Combining Audio & Video with FFmpeg

Learn how to replace the audio of a movie file without any loss in quality, and also how to add a new audio track to a movie file. We show how to do all this using FFmpeg, a free cross-platform tool.
Links and full commands are provided after the chapter list below:
00:00 Intro
00:58 Recap of last session
01:29 Replacing an Audio Track
02:38 The FFmpeg command to replace a track
08:05 Adding an Audio Track
10:00 The FFmpeg command to add tracks
12:35 Closing words

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Listing of Commands executed within this video::
A short description precedes each command as a "#" comment

# Command to list info about a movie file. (Note: the "-i" is optional for ffprobe)

[Jakeeenator]

This was a great straight forward video! I record for a local rap night near me and I have to adjust the bass levels in post. So using this to remux the audio is great. Thanks again!

[mnii_]

Your videos on antiX are really good and useful, you really have helped me to get on the linux hype and so far its been good,
So thank you
But i do have have a question, my pc is not really bad 6gb of ram + i3 370m (not a potato), should i stick to antiX, or should you get another distro that might utilize the minimal hardware i have.
My usage for such distro is only to watch YT at 1080p or twitch streams at 720 60 fps without my pc crashing, or simple multitasking, and thanks

[ic_]

what if your output is different from the first input? does ffmpeg simply ignore the instructions to not reencode? or that wouldn't be reencoding?