In this post, I am going to explain how to merge a Video with an External Audio in simple steps. First you will need a software called Avidemux which of size 11MB. Now you might be asking a question that "I have format factory, why should I need this software". Because format factory may show an error called Install codecs while processing 720p or 1080p videos and its a little bit slower in processing videos. This software which am going to explain is light weight and faster in processing videos. Before going to merge the video and audio you should first edit the video so that the audio matches the video. You might use Softwares like Audacity , sound forge, Format factory to edit audio. In my point of view Audacity is the best and easy to edit Audio. Download Avidemux here Just follow the steps to Merge audio and video. Open the Avidemux software. Go to File -> Open and select the video file. If you selected a High defintion video , It will pr...