Veepo has kindly provided the trimmed audio clip. Thank you.
It turns out it was
nothing to do with the MP3 file format, but
everything to do with
duration.
In
Mix > Adjust Audio > Adjust length (Auto Remix), ADR first analyses the music to detect patterns in melody, rhythm etc. If too much of the audio clip is trimmed out, ADR is left with insufficient information & throws up the alert Veepo first reported.
The ADR Help file states:
Note: the new audio length cannot be shorter than 10 seconds. It follows, then, that very short clips would not be able to be remixed.
The sample provided by Veepo was
10sec 463ms (0.00.10.463). I tried with a 15sec crop of the same song & there was no error. Admittedly, the remixed result wasn't worth listening to!
Having never previously used this feature to any extent, my observation is that the more that is trimmed out of the original music before remixing, the less successful the remix will be. Forced to used limited information, ADR will do some undesirable things to audio in the remixing process (e.g. change tempo dramatically).
PIX
PIX YouTube channel