How to add still image to audio file to convert it into video? I am using QuickTime Player. From initial research it seems i would need QT Pro to do it. Is there a free opensource tool i can use for a simple task like this?

On opening the audio .m4a file in QT the Edit Tab options like copy paste etc are coming out to be disabled.
There are many open source video editing softwares that you can use to make a video from a still and a song.

These are some of the best open source video editing tools that you can use.


Blender
Kdenlive
Avidemux


Also here is a full tutorial to create video from still image and from audio file.