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[mojave]

I have a Blu-ray audio only disc from 2L called LUX. It won the 2020 Grammy for Best Immersive Audio Album.

If I start playback using the Blu-ray Menu method, then I get these 4 audio tracks to choose from:



If I start playback using the Blu-ray Title method, then I get these 4 audio tracks:



Is there a reason that the Atmos and Auro-3D tracks are not available during Title playback?

[tij]

third and fourth tracks are Atmos and Auro respectively ... if you select those and bit stream them to receiver, receiver will see them as Atmos and Auto

Reason it is not described as Atmos and Auro in MC is simply because MC cannot decode Atmos and Auro (these require licenses)

What MC displays is base layer of those tracks ... which does look a bit strange as I thought Auro base layer was PCM

But your Atmos track base layer is AC3 ... which is lossy ... meaning Atmos track is lossy like what Netflix has ... in this case DTS HDMA is probably better track as it’s lossless

[jmone]

MC uses "ffprob" (part of ffmpeg) to determine the details of the streams.  ffprob is still unable to distinguish the Atmos / DTS:X / Auro meta data extensions from the base layer.  As tij points out, if you select bitstreaming then it will pass the full Atmos etc stream to your AVR.  I'm surprised that ffprob can still not detect these streams as other freeware progs like MediaInfo has been able to do so for years. 

[tij]

MediaInfo does have SDK ... but not sure their licensing model

PS. on some titles MexiaInfo fails to detect DTS-X

[jmone]

I use MediaInfo as part of "Swag of Tools" to get DTS-X and ATMOS info and so far have found it works well.
https://yabb.jriver.com/interact/index.php/topic,106802.msg742303.html#msg742303

[Hendrik]

It seems like that disc actually has two alternate media files on it, 00000.m2ts and 00001.m2ts, they contain the same content, but alternate streams.

00000.m2ts has the streams you are seeing, DTS-HD MA 5.1 and PCM 2.0
00001.m2ts has the missing streams - TrueHD 7.1 with Atmos, and DTS-HD MA 7.1 with Auro-3D

This is a bit unusual but I'm sure they had their reasons - and the menu does it transparently. In MC you can swap between the titles through the OSD as well, or the context menu.
LAV Splitter, which handles title playback, can only stitch files in a timeline, not switch between them on the fly depending on track selection, which is why you only ever get two of the correct titles at  any given time on a disc like this.

The AC3 streams are actually sort-of place holders for the tracks they stored in the other file. Which is a bit weird. They are not mis-identified, and are not a lossy base for the Atmos stream or anything of that sort.
All other analysis above are unfortunately just pure speculation and ... wrong.

If all streams actually play through the menu in MC, I'm a bit proud.

[tij]

My bad ... I thought AC3 were EAC base stream for Atmos like Netflix

I don’t have music Blu-ray’s ... but hiding streams in playlist is quite common on movies Blu-ray which like to hide Japanese streams (think originally BD were aimed at both US and Japanese market ... but then some other distributor got rights for Japan ... so they hide Japanese tracks through playlist)

EDIT: I never saw 2 identical video mt2s but with different audio streams ... that’s an eye opener and very weird way to do things

[mojave]

It seems like that disc actually has two alternate media files on it, 00000.m2ts and 00001.m2ts, they contain the same content, but alternate streams.

00000.m2ts has the streams you are seeing, DTS-HD MA 5.1 and PCM 2.0
00001.m2ts has the missing streams - TrueHD 7.1 with Atmos, and DTS-HD MA 7.1 with Auro-3D

Thanks. I never thought of checking for an alternative title. I now can access the Atmos and Auro-3D tracks when using Title mode, which means I can select the track I want for Particles.

If all streams actually play through the menu in MC, I'm a bit proud. 

All streams playback fine. It is unusual to have a disk with all these streams and with 48, 96, and 192 kHz sample rates.