Mic problem

My iPhone 4 doesn't record any audio when I record videos, nor does it record any audio when using video apps like vine and snapchat.

I am still able to record voice memos, which seems strange. I have no problems making phone calls.

**Just to get the obvious out of the way**

- no the phone is not under warranty.

- please do not suggest that I take it to a mac store, I am aware of this option, I am looking for alternative solutions.

- It's definately a 4, it's not a 4S