Volume level matching across MP3s?

Is it possible to match volume levels from track to track in a playlist? It seems that some CDs are recorded at a much lower volume level than others, and when I create a mix of the two I find myself straining to hear a low volume recording, or blasted by a high one.

So, does anyone know of a program I can use to change the average volume level on an MP3 file?

Well, you could install the HiJack kernal and use the "AutoVolumeAdjust"
feature there.

There is a link to HiJack at the tops of this site.


TommyE

If you're running 1.03 you can install Richard Lovejoy's VolAdj. If you're running any of the 2.0 betas you could try installing MLord's HiJack kernel. These perform realtime dynamic compression on the signal. Check them out to see if they fit the bill.

Or you can Normalize the MP3s when you're encoding them from the start. Not something I do because I want to preserve the relative volume levels of the CDs. Even if I have to play with the volume every now and then.

Bruno

Yes it's possible to match the volume level of MP3s, at least to a certain extent. It's not neccesarily that some CDs are recorded at lower volumes than others (although some are) but more to do with the level of dynamic range compression used during recording and mastering of the CD. You can start by using a program such as Cool Edit (www.cooledit.com) and normalize your MP3s to 100% or what is known as 0dB full scale. That will bring the peaks of the MP3 up to the maximum signal level before digital clipping and the rest of the signal levels by the same amount (in dBs). However, such normalization is usually not enough. Assuming that your MP3s are normalized to 0 dBfs, those MP3s recorded with more heavy use of dynamic range compression will have a higher average volume level than those with less dynamic range compression, thus an overall louder or hotter sound. So what you could do is either run the HiJack Kernel or the voladjust on the empeg with possible "pumping" artifacts whereby the volume of the MP3 abruptly changes during playback. Or you could apply dynamic range compression to the MP3s with a program such as Cool Edit. Although I have not used Cool Edit, I'm sure it has some sort of dynamic range compression function.

What is really needed to avoid the pumping artifacts (reported by some using the HiJack kernel) is a "softknee" compression whereby the compression gradually kicks in as it approaches the threshhold (volume level where the compession kicks in) of the compression software. I know that Hyperprism (www.arboretum.com/) supports softknee compression. Preprocessing your MP3s would of course take a lot more time than letting software on the empeg take care of it for you, but the results may be worth it. In addition, preprocessing could potentially introduce additional MP3-related artifacts due to the required conversion from MP3 to wav (for the processing) and then back to MP3 for the empeg.

Stu

A complete primer on this subject is located in the FAQ, here.

Thanks, that clears it up.