I think others have run into this but I can’t find a definitive answer to this problem.
24 bit aiff files, if I convert to ALAC (m4a) using Fission Roon reports as Audio Stream Format Not Supported, same source file converted to FLAC is fine. I have the same problem with some 16 bit m4a files, if I convert them to FLAC Roon doesn’t skip them.
At this time, Roon supports mono, stereo and multichannel content in the following formats: MP3, WAV, WAV64, AIFF, FLAC, Apple Lossless, OGG, and AAC at resolutions up to 32 bit 768kHz. Roon also supports DSD64, DSD128, DSD256, and DSD512 in the DSF and DFF formats.
Media that’s not in one of the formats listed above will not import into Roon.
So if the format is supported and you are having problems importing them, there may be some sort of subtle corruption in the wrapper that is fixed when you convert to another format.
Well, I got around it by exporting to AIFF. As for FLAC, I still have some iPods in service, as well as iTunes on other computers, so FLAC doesn’t work for me. And I hate how WAV handles metadata. So, that leaves ALAC and/or AIFF. It’s just weird that Roon doesn’t play well with ALAC as output by Fission.
Yesterday I found out, that the conversion from Fission produced ALAC files to “Apple Lossless” using iTunes, makes the tracks ready to be read by Roon. Before, I thought Fission ALAC and “Apple Lossless” is exactly the same. But, isn’t.
Thus, import your tracks into iTunes and run File–>Convert–>Produce Apple Lossless Version; finally, delete the old/original tracks.