Please read if you have encountered issues with 7.1 LPCM playback on Sonos via an LG TV

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A

I experience this. I'm also in a beta software test now so this is cross-posted there.

 

1. Watching a series of episodes (Netflix and Amazon prime video, sometimes the audio for a new episode plays from wrong channel. Dialog from rear right, back left has background music, arc sound bar has traditionally surround audio.
2. Stopping episode and then resuming fixes the mix
3.
4.

Tell us what happened:
tv model LG OLED65C2AUA
Watching via apple tv 4k
Sonos arc connected via eARC
Experienced watching episodes of "I think you should leave" on Netflix and "Oh Cook!" On Amazon.

Corry P
Userlevel 7
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Hi @ajdz859 

Not only is Beta software irrelevant to any discussions here on the forum, it is also against the forum rules. Please don’t discuss Beta experiences here.

It’s clearly not something you want happening, however, so I recommend you feed this back to the Beta team - though it sounds like you have already. Thanks.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
A

@Corry P your response is confusing and frankly, unnecessarily dismissive of the relevant topic of THIS thread. Are you suggesting that the LG TV issue is resolved? Your initial feedback point is well taken, but overlooks that I have pointed out that I'm experiencing the sound channel mapping issue which is on topic for this thread.

H
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Thank you.

 

So is it a special Apple TV (handshake) problem with no chance of a solution from Sonos side?

 

It is not a very big problem because it does not happen very often.

E
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Speaking to the original question, I do have problems with mismapped channels. I think I’ve narrowed the issue down to the Apple TV 4K 2021. It’s the only source device experiencing the issue. The issue is that each front channel seems to come out of all front speakers at the same time, and each rear channel seems to come out of both rear speakers at the same time. I’ve also submitted this issue to Apple, FB13404270, in case any Apple devs are lurking. Since this only seems to happen with Apple TV, I don't think it’s a problem with Sonos, but I’m posting here just in case.

My setup:

Apple TV 4k 2021 → HDMI → LG CX 55” → HDMI eARC → Sonos Beam Gen 2 + 2x One SL as 5.0 surround

Configuration:

Apple TV:
Audio Output: Receiver Speakers
Audio Format: Auto, Atmos Available (Change Format: Off)
Audio Mode: Auto

LG CX:
Sound Out: HDMI ARC
HDMI Input Audio Format: Bitstream
Digital Sound Out: Pass Through
eARC: on

---

Your LG TV model number: LG CX 55”

Your media source device name and model number or TV app that the issue was noticed on, and the name of the movie/show that was affected: Apple TV 4K 2021, Netflix Test Patterns: https://www.netflix.com/watch/80164785 (see here to show it in the Apple TV Netflix app: https://www.tomsguide.com/how-to/how-to-use-the-netflix-test-screens)

Models of any other HDMI devices connected to the TV (if applicable): Nintendo Switch, PS5, which are off during testing but independently map channels correctly

The confirmation number of a Sonos system diagnostic submitted while the affected media was playing and 7.1 LPCM was reported in the Sonos app.: 2109599949

B

I can confirm, went from 2021 to 2022 model and 5.1 shows correctly. However that now means I get the problem of sound dropouts on MPCM 5.1 signals reported elsewhere in this forum 

Hi, could you do me a small favor and verify something for me? I have the same issues with the 2021 ATV4K (2ndgen) and I’d like to be completely sure the that the 2022 ATV will solve my issues before I upgrade. Could you please play some 5.1 content on your Apple TV and go into the LG settings → general → channels (or whatever the english translation for that menu point is, should be the 3rd under general) → channel search (it’s the 1st menu point in that submenu) and now press “1” on your LG remote for 5 times: this will open the HDMI diagnostics, now navigate to DVI/HDMI status and expand that part, now you will see a new screen with a “general” subsection at the top left corner, here it will now say either PCM 8ch (if it’s still bugged) or (I pray to god) PCM 6ch. Would be really nice if someone with the newest ATV4K and LG CX/C1/CS/C2 could verify this for me (also “passthrough” should be selected in the audio settings instead of “auto”)!

