Vide Editing ... CUT / CONVERT / INCREASE VOLUME OF MPEG/MP4 VIDEOS USING FFMPEG OPEN SOURCE TOOL

Download ffmpeg from https://www.ffmpeg.org/download.html for your OS

Cut/Extract portion of video between starting time stamp 00:03:55 and till 00:04:44 
ffmpeg -i D:\invideo.mp4 -ss 00:03:55 -to 00:04:44 -async 1 -strict -2 outvideo.mp4


If the -ss [Start time] is far from beginning of the video file, then
it takes long time before it starts generating the output file.
DO NOT kill the command thinking it's not running.

Convert DVD vob file to mp4 
ffmpeg -i D:\invideo.VOB -ac 2 -ab 128k -vcodec libx264  -threads 0 outvideo.mp4

Increase/Decrease/Mute volume in mp4 video
Increase volume by 10dB (decibel)
d:\ffmpeg\bin\ffmpeg -i invideo.mp4 -vcodec copy -af "volume=10dB" outvideo.mp4

Decrease volume by 10dB (decibel)
d:\ffmpeg\bin\ffmpeg -i invideo.mp4 -vcodec copy -af "volume=-10dB" outvideo.mp4

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Other softwares
Linux - YouTube Downloader;
from Menu  --- Software Manager search for 'You Tube Downloader' youtube-dl will be installed

Linux - Video Editing GUI Tool -- ShotCut

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Installing ffmpeg in Mint Linux 17.x
https://mintguide.org/video/339-installing-ffmpeg-library-on-linux-mint-via-ppa.html

sudo add-apt-repository ppa:mc3man/trusty-media
sudo apt-get update
sudo apt-get install ffmpeg