How to increase the volume in an MP4 file.
Monday, 18 September, 2023 - 05:09
We've all done it: when recording to a video camera without any level indicator, we've finished and found out that the volume is too quiet.
There are lots of online services that say they do this - but they come with tiny sample tests that have a watermark or a monthly subscription.
What if you have one, 20 minute or so, video you want to fix. It's surprisingly easy (but possibly a little daunting) for Linux users.
In a terminal
First, if you don't already have Midnight Commander installed, install it.
sudo apt install mc
Run mc
Navigate to the directory where you have put your quiet file.
[it is prudent to make a copy of that file and to work on the copy]
let's make your life easy: Copy this to a notepad file:
ffmpeg -i test1.mp4 -c:v copy -af "volume=2" test2.mp4
Now, for test1 substitute the name of the copy. Then for test 2 substitute the name of the new file you want created (or just leave test2.mp4 and that's the name of the file you'll get. The number 2 will increase the volume to 200% i.e. double the original.
Then copy your amended version and paste it (shift+insert) into the command line.
If you'd like to monitor progress, then quit out of Midnight Commander and you'll see full information of what's happening in the terminal.
Remember that in Linux directories and filenames are case sensitive.
If it's not what you want, change the volume value and the name of the output file and run it again.
Thanks to bertieb at https://superuser.com/users/46... for pointing us in the right direction.
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