Atmos vs 5.1

[LuvMyQuad]

Why would you want to select the 5.1 mix? It's in lossy Dolby Digital AC3 and while it can be at 640kbps (the max for AC3) it is far more likely to be at a lower bit rate and sound poor as a result. Much better in my view to play the 7.1 MLP and have your AVR fold the two sets of rears together to get 5.1 (or 5.0 in my case), it's a trivial thing for your AVR to do and likely an identical mix to the AC3 5.1. I suspect the AC3 is always generated automatically from the 7.1 MLP in the Atmos workflow, even if there is a separate DTS HD MA 5.1 mix on the disc it seems unlikely to me that will be put into the Atmos workflow just for the AC3 5.1.

I agree with what you say. I don't want to choose the 5.1, and i dont. In fact I never rip the 5.1 substream and choose the 7.1, rip to flac, for my son to play on his non atmos system.

What I'm saying is in many cases, the AC3 is the only 5.1 version on the disk. Who is it backward compatible for? How does someone with straight 5.1, (and I mean strictly 5.1 with only 6 channels, not 8 for 7.1) select that playback mode. For such a system, that is the only multichannel option available that can play with no loss of information. Playing the 7.1 will simply lose the rears. There is no menu option to choose 5.1. How does the disc player know to choose that stream? Is it hardwired to look for a 5.1 stream? Default to stereo if it doesn't find one?

I did at one time in the early 2000s i used a Pioneer universal disc player. It didnt play blurays, only SACD, DVDA, etc. It was strictly 5.1. 7.1 was not yet a common format. Can we assume that the 5.1 AC3 stream is meant to provide backward compatibility for that vintage gear? But again, that old Pioneer wouldn't play a bluray at all anyway. By the time blurays arrived, 7.1 gear had become the norm. This is in spite of the fact that there was next to no 7.1 software to take advantage of it.

Once there were 7.1 capable disc players, it's no problem. The player downmixes to 5.1 and feeds the 5,1 AVR

I guess the real question is, in the interest of backward compatability, what scenario will facilitate the playback of that 5.1 stream? Who is that backward compatability targeting exactly?

 

[mandrix]

I'm trying to think if I've ever encountered > 5.1 AC3 on a Blu Ray. I have somewhere an old AC3 encoder but I believe it only does 5.1.
Unless of course you're talking about Atmos DD+.

 

[inspclouseau]

I know where you are coming from and I feel much the same way. Atmos on a non-atmos 5.1 system, like mine, is a hit and miss experience. The recent Bowie Ziggy Stardust, for example, was a disappointment. I don't want to see the dedicated 5.1 mixes disappear but it looks like that will be the case more often than not.

I agree with you wavelength. We are at an age now that because we started collecting music/concert 5.1 dvd's when they first started being produced (1980-something.. ) Any quality 5.1 DTS MA that is from a band we like or music re-dos in 5.1 is a bonus these days.. We likely purchase. We have pretty much run out of room with so much to choose from in our house anyway.. sure love going through them as we play music. Fun.
We do not stream for two reasons. The first is the fact that living in the sticks, we have poor/SLOW, but inexpensive reliable internet. We could pay for another/different outfit but it is OUT of the question to pipe it to us. $$$$$$$$$ The other is the music rental bit that is destroying physical media. We are being nickle and dimed to death as it is. A shame seeing this. We own 3 Oppo players that play our disks flawlessly. One for the 5.3 system. One for a 2 channel Decware tube amp. And the last one that is pretty much not used in the bedroom cabinet. We are all set. As I have said before my intent is not to piss anyone off, my intent is just the truth. A few here have asked smug questions that I just ignore, as they obviously don't want to hear it from me anyway. This outfit is a good one though with a lot of people who obviously just love music......View attachment 1731786967160.jpeg
All the best~ Mike

 

[Owen Smith]

What I'm saying is in many cases, the AC3 is the only 5.1 version on the disk. Who is it backward compatible for?

People with non HDMI AVRs that only have an optical or coax audio in. The blu ray player outputs the AC3 substream to coax and optical, and outputs the entire of the Atmos with all substreams to HDMI. If you are using an HDMI AVR it is the AVR's job to decide how to downgrade or render it to your speaker layout.