Combining an audio file with a video file

Question

I have two files: one audio and one video (mp4).

I want to create from those two files, one video file that will contain both the audio and video output. The main issue is the synchronization between both of those recorded files. There's a man speaking, and the movement and sound need to line up.

I heard about the FFmpeg library for iOS but didn't found any good information about it.

Answer 1

As others have pointed out in the comments, you should use AVFoundation to merge audio and video into one file. This answer shows how to do it:

How to write a movie with video AND audio using AVAssetWriter