Dolby Atmos compatibility with 5.1 systems

[wavelength]

Wish it had 5.1 in addition to Atmos. I hate when they do that.

I only have a 5.1 system but I don't mind an Atmos-only mix. It always plays fine. I really don't see the need for a dedicated 5.1 mix. I was reading the comments in the Abbey Road poll and some 5.1 people preferred the Atmos mix. They said it sounded better as the 5.1 mix than the dedicated 5.1 mix. I'll have to check that out.

 

[knifeman]

I only have a 5.1 system but I don't mind an Atmos-only mix. It always plays fine. I really don't see the need for a dedicated 5.1 mix. I was reading the comments in the Abbey Road poll and some 5.1 people preferred the Atmos mix. They said it sounded better as the 5.1 mix than the dedicated 5.1 mix. I'll have to check that out.

I've passed on Atmos only mixes because I don't have capability to play it. Maybe I'll listen to Abbey Road in Atmos just out of curiosity. Still, in my head I'd be thinking that this isn't exactly the way it was meant to be heard.

 

[wavelength]

I've passed on Atmos only mixes because I don't have capability to play it. Maybe I'll listen to Abbey Road in Atmos just out of curiosity. Still, in my head I'd be thinking that this isn't exactly the way it was meant to be heard.

I hope you like it! I'm betting that you are hoping that you like it too. Otherwise you could be missing out on a lot of surround titles. Let us know what you think.

 

[Monkish]

I've passed on Atmos only mixes because I don't have capability to play it. Maybe I'll listen to Abbey Road in Atmos just out of curiosity. Still, in my head I'd be thinking that this isn't exactly the way it was meant to be heard.

I'm in the same boat as you -- I don't know when or if I'll ever have an Atmos set-up, and I'm much more comfortable with dedicated 5.1 mixes, ones that were specifically designed with my system in mind, than a downmix where the placements are determined by algorithm. For example, I've gotten to hear some Tidal/Apple Atmos songs as downmixes, and while I enjoy them (some of them very much), I'm always distracted if something sounds weird or oddly balanced -- I start thinking "are those vocals supposed to be shoved in the left rear, or did the downmix algorithm screw things up?" I really hope the rise of Atmos doesn't mean the end of dedicated 5.1.

 

[LuvMyQuad]

I do have Atmos capability, but before that point, I played quite a few Atmos mixes rendered as 5.1, and to my ears and with my system I have no issue with it. My understanding is, there is no downmix algorithm in the sense you speak of. The mix is delivered as straight 7.1 (5.1 if streamed) with imbedded metadata. The metadata directs the Atmos processor to move specified "objects" from the floor channels to the heights. So it subtracts and adds. If the metadata is ignored, as would be the case on a non Atmos system, everything stays where it is. Nothing is lost. Nothing is moved.

If someone knows the specifics better and decides I'm wrong on this, please speak up.

Some of the best 5.1 I've heard is from Atmos releases rendered as 5.1.

 

[sjcorne]

My understanding is, there is no downmix algorithm in the sense you speak of. The mix is delivered as straight 7.1 (5.1 if streamed) with imbedded metadata. The metadata directs the Atmos processor to move specified "objects" from the floor channels to the heights. So it subtracts and adds. If the metadata is ignored, as would be the case on a non Atmos system, everything stays where it is. Nothing is lost. Nothing is moved.

I think that's true, but the objects being scaled-down to the floor speakers can result in sounds no longer being localized - so if there were a sound effect mixed to the center of the ceiling array in Atmos, the resultant 5.1/7.1 downmix would place that element in the middle of the room.

Another thing I'm not sure of is what happens when you play a 7.1 mix through a 5.1 system - does it put all that information in the rears, or does it put the side channel information in the 'phantom' sides?

Check out the song "Wah-Wah" from George Harrison's All Things Must Pass - in the Atmos/7.1 mix, the first guitar riff comes from the side left speaker, whereas in the dedicated 5.1 mix it comes from the 'phantom' left side (in between rear left and front left). However, if you play the Atmos mix off either the Blu-Ray disc or streaming through a 5.1 system, that guitar comes entirely from the left rear speaker.

 

[LuvMyQuad]

I think that's true, but the objects being scaled-down to the floor speakers can result in sounds no longer being localized - so if there were a sound effect mixed to the center of the ceiling array in Atmos, the resultant 5.1/7.1 downmix would place that element in the middle of the room.

In the example above, wouldn't it depend on which floor channels(s) the object was placed in originally? If it were in the four (or five) floor channels to begin with, then yes, it would appear there in the 5.1 rendering as well and appear to come from the center of the room. If it were only in the left front channel in the Atmos mix and then processed as an object to come from the heights, it would appear to come from the center height position. But if that Atmos mix is rendered in 5.1, it would appear to come from the left front channel alone.

Another thing I'm not sure of is what happens when you play a 7.1 mix through a 5.1 system - does it put all that information in the rears, or does it put the side channel information in the 'phantom' sides?

I always thought the side info was added to the rears. But I'm not 100% sure either.

