Friday, May 15, 2009

How to normalize or increase/decrease audio volume of a video

Often we come across videos that has either a very low or a very high audio volume that forces us to adjust the volume level in our speakers or media player. Sometimes the audio is so faint that turning up the audio volume knob only amplifies the background noise making the actual audio inaudible. Fortunately, there is a fix available.

To rectify such video files, we have to adjust the audio level or in other words, normalize the audio. Earlier I had shown you how to normalize MP3 files. This time we will normalize a video file.

The software we will require is Virtualdub, a free open source video editor. Remember that this method will work only with AVI files (i.e. MPEG4 encoded). If you have an MPEG file you will need to convert it to AVI first.

Open Virtualdub and load the video into the editor.

From the Video menu, select "Direct Stream Copy".

 virtualdub1  

From the Audio menu, select "Full Processing Mode".

virtualdub2

From the Audio menu click on “Volume”, check the box "Adjust volume of audio channels" and then adjust the volume level using the slider.

virtualdub3

Preview the volume level by playing the output video file. If you are not satisfied, go back to the previous step to readjust the volume.

virtualdub4

Finally, save the file as AVI.

9 comments:

  1. Right on!
    I use virtualdub when I want to convert the video/audio for playing on a portable device or my divx dvd player.
    However, if I'm just playing files on my PC then 'ffdshow audio decoder' (installed with the klite mega codec pack) has an inbuilt volume normalizer (is that even a word? :) ) that works perfectly.

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  2. Thank you for the tutorial.... both of you

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  3. This is a fantastic post. You saved me from a night of hell. I was looking for this exact information. Thank you so much. I am trying to start some video tutorials for my site at Plain Tech Talk and with the cheapo screen recorder I am using I just can't seem to get the volume to come out right no mater what I try. This did it.

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  4. Thank you so much!! You saved my video from the trash can! The avi was so quiet, but now it's perfectly fine. You did a great job explaining this. I had spent hours looking for the answer. It was pretty easy to fix w/your advice! :D

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  5. How about equalizing the volume? Isn't that what Normalizing really is? I have vids where one person is less audible and the other is very loud (mic positioning is odd) and I want to put them at equal levels - I thought THAT is what normalizing is - how do I do that in Vdub?

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  6. @Greg: No, normalization does not do that. It just applies a uniform gain through the track, which means, low volume sounds will have a higher volume while high volume sounds will have an even higher volume. :(

    The kind of processing you are looking for would require analyzing volume of each individual frequency and dynamically adjusting it to the required volume. This can be done only in the studio where each track is recorded separately.

    It is impossible, AFAIK, to extract the voice frequencies of one person from a multitude of frequencies generated by different persons and sources.

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  7. Great post, I can do it with mpeg1 video file as long as I choose video/full process mode. the target avi file size however will be really big (some GB for some minutes video). But you can easily convert it to mpeg1 again with TMPGEnc.
    Thank for useful post

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  8. GREAT post
    You only forgot one little think to make it perfect.
    The new generated audio needs an compression. Otherwise the file will be MUCH too big.
    Menu: Audio|Compression

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  9. well intersting tutorial. but, it's a manual methode and if for only 1 video it won't be a matter. for batch process try XMedia Recode, a freeware. you can adjust all your video at the same volume, exactly.

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