Files are longer (in time, not file size in bytes) when I reopen them than when I saved them

[Rossputin]

Hello all,

When I save a file (mp3, constant bit rate at 96 kbps, force export to mono) and then open it again, the file is always around .03 seconds longer than when I saved it.

So a file that was 1:00.000 when I saved is 1:00.029 when I re-open.
A file that was 0:03.000 when I saved is 0:03.030 when I re-open.

Any thoughts as to what could be causing that? I need my audio lengths precise.

Thanks for any help!

[DVDdoug]

MP3 is lossy compression (imperfect). One of the characteristics is that it adds a bit of silence to the beginning and end.

LAME FAQ

[Rossputin]

Thanks. I note in that FAQ that there is a version of the LAME encoder that creates blank space that is less than 10% as long as what the prior encoders added. Is there a way to know what’s being done now or any settings for LAME within Audacity?

I suppose the answer is to just save my files as 0.03 seconds shorter than what I really want!