Re-encoding a video file to reduce the audio volume by 50 per cent.

© copyright 14.Jul.2009 by Paul Bradley filed under Video

I had recorded a screencast for work today, and when the video was finished it turned out that the sound volume was way to high, so much so that even reducing the volume control to it's lowest setting meant the video was still too loud.

Not wanting to record the whole video again with new sound input levels, I needed to find a way to re-encode the original video with a new sound level. This is where ffmpeg helped. FFmpeg is a complete cross-platform solution to record, convert and stream audio and video files. It is available for Windows and Linux, and is a command line utility.

One of the command line options is -vol which allows you to increase or decrease the volume from an input file while encoding to a new output file. A setting of 256 equals normal volume, so in my case to reduce the volume by 50 per cent I needed to supply a -vol parameter of 128.

So the full command line would be :-

ffmpeg -i original.avi -vol 128 newfile.avi

Where original.avi is the original video file which was too loud, and the new quieter file newfile.avi is created.


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Paul Bradley

About the Author
Paul Bradley is a VB.NET software developer living and working in Cumbria. He has over 20 years programming experience. He also produces e-learning videos at Linux by Example

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