Changing volume of digital files

[semloh]

Mark - or anyone else - can you please tell me how you can increase the volume of audiofiles. I have several that are so quiet (not from this forum) that I have to have my speaker volume up at maximum - which of course creates problems, eg. when there are automatic sounds or when I play another file recorded at normal volume.
Thanks! 

[fr8nks]

Most of the members that upload music have a sound editing program. These programs can remove clicks and pops from LPs or cut the applause at the end of a recording if you find that annoying. Another feature is the ability to normalize the recording level. Usually this means making the volume the level that it would be on a commercial recording. This is easy for these programs to do since the music is digitized and it is a simple matter to increase or decrease the sound level of the recording. It may take 30 seconds to normalize a 50 minute recording. I use Wave Corrector which does a fantastic job of removing clicks and pops without affecting the music. In other words it doesn't filter high or low frequencies or alter the sound of the recording. This program is easy to use. Other members use Audacity which I believe is a free download but I find awkward to use. Wave corrector costs about $45 for a lifetime license. I have been using it for 8 years and receive all upgrades for free. I have converted about 2500 LPs to CD with unbelievable results. Many of the LPs are of CD quality. I hope this helps.

[Mark Thomas]

You beat me to it! I'd add only a couple of cautionary points. Firstly remember that if you have a multi-track recording (four mp3s for a symphony perhaps), you need to increase the volume by the same amount for each track. Just "normalising" each track will increase the volume of each to 95% or whatever, whereas a quiet slow movement should only be increased to 70% of the maximum so that its volume relative to the other movements is maintained. The best ways to do this are either a)"test drive" the normalisation process for each track and note the % increase of each and then increase them all by the smallest amount using the amplify command or b) if that isn't possible, combine the tracks, normalise and them either leave them combined or split them up again. The difficulty always is that if you save as an mp3 or other compressed format then the final file will be marginally worse quality than the original. There are posts elsewhere here which explain why and how you might get around it.

[semloh]

fr8nks and Mark - thank you for that advice.   

I'll approach the task with renewed confidence!

[britishcomposer]

I use mp3gain:
http://mp3gain.sourceforge.net/
It's easy to use and offers two modes: track gain and album gain.
You drag-and-drop the relevant files into the window and choose 'album analysis' or 'track analysis'.
I use always 'album analysis'  because it increases the volume of each file in relation. (The problem Mark mentioned is avoided by this.)
You can add and take away volume as you like: the file quality is not diminished in any way.
And moreover: it's free! 

[semloh]

britishcomposer - thank you! I'll give that a try. 

[Mark Thomas]

Yes, mp3Gain looks like the sovereign remedy to me.  You'll increase the volume of any background noise commensurately, of course, but that'll happen under any normalisation process in any program.