Good question.
This error happened to me when I ExtAudioFileRead
a MONO file, using a STEREO client data format in your call to ExtAudioFileSetProperty
.
I don't think ExtAudioFileRead
automatically upconverts mono files to stereo files, if there is a mismatch there I think it fails with this -50 error.
Either make the mono file stereo, or set inFormat.mChannelsPerFrame=1
for the mono files.
Remember, if you don't upconvert, you must account for the mono files in your audiorenderfunction by writing L/R channels from the single mono channel of data.