Check out the song "Wah-Wah" from George Harrison's All Things Must Pass - in the Atmos/7.1 mix, the first guitar riff comes from the side left speaker, whereas in the dedicated 5.1 mix it comes from the 'phantom' left side (in between rear left and front left).

The 7.1 and the 5.1 are different mixes entirely. So this is understandable.

However, if you play the Atmos mix off either the Blu-Ray disc or streaming through a 5.1 system, that guitar comes entirely from the left rear speaker.

Again, because the side information in a 7.1 mix (Atmos or not) reverts to the rears when played as 5.1. This makes sense too.

 

[sjcorne]

The 7.1 'sides' being added to the 5.1 rears seems be why people prefer Atmos over the dedicated 5.1 stream on some of the recent Apple releases (All Things Must Pass, Plastic Ono Band, etc), but I find it can make the resulting 5.1 presentation too rear-heavy.

I've also found that the content directed to the center channel can change when an Atmos mix is played back on a 5.1 system. Check out some of the recent Steven Wilson Atmos mixes (Free Hand, The Future Bites, etc) - if you play them in Atmos, the center channel contains eerie isolated vocals (as is typical for his surround mixes). However, if you play back in 5.1, there's kick and snare drum directed to the center speaker along with the vocals.

This isn't intended as a critique of the Atmos format (in fact - I think the Atmos presentation of Air's 10,000 Hz Legend is miles ahead of the dedicated 5.1 mix, even with just two height speakers), I just find this whole 'adaptive to however many speakers in your setup' concept interesting and worthy of discussion.

 

[zeerround]

I'm forgetting the gory details at the moment but I did discover that Tidal Atmos, which is 15 (fixed) objects and one channel, LFE, so 9.1.6 didn't fold down as I expected, which is causing me to author up-remixes for 7.1.4, expecting playback on 7.1.4 or below, rather than 9.1.6. I think I posted about it here somewhere...

There are a bunch of downmix settings in Dolby, and Dolby Atmos. so your mileage could vary, depending on who did the encoding, and we have already established that streamers do their own Atmos encoding, with Apple not even using Atmos for their "Spatial Audio" stream via headphones.

 

[zeerround]

I wrote:

"​

One of my assumptions about ATMOS rendering 9.1.6 targeted audio on systems with fewer channels turns out to be wrong. ​

​

e.g. I assumed that something placed in the "Wide Left" and "Wide Right" 9.1.6 channels would be panned between front and sides in 7.1.x system. It's not. The "Wide Left" and "Wide Right" are sent only to the fronts.​

​

Oddly, audio targeted for the MID Height Speakers in 9.1.6 IS panned between Front and Rear Height Speakers in a 7.1.4 system​

​

(5.1 and 5.1.4 rules I'm still researching).​

​

At the moment I'm stumped as to how to mix for any atmos speaker config.​

​

For instance in my up-remix I had the piano stem (upmixed by SpecWeb) routed as quad to the Wide Fronts and Rears in a 9.1.6 layout. Listening the 9.1.6 the piano is clearly coming from a wider source than things in the fronts, but listening lessor numbers of channels the Piano will come from the same position as the fronts.​

​

To achieve the same effect I could Pan the piano between fronts and sides, but then the Wide channels would go unused in 9.1.6​

​

Maybe it would work if I used Atmos objects, vs. channels, but the AWS encoding service doesn't support objects. "​

I may still have a piece(s) of paper on my desk documenting the downmix to 5.1. I'll look.

 

[Audiowannabee]

I'm forgetting the gory details at the moment but I did discover that Tidal Atmos, which is 15 (fixed) objects and one channel, LFE, so 9.1.6 didn't fold down as I expected, which is causing me to author up-remixes for 7.1.4, expecting playback on 7.1.4 or below, rather than 9.1.6. I think I posted about it here somewhere...

There are a bunch of downmix settings in Dolby, and Dolby Atmos. so your mileage could vary, depending on who did the encoding, and we have already established that streamers do their own Atmos encoding, with Apple not even using Atmos for their "Spatial Audio" stream via headphones.

Well pretty much no one here is listening thru headphones...

 

[zeerround]

No joy on the paper hunt, but probably a better idea, I will post some atmos channel id tracks, and you can test your own system to see where the sounds sounds come out.

(but won't address possible different downmix settings at encoding time, or maybe differences between object and channel downmix )

 

[zeerround]

h**ps://drive.google.com/drive/folders/1TPkMkgEHvzCQukk5I8ZW-L_H7VUh1bqe?usp=sharing

(change the ** to tt)

Dolby Atmos 9.1.6 and 7.1.4 channel tests. DTS:X 7.1.4 and 5.1.4 channel tests. You can play in VLC (bitstream to your AVR over HDMI) or however you play video files with encoded sound.

Use to 1) check your system is setup the way you think it is 2) Find out how immersive sound targeted for higher channel count systems downmixes on your rig.

Z

 

[zeerround]

Just noticed there is a "pinned" 6 page long discussion along similar lines to this thread, here:

https://www.quadraphonicquad.com/fo...ms-tests-results-questions-experiences.29057/