Hello Core Audio Folk,
We've run into a puzzling problem. Recordings made with a host like
GarageBand using IAA (or Audiobus) have what appears to be aliasing.
When the same recording is made using AUv3 merged to audio there is no
aliasing.
Here is a simple example. A single note is played from an instrument
app and recorded to GarageBand.
The first recording is using the AUv3 plugin of the instrument app, and
is merged into audio using the "Merge" command. This recording is as
expected with a hard cutoff at roughly 7k. Recording here:
https://www.dropbox.com/s/1njnhw9hro8kvwe/4.0_AuV3Recording.m4a?dl=0
This second recording is done using IAA into GarageBand. As you can
see the spectrum is very different with lots of harsh high energy above
11k. It's almost as if the recording was done at 11k and then
resampled to 44.1k. We see the same issue with AudioBus recordings.
Recording here:
https://www.dropbox.com/s/1119us2dhmt0tn3/4.0_IAARecording.m4a?dl=0
Has anyone seen anything like this, or do you have ideas about what
might be going on?
Thanks,
-pat
--
Gregory Pat Scandalis
CTO, acting CEO,
moForte, inc
[email protected]
http://www.moforte.com
650-906-3487
skype: gregory.scandalis
^((1[b3,3][b5,5,#5])|(125)|(145))[6]?[b7,7]?[b9,9,#9]?[11,#11]?[b13,13,#13]?$
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