Just upgraded my Mac Mini M1 to Sequoia and to my delight, I’m able to output Bitstream Atmos via Apple Music and Apple TV+. Can you reach out to Apple to see if you can access
Encoded Bitstream Output? Perhaps even send it DTS or DSD?
I feel Roon is falling behind in the whole atmos area. I listen to atmos streams from tidal or apple directly from their apps. Unfortunately can’t do this on Roon.
Perhaps they doubt the availability of legal sources. Here’s one:
You can play it back in QuickTime Player on Mac in full 7.1.4 and it shows up as Dolby Atmos/D+ on my Receiver. On the Mac “Audio MIDI Setup” it shows as “Encoded Digital Audio 192kHz”. I think QuickTime Player is a wrapper around the AT/VT APIs, so this should all be doable, shouldn’t it?
00000000: 7472 616b 0000 005c 746b 6864 0000 0003 e093 a4dc e093 a4dc 0000 0002 0000 0000 trak...\tkhd....................
00000020: 0004 3b60 0000 0000 0000 0000 0000 0001 0100 0000 0001 0000 0000 0000 0000 0000 ..;`............................
00000040: 0000 0000 0001 0000 0000 0000 0000 0000 0000 0000 4000 0000 0000 0000 0000 0000 ....................@...........
00000060: 0000 0024 6564 7473 0000 001c 656c 7374 0000 0000 0000 0001 0004 3b60 0000 0000 ...$edts....elst..........;`....
00000080: 0001 0000 0000 0014 7472 6566 0000 000c 6368 6170 0000 0003 0001 25c4 6d64 6961 ........tref....chap......%.mdia
000000a0: 0000 0020 6d64 6864 0000 0000 e093 a4dc e093 a4dc 0000 bb80 00cb 2200 55c4 0000 ... mdhd..................".U...
000000c0: 0000 002e 6864 6c72 0000 0000 0000 0000 736f 756e 0000 0000 0000 0000 0000 0000 ....hdlr........soun............
000000e0: 736f 756e 6420 6861 6e64 6c65 7200 0001 256e 6d69 6e66 0000 0010 736d 6864 0000 sound handler...%nminf....smhd..
00000100: 0000 0000 0000 0000 0024 6469 6e66 0000 001c 6472 6566 0000 0000 0000 0001 0000 .........$dinf....dref..........
00000120: 000c 7572 6c20 0000 0001 0001 2532 7374 626c 0000 0056 7374 7364 0000 0000 0000 ..url ......%2stbl...Vstsd......
00000140: 0001 0000 0046 6563 2d33 0000 0000 0000 0001 0000 0000 0000 0000 0006 0010 0000 .....Fec-3......................
00000160: 0000 bb80 0000 0000 000e 6465 6333 1800 200f 0000 0000 0014 6274 7274 0000 0000 ..........dec3.. .......btrt....
00000180: 000b b800 000b b800 0000 0018 7374 7473 0000 0000 0000 0001 0000 21db 0000 0600 ............stts..........!.....
000001a0: 0000 bc98 7374 7363 ....stsc
This part of the track atom looks straightforward, but the STSC is kinda big.
Then
0000 6810 7374 636f ..h.stco
is another big atom which is followed by:
00012660: 7564 7461 0000 001d 6e61 6d65 446f 6c62 7920 4174 6d6f 7320 372e 312e 3420 4444 udta....nameDolby Atmos 7.1.4 DD
00012680: 2b00 0002 bb74 7261 6b00 0000 5c74 6b68 6400 0000 02e0 93a4 dce0 93a4 dc00 0000 +.
This is a lot of audio metadata, which I expect is really important for the correct playback of the Atmos track.
I think if Roon wants to keep my subscription after this year is up, the way to do it will be to petition Apple to be able to output at least EAC3 Atmos Bitstreams from their application over HDMI and be able to render TrueHD Atmos as EAC3 Lossy Atmos at some nice high bitrate (whatever Apple allow). If they can directly render TrueHD that would be even better. The music is provided in MKV and MP4 containers from companies like https://immersiveaudioalbum.com in addition to music I have extracted from my own physical media.