Increase Volume of an MKV Video from Linux Terminal

Question

I've got a large amount of .MKV video files which seem to all play at a very low volume - I end up having to turn the TV up all the way to hear them, which is really irritating when I switch to another channel and wake the dead because it's so loud.

What I'm looking for is a command-line method to increase the volume (so I can run it on all of them quickly) that would hopefully work regardless of the audio codec in use in the particular file. (I don't mind hard-coding the output audio though).

For reference, I'm using Ubuntu 9.04 on my server, and the files are being played back with Boxee on a Mac Mini, but the volume problem is the same on Windows too.

Since normalizing is often increasing the volume, check out this post; I use `ffmpeg-normalize` all the time, and it's easy to download with `pip`; it takes the guesswork out of using ffmpeg manually on the CLI: https://superuser.com/questions/323119/how-can-i-normalize-audio-using-ffmpeg — Life5ign, Apr 12 '23 at 05:18

score 28 · Answer 1 · edited Nov 27 '12 at 22:47

28

It isn't very well documented, but FFmpeg has a -vol switch which will allow you to increase volume output.

Example:

ffmpeg -i vid.mkv -vol 512 -vcodec copy output.mkv

Some things to take note of:

the -vol switch uses "byte percent", so you can't just specify a 200% volume increase, 100% = 256 so specifying 256 would leave the volume as is, 512 would double it and so on.

edited Nov 27 '12 at 22:47

markostamcar

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answered Aug 28 '09 at 06:49

John T

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Trying to test this out... looks like I need to re-compile ffmpeg from source to use matroska. Will report back! – The How-To Geek Aug 29 '09 at 04:52
I'll cross my fingers :) – John T Aug 29 '09 at 05:11
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Best solution ever and in 2018, it works out-of-the-box! – Olivier Pons Apr 18 '18 at 19:40
Is there also a way to normalize the volume? – white_gecko Aug 03 '18 at 15:52
For normalization this should be the right place to look: https://superuser.com/questions/323119/how-can-i-normalize-audio-using-ffmpeg – white_gecko Aug 06 '18 at 12:24
`-vol has been deprecated. Use the volume audio filter instead.` – Eray Erdin May 25 '21 at 10:24

Elder Geek · Answer 2 · 2021-02-03T19:56:16.073

The -vol switch is deprecated I've found this method to be useful currently:

ffmpeg -i input.mkv -vcodec copy -filter:a "volume=5.000000" output.louder.mkv

Adjust the number after volume= to suit your needs.

You can also use decibel measures. To increase the volume by 15dB: ffmpeg -i input.mkv -vcodec copy -filter:a "volume=15dB" output.louder.mkv

The -vcodec copy simply copies the video as is and -filter:a tells ffmpeg to filter the audio. Note that -vcodec can be shortened to -c:v

Sources:

https://trac.ffmpeg.org/wiki/AudioVolume

Testing.

Increase Volume of an MKV Video from Linux Terminal

2 Answers2