I played an mp3 today thats volume seemed much lower than most of my other mp3s, so I opened it in mptrim and clicked the auto volume button and it showed a suggest increase of over 7db. My question is: Is it better to re-rip the song so the volume increase can be done in the wav file or will raising the volume after the fact in the mp3 yeild the same result? I believe I read that mp3 encoding works in part by removing parts of music that we can't hear, so I wasn't sure if that also meant that very low volumed parts of the original were removed in the mp3 that might have been encoded if the original wav file was at a higher volume.

Thanks,

Bob

I am not sure how mptrim works. Programs like MP3Gain can losslessly increase the volume. This means that it will increase the volume without re-encoding the mp3 file. Re-encoding the file means that a quality loss will occur. So, if mptrim applies the volume change in the same was that MP3Gain does then you don't have to worry about it. I think it is just easier to use an application like MP3Gain instead of messing with the WAV files especially since WAV doesn't hold any track ID information (unless you had another lossless format like FLAC).

Yeah! MP3Gain is wonderful for this. I use it whenever I make compilation CDs.

There is not much difference between modifying the volume within the mp3 (which is lossless) vs. reripping and modifying the volume within the wav before encoding. A good encoder, like lame, adjusts its threshold for what is audible based on how loud the material is that it is encoding, so the encode should be just as good.

http://www.hydrogenaudio.org/forums/index....showtopic=10637
http://www.hydrogenaudio.org/forums/index....showtopic=30137