Amcrest STILL NOT released a codec that can be used in VLC and then not require conversion by the buggy and difficult to use Smart Play?

[Melvin]

Hello famba ,

The MP4 files can be played in VLC or Windows media player without needing any codecs.