Fix-up mp3 files?

[storello]

I already have a very basic mp3 collection on a PC with Windows Media Edition but I'm not happy with the mp3s in their original form. The most annoying trait is the huge volume difference between my very old CDs (as early as 1984) and current CDs. The Media9 player will automatically adjust the volume but if I take the mp3s on the road or copy them to CD or DVD the volume problem pops up again because most players/readers won't make this adjustment. To make matters worse the early CDs don't sound much better at higher volume because the mix is so bad.

I have started a new collection of SACDs and DVD-As to replace some of the worst CDs but I'm never going to replace all of them and I'm still a little uneasy about sinking a ton of money into a format that is a long way from public acceptance.

I'm going to be installing a dedicated sound board soon and I'm considering re-ripping everything and use the new software/hardware to create much better and consistant MP3s in the process. This would take a significant amount of time so I'm wondering if someone has an opinion or suggestion on this?

Keep in mind that the music on the PC will only be used for casual listening both at home and via MP3 player or MP3 files copied to CDs or DVDs. I'm not really interested in a lossless format because my primary goal is portability and I can always put the original CD in the CD player if I ever want to hear a lossless recording.

[texasbwfan]

Unfortunately, Ripping your cd's again is the only option you have available. I have an extensive MP3 collection and would recommend that you take a look at the below site:

http://www.chrismyden.com/bestmp3guide.php

I use EAC and the LAME codec to rip all of my CD's. The link I've provided above will provide you with step by step instructions for producing the best possible MP3 tracks. Best of luck to you,

[PewterTA]

:agree:

EAC and LAME are the way to go. If you want slightly better quality, OGG is a better way to go. If you want Lossless compression FLAC is the best way. :T

[storello]

Thanks for the help. OK, I've reviewed the site but the question still remains: Will this process correct defects on the CD? The way I read this is that the goal is to make the most perfect copy of the CD as possible. My problem is that I'm not happy with the quality of the original CD. If I throw 5 CDs from different years into a CD jukebox and play them randomly the result is that the volume radically changes from track to track. Creating a perfect copy of the CDs doesn't do anything to correct the problem. Am I interpreting this correctly?

[PewterTA]

You are correct on that... What you can do is when you rip the CD, you need to normalize it. This way all the tracks are within the same db range. EAC has a normalizing feature in the options. I would rip all the CDs down as .wav's then Then you need to get some sort of wave editor package (Adobe Audition comes to mind), then check out each track from the different CDs and ajust the volume on them until they are all in the same db range. This might require lowering some CDs and raising others. Once you get them all where you like them, then compress them with LAME.

It's going to be a pain...because it is a tedious process, but this will give you exactly what you are wanting.

[storello]

Ugh!! That's what I was afraid you'd say. With such a significant effort to do the "fix-up" I think I'll go through my inventory and see if I can replace the worst of the original CDs first.

The thing that really gets my goat is that it would have been such a simple thing to add a couple of bits of data to the CD standard so the volume could be set correctly by the CD player. Or even just set a standard volume at which all CDs must be mastered. Duh.

Thanks for all your help.

[storello]

I found a slick answer to my volume problems with mp3s :-) Check out "MP3Gain" here: http://mp3gain.sourceforge.net/index.php. The beauty of this program is that it works after the files have been ripped and you can normalize the volume per album rather than per song. It greatly reduces the difference in volume between albums but it retains the original variation in volume that should exist between the tracks on each album. This is especially essential for classical music.

The best part about it, however, is that the change is claimed to be lossless!! Here's an extract of the technical notes from the on-line help in the program:

"Here's the technical reason why it's lossless, and also why the smallest change possible is 1.5 dB:

The mp3 format stores the sound information in small chunks called "frames". Each frame represents a fraction of a second of sound. In each frame there is a "global gain" field. This field is an 8-bit integer (so its value can be a whole number from 0 to 255).

When an mp3 player decodes the sound in the frame, it uses the global gain field to multiply the decoded sound samples by 2(gain / 4).

So if you add 1 to this gain field in all the frames in the mp3, you effectively multiply the amplitude of the whole file by 2(1/4) = 119% = +1.5 dB.

Likewise, if you subtract 1 from the global gain, you multiply the amplitude by 2(-1/4) = 84% = -1.5 dB."

I thought this was such a slick answer that I thew caution to the wind and let it "normalize" all my mp3 files in one big job. It took several hours to analyze the 2300+ files. I did a quick review of the results and then told the program to do an album based adjustment. This, of course, took a while. Once it was done I turned off the mp3player volume adjustment I had been using and started randomly running through tracks. Sure enough, there were still some volume differences (as expected) but I never felt like I had to dive for the volume knob. The quality of my MP3s is mid to low grade and I did not do any direct before and after testing so I can't verify the "lossless" claim but from a purely casual listening perspective they sounded OK to me. They are certainly good enough now for enviroments like the car, background music, or trying to zone out screaming babies while in a middle seat of a 5 hour airplane ride ;-)

The program is completely freeware but it's such a cool little utility that I'll probably send a donation.

[storello]

Oh yeah. One last note. I did notice that the tracks from "Sixty Steps" by Leo Kottke and Mike Gordon either didn't survive the modifications or were messed up before I started. This may indicate issues with copy protected tracks.

This was actually a good find for me since I didn't remember that I had ripped them in the first place. This CD contains the dreaded Sony rootkit. AACK! Now I'll have to pick though my OS to see if simply making a perfectly legal copy of a purchased CD has reeked havoc on my PC. OK, I better stop now before I start unleashing on an issue in which plenty of others have already expressed their disdain.