I keep running into this problem when saving a wav to an mp3. I work for an indie radio station that requires all the uploads to be at -0.1dB. I do this through applying a hard limiter on the wav file, then saving as an mp3. This works fine, but if I close the file out of audition then re-open it to check it, it's no longer limited to -0.1, it's hitting 0db and clipping. Sometimes the track length has changed too, usually by around 0.08s but I need it to be exact. I've also tried saving it as an mp3 first and then hard limiting it, but that makes no difference. Is there something in my settings I need to change? Is there an easier way to do what I'm doing than using the limiter? Thanks!
If you encode anything to MP3 there is no guarantee that you'll ever get amplitudes that exact, because the encoding is a lossy process. Timing changes often come about by using VBR instead of CBR, so it's worth making sure that you aren't doing that. I never try to save to MP3 with less than 1dB of headroom, for just this reason.