Multitrack export: length of mp3 is too long (but only outside AA)

Report · Dec 30, 2019

Hello there,

I have a very weird (and very irritating) bug in adobe audition.

Whenever I export my multitrack file, the mp3 is way longer than the time selection (see screenshots below for all the steps I take).

1: select time frame of 14.37

2: file - export - multitrack mixdown - time selection
3: these settings

4: resulting file in explorer is 18.30; the file is silent after 15.30 (so it's not only too long, but it's also stretched out?)

5: resulting file in AA is 14.27

I have the same problem if I choose (in step 2) for 'entire session' instead of 'time selection'.

Any help would be very much appreciated, because all my clients (and hence, me 😉 get rather confused and irritated about it. Thanks!

PS I use this version of AA

All the best,
Inge

Report · Dec 30, 2019

Short update: I've been testing with settings, and it appears that VBR mp3's are improperly timecoded (atleast in explorer / vlc / spotify). I'm not certain if that's a problem by AA or a default problem of vbr mp3's.

Report · Dec 30, 2019

VBR is certainly the reason. Because the V stands for 'Variable' it's apparently impossible to predict in advance how large the file the encoder will produce is going to be, and many software players simply can't decode the information about this correctly, and display the incorrect time. Does the file sound correct if it's played, and is it at the correct speed? If it does, it's the software you are playing it on that can't cope.If you open the MP3 in Audition, what happens then?

In theory VBR is better to use from a sound quality POV - but in practice the timing issues are the ones that predominate. Since it's MP3 and as compressed as hell to start with, you might just as well use a fixed rate encode, which will come up with more or less the 'correct' time.

More here: https://en.wikipedia.org/wiki/Variable_bitrate