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So, in your opinion, the Apple tv doesn't have the same issues of volumn fluctuations between Atmos and stereo?
No it don't, at least not at a heart attack, speaker blowing up volume.
So speaking of this there is a subset of the general problem of overall volume differences between stereo and Atmos content on either/both platforms and that is massive volume differences between tracks on the same album for some albums.
A recent example is Avril Lavigne 'Love Sux' (and there are many others), at least on Tidal, and I'd be very interested to know if the below observations are duplicated on Apple Music for this record.
Tracks 1,3,5,6,10 and 12 are loud and tracks 2,4,7,9,11 are quiet.
On Tidal these aren't subtle volume differences, they are gross/jarring. So just playing back the first track into the second says it all.
Mediainfo reports Dialog Normalization (dialnorm) values of -31 dB for the loud tracks and -18 dB for the quiet ones on Tidal.
-31 dB means no level adjustment is being done so that explains why they play at full volume.
Having half the tracks on an album set to play at half the volume simply cannot be what a human engineer would do.
Because of this, the album (on Tidal) is unplayable/unlistenable in it's entirety and any mastering engineer responsible for such an end product under normal circumstances would quickly be out of a job.
I suspect however there is in fact no mastering engineer involved and that the root problem is in blindly using the
Dolby Media Encoder* in a batch encode process, perhaps combined with material that is already heavily compressed that may be problematic for the encoder. That's just a wild assed guess on my part though.
*See 'Loudness - Supports automatic loudness measurement or correction with the Intelligent Loudness metadata generation'
Apple uses Dolby MAT which allows them to circumvent or at least mitigate the root problem.
For Tidal (or Dolby for that matter), there is clearly nobody doing any sort of quality control or even just basic listening to the final lossy files comprising an album encoded for streaming. This (used to be) like level 101 stuff in any studio or mastering environment. IE an assistant engineer or even lower level person would be assigned the job to listen to any final product going out in it's entirety to catch just these kinds of problems. And they happened ALL the time. But of course, Dolby and/or Tidal are just cranking shit out, it's not like anybody cares or anything
It seems that the majority of the encodes don't have this problem but the list of albums that do (at least on Tidal) keeps getting longer.