This is a really curious issue.
From what I’ve been able to tell we haven’t been transcoding AAC 5.1 to AAC 2.0 during Direct Stream as far back as 3.53.0. I’ll go back further over time to determine if there was a regression in the UI.
A mix of working and non-working files points to an issue in the encodings themselves.
I know how baffling it can be when working and non-working files are encoded ~identically but behave differently or, why some files work differently in some video players.
There are pointers in the Web app and PMS code that suggest this is the intention but neither is enforcing it. I’ll need to do some research on the non-working file and the history of the this code to determine if we’ll force AAC 2.0.
In the meantime, if you’re feeling adventurous, you can carefully remove onlyTranscodes="true" from Web.xml system profile then restart PMS. The Web app will still try to direct stream the audio but PMS will force it to transcode. The profile location isn’t advertised broadly but there is some information available. Please be aware that any edits to this file may be wiped out when updating PMS.
