Lag introduced after importing mp3 file

I realized today that after importing an mp3 file (with audacity 2.1.2 under W10), there was a slight lag of 5/100 sec introduced at the very beginning of the track. It can be disappointing especially if you are working with a marker track. How is it possible to remedy to that ?

That’s one of the [u]normal side effects[/u] of MP3 compression.

If you know the exact length of the added silence you can zoom-in, select it, and hit the “Del” key.

Or if you know you are going to re-edit the file, don’t export to MP3 (or any other lossy format). When you open a compressed file in Audacity (or with any “regular” audio editor) it gets decompressed. If you re-export as MP3 you are going through another generation of lossy compression, and the “damage” does accumulate.

The problem is that It’s done for learning purposes for people who knows almost nothing about Audacity. I offer them an audio file in MP3, so as to be easily downloaded, associated with a marker file. If both are not synchronized, it will be difficult for those people to re-synchronized them.
I let them know what to do to eliminate that lag, but don’t know how it will be perceived…
So, the solution will be in the future to edit manually the marker file to introduce that lag.

… And thanks, DVDdoug, for your help !

The best solution would be to not use MP3.
If you require small file size (easier to send by email), then OGG format provides similar (or better) sound quality at similar file size, and does not have the problem of “padding” at the start.

Thankxs Steve