How does MiniDLNA handle streaming .m4a audio files (iTunes AAC) to Sony blu-ray disc players?

Per Sony's documentation, AAC audio cannot be streamed over DLNA and my understanding is MiniDLNA does not do transcoding of files (just remuxxing if needed to a streamable container). Yet the files appear labeled as "AAC" on the Son's interface and play back fine.

I also notice that files all played back at what seems to be variable bit rate, even when the original m4a file is a constant bitrate encoding.