GUIDE: MP3Gain, Losslessly adjusting the volume of your MP3s

Mokubai · 02-20-07, 08:55 AM

The Problem

For those of you, like me, who use your Axim as an MP3 player you may have noticed that you are constantly adjusting the volume to compensate for the fact that all your music seems to be recorded at different volumes. This can be frustrating when you have a large collection of music all at wildly different volumes playing on random or shuffle.

The solution

Enter MP3Gain. What MP3Gain does is to adjust (in a lossless and recoverable manner) a volume gain control that is integral to every frame of music in an MP3 file. The changes it does are stored in an APEv2 tag (which shouldn't interfere with an mp3 player) so that the original volume levels can be restored if you wish, thus reverting the file back to the way it was before you made the adjustment.

The benefits of the program are two-fold. Firstly it reduces the volume levels to a point that while it is not so low as to make the files un-listenable, it is low enough that a player that fully adheres to the mp3 standard will not "clip" the audio and possibly produce clicks or pops. Secondly, and this is the major benefit, all mp3s can be given a very similar volume. The accuracy of the volume control is "only" 1.5dB which is due to the lossless way that the volume is controlled, but in general this is more than accurate enough. The volume level detection is also not done purely by peak volume, it is done using a method developed by the author of ReplayGain (http://www.replaygain.org/) that detects the peak "audible" volume that the listener is likely to hear which means that files that have a high volume noise that is relatively inaudible due to frequency does not play as much of a role in volume correction.

Get MP3Gain from http://mp3gain.sourceforge.net/download.php

I have attached a four small images showing MP3Gain and its usage.

The advice ;)

In a nutshell all you need to do is to add a directory or collection of mp3s using the program, analyse them and then apply gain. The analysis can take some time, especially with a large collection of mp3s, but only has to be done once. You never have to analyse again even when re-adjusting the gain.

I would recommend using the Album Analysis, available by the drop down arrow beside the Track Analysis button, so that it calculates the real overall gain required for an album if you later want the volumes to be consistent for track changes within an album as you get when tracks drift into each other. Then if you intend to listen to the tracks randomly select "Track Gain" and all of the tracks will be adjusted as closely as possible to the "Sweet Volume" of 89.0dB, or as closely as is possible by changing the volume in 1.5dB increments. With Track Gain if you have done an Album Analysis it will also record the required gain needed to bring the tracks back to their original relative volumes while still keeping the volume close to the target volume. One benefit of the Album Gain feature is that when doing a large collection it only considers tracks that are in the same directory to be the same album so if you have a directory structure like Artist\Album\Track then only tracks within that album directory will be used to calculate and adjust Album Gain.

Even after doing both a Track Gain and then an Album Gain you can still restore the original volumes of each track by selecting the track you wish to restore (or by using Ctrl+A in the track window) right clicking and selecting "Undo Gain Changes" as can be seen in the fourth image I've attached. All track volumes will simply be returned to original values.

I would also recommend doing this on a hard drive, as it will be a lot faster. While it does work on flash media I found out to my own detriment that it takes a lot longer, and probably causes a lot more writes to the media.

This is my first guide and I did check that no-one has released something similar, I just wanted to give something back to the community, so be gentle ;).

If you find it useful or if there are any corrections or additions I should make then please let me know.

Once again, get MP3Gain fromhttp://mp3gain.sourceforge.net/download.php

02-20-07, 02:19 PM

Better to use a player that handles it rather than go through and adulterate all your files. For mp3, Lame (current ones) do a replay-gain automatically (whether it does it well or not...), and itunes lets you set the RVA manually for mp3 files (a little louder, a little less loud, ...), and the way I prefer is to use a plain old id3 comment with track_gain=+3. The only player I know that handles all these modes is Zircon.

http://zircon.40th.com/

mp3gain would do for players that don't handle external loudness specs, but what it does is to go though each file and alter - what it hopes - the global gain for a frame (1000s of frames per file). If it gets out of sync, the file is trashed. Maybe it can undo it, maybe not, but it still has to do that to every file. Players like Zircon do this as it plays (in memory), not altering the file at all.

Mokubai · 02-20-07, 04:13 PM

Well, even if I wanted to I cannot look at Zircon, your lovely "Email me to be one of the privileged few" page comes up.

While I respect that "adulterating" mp3s is not optimum, it is better than nothing if you need the files to have the same volume with no recaculation done "on the fly". I've personally only done it on files I've copied to my pda and in the more than 400 of them I have seen absolutely none of this corruption that you talk about. Do you have any proof whatsoever (aside from your shameless self-advertising) that it does corrupt files?

Now, granted that I've not listened to *every* file but with the player on shuffle for every file I play I have an ever decreasing pool of possible corrupted files and thus an exponentially decreasing probability that I will have one. I know that any program that modifies file contents for you has a chance of corrupting files but the build I used is marked as "Stable" and if it had lots of problems, as you seem to think it should, then it would not have been marked as such. People have tested and proven it stable.

I have tested it and, from my experience, it seems trustworthy. I wouldn't have suggested it to others without testing it on my own data first.

Pocketbrain · 02-20-07, 07:19 PM

Nice, I would like to use this for music files on my PDA.

bully79 · 02-22-07, 06:39 AM

ive been using mp3gain for over a year now and i think its excellant!

02-28-07, 05:25 AM

How many id3 taggers understand "mp3gain"? Probably none. I doubt wmp does (what most will be using to tag), and I doubt iTunes does (what the rest will). Once you change a tag, any tag, it's a pretty good bet the mp3gain "save" value is gone for good (tags are often rewritten in whole on any change). Now there's no way to undo it, and it's another fine mess you got yourself into.

mp3gain is not a good way to do this. It is A way, but not a good one. And that's not even getting into how valid this guy's "mp3gain" algorithm is (when it is, when not, ...).