MP3 quality

Hey there,
Had a quick look in the forum and couldn’t find what I was looking for there so wondered whether you were able to help me with an MP3 conversion issue please? We publish a weekly podcast which sounds awesome when we record with audacity, sounds equally as good when we export to a WAV file and then all good again when I put it through “Levelator”. However what I’m noticing after publishing is that when it gets converted to an MP3 file parts of the recording are going loud and soft. Really annoying as I can’t hear it before then and so can’t edit it. Have you any idea why this might be happening as I’m at a loss!
Thanks for your help…audacity is amazing!
Windows 7
2.0.5

Chris

IMO conversion to mp3 can’t* be responsible parts being unacceptably loud or quiet,
I suspect the track will have those volume variations before conversion to mp3.
You can reduce those variations by more applying more compression (like the levelator) or
if there’s only a few bits, correct them manually with Audacity’s envelope tool




[ * conversion to mp3 can distort the recording with digital artifacts if the “quality”, aka bit-rate, is too low ]

From what can be read at Levelator, it seems that Levelator might do more harm than good to your files:

By taking a global view of the data in various time segments (both long and short), the Levelator automatically balances various audio levels, such as multiple microphone levels in an interview or panel discussion, or segments combined from multiple sessions that were recorded at different levels.

Maybe the various audio levels of your original file are not so well “balanced” by Levelator…

However what I’m noticing after publishing is that when it gets converted to an MP3 file parts of the recording are going loud and soft.

A few more words there. You convert to MP3 and then play it in Windows or Audacity and it does that, or you send it up to the publisher servers and then it goes nuts.

Koz

There is one sense in which MP3 conversion could make the file “unacceptably loud” - if the track is already at a peak of 0 dB (the highest level possible without digital distortion), MP3 conversion - being lossy and inexact - could push the peaks over 0 dB.

In that case you can import the MP3 again into Audacity and use Amplify to bring the peaks down, as long as Default Sample Format in the Audacity Quality Preferences is set to 32-bit float.

I don’t think the above is your issue, but just to say that for export to MP3 it is best to ensure that none of the peaks are above -1 dB. Normalize does that the most easily.


Gale