I’ve been trying to export to AAC, and I’ve discovered that if I bring the resulting file back in to Audacity, the waveform has shifted (later) by about 20ms. If I do the same export to WAV, the shift doesn’t happen.
If I convert said exported WAV to AAC using iTunes, there’s a smaller (2ms) shift on re-import. If I convert to AAC using Shutter Encoder, there’s no shift at all - the AAC matches the WAV matches the original.
I’ve read some older posts indicating that there’s some wonkiness w.r.t. using the included version of ffmpeg to convert to AAC from Audacity, but not sure if that’s related. I’ve tried “Custom ffmpeg Export” as well as “Entire Project” and “Multiple Files”, but got the same results. And I’m sure all tracks start at 0.0.
This is Audacity 3.7.0, and FFmpeg for Audacity F(59.16.100), C(59.18.100), U(57.17.100).
It’s not the end of the world to have to use another app to convert - but it’s also sort of a pain in the butt.