MP3 technical question

[StevePSB]

If you take a 320kbps MP3 file and you have to edit it, when you save it back out as 320kbps does it get re-compressed (and therefore take a drop in quality) or because it is already at 320 will it not compress further and stay at the same quality?

It's puzzled me (theoretically) for a while, but I'm converting some of my vinyl at the moment and wondered about it if I were to re-edit a track that is already an MP3.


StevePSB

[fluffmoln]

Lossy to lossy transcoding will result in further quality loss, no matter the initial/final settings. One could argue about the subjective views on whether that loss is audible or not, but at least the fact remains that it happens.

[retrofuturist]

Greetings Steve,

It's puzzled me (theoretically) for a while, but I'm converting some of my vinyl at the moment and wondered about it if I were to re-edit a track that is already an MP3.

Your best bet, if you can manage it, is to record and edit it as WAV file and then do an MP3 conversion (if you must!) once you've finished any editing.

Retro.

[rollo]

As I understand it, the MP3 format uses frames to encode audio at 44.1 kHz (or whatever). So therefore editing it doesn't have to result in a loss of quality. However, most editors will unstitch it into an uncompressed file for editing, and then recompress it again on the way out. What you need is an editor that works specifically with MP3s.

MP3 Trimmer on the mac claims to be able to do it; I'm sure there are others too.

But yes, your best bet would be to go via AIFF/WAV. And I'm not the sort of person who bangs on endlessly about FLACs and bit-for-bit comparisons either.

[StevePSB]

I've kept my wav files, but I saved my original edit it to MP3, so if I want to edit the wav file I'll have to do the original edit and what I wanted to do now too.

Oh well, not the end of the world to do all the edits I need on the original wav file.


StevePSB

[Frequency]

Depending on the complexity of the edit, mp3trim pro might be useful to you, as it can chop up mp3 files without re-encoding. I use it occasionally for fading out remixes that outstay their welcome (which can be faded out quite effectively with the software) and for separating hidden tracks. It does it all losslessly, so your mp3 will retain the same quality as the original.