ffmpeg is not iFFMpeg, the "i" make a big difference.
In fact, iFFMpeg is just a software charge the user to provide GUI (basic functions) for FFMpeg. For complicated stuff, still need to enter command in iFFMpeg to finish the job. And I don't think iFFMpeg has GUI for remux.
Edit: I am sorry for my over react, may be you just want to introduce FFMpeg to him, but not misread iFFMpeg as FFMpeg. Sorry about that.
This is the opposite of what
@h9826790 has stated. But either way, what's the difference between using iFFMpeg vs Handbrake? Handbrake is free, where as iFFMpeg looks like is a paid software.
And NO, no need to transcode or encode. You can indeed remux it via a free software called Subler (GUI).
Or FFMpeg (the free one), in terminal with command
ffmpeg -i source.mkv -c copy destination.mp4
Do not transcode the video just for changing container unless really required, remux is hundred times faster, and no lost.
[doublepost=1501093097][/doublepost]
You need to transcode. I use iFFMpeg for all my transcoding. The only container I know you can change to mp4 is m4v. Changing the extension has worked fine for me.
Change container is NOT rename.
Yes you can rename M4V into MP4 and still work properly. But you can also change container for a video (e.g. from MKV to MP4) and the video still valid for players. This process called remux, it's a bit more complicated than rename. But no encoding involve, so hundred times faster than transcode.
[doublepost=1501095769][/doublepost]I just made a video to shows how to perform this remux with FFMpeg in command line.
As you can see in the video, it's super fast. Even the original video is only 13s long, normal transcoding still require few seconds to process. And remux actually finish within half second. And in the video, it actually shows the speed is 365x. That's more than 20000 FPS, way faster than normal transcoding.
After remux, the new video is in MP4 format, and it's playable with the exact same content as the original video, same bitrate, same resolution, same codec, etc.