S
Badge +1

Hi @efrem81 & @JefDc 

Please describe the way in which your 7.1 playback results in mis-mapped channels. Thanks.

 

Hi

Is there any particular content/ test pattern we could use to test this issue, as I presume its not easy to hear if there is an issue? 

I have an LG CX and all content over HDMI, be it oppo203, apple tv 4k, all the DD 5.1 audio is ouput as multichannel pcm 7.1, but as you say LG seems to up convert it.

 

If the Oppo can play an MKV file, try this DTS-HD Master Audio 7.1 Sound Check:

https://thedigitaltheater.com/tools/

 

You should be able to AirPlay this 7.1 AAC MP4 file from an iOS device to your Apple TV 4K:

https://www2.iis.fraunhofer.de/AAC/7.1auditionOutLeader_v2_rtb.mp4

 

I was able to test the 7.1 file via AirPlay to my Apple TV 4K. My set up is a LG CX + Beam (Gen 2) + 2 One’s as rears. When the file plays the Rear Surround Left, it comes out of the Rear Left and Rear Surround Right comes out of the Rear Right. The Sonos app shows Multichannel PCM 7.1 

I also did the Uncompressed 7.1 audio test on my Xbox Series X and the same thing happens. The Rear Surround Left comes out from only Rear Left and vice versa. Sonos app does Multichannel PCM 7.1 as well

Uncompressed 5.1 test on Xbox Series X does play out of all the speakers correctly, but app shows as Multichannel PCM 7.1

I do have a PS5 set via LPCM 5.1 giving the Multichannel PCM 7.1 reading as well but did not submit a diagnostic for this one.


I’ve submitted 3 Diagnostics:

  • 658268328 - 7.1 audio file via AirPlay to Apple TV 4K
  • 1059676763 - 7.1 Uncompressed test via Xbox Series X
  • 1377827016 - 5.1 Uncompressed test via Xbox Series X


 

Airgetlam

This is a Sonos community board. I’d be terribly surprised if any developers, including Sonos developers, are ‘lurking’. 

I am happy, however, as an owner of several Apple TVs myself, that you’ve reported the issue to Apple,

Bruce
E
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This is a Sonos community board. I’d be terribly surprised if any developers, including Sonos developers, are ‘lurking’. 

I am happy, however, as an owner of several Apple TVs myself, that you’ve reported the issue to Apple,

Corry P works for Sonos and specifically solicited this feedback from the community in the original post.

S
Badge +1

Hi @slongChez 

 

We don’t “drop” any channels - we downmix them so the channels that don’t have physical speakers to go to end up coming from equivalent speakers (so a side channel would play through the front and back speakers of that side, resulting in still appearing to come from the side). But yes, the end result may well be indistinguishable.

 

This is not the case for me. The side channel audio only comes out from the rear speakers.

Apologies - this was pure supposition on my part, and it turns out I was incorrect. Unfortunately, there isn’t any internal documentation for me to consult yet .

The rear surrounds (LRS, RRS) are mixed together with the surrounds channels (LS, RS) and the result is played solely from the satellite pair, rather than the surrounds channels (LS, RS) being mixed to both front (LF, RF) and the satellites, as I suggested. What you experienced is the expected behaviour.

Apologies again for any confusion. 


Thanks for clarifying this Corry! Curious to what the results from the diagnostics return back.

M
Userlevel 3
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I’m not sure if this is the same thing. I have a Beam Gen 2 and a Sub Mini running off a ATV 4k 3rd Gen and an LG C2. Sometimes the Beam will play surround channels only with no centre (vocals). I usually need to reboot everything to get it working again. This isn’t just with 7.1 audio though. 

S
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Just for information, I don't have problems of wrong audio channels, but with lg C1, arc, sub gen 3 and two one as surround the “source also consistently shows as “multichannel 7.1” problem is completely solved with Apple TV 4K 3rd generation (2022) in fact now always shows "multichannel 5.1" when the track is in that format

 

Seriously? I have my CX and ATV4K 2nd Gen and of course still have the 7.1 issue on it. If you had the previous version and were getting 7.1, did you happen to notice an audio difference at all now that the new model shows proper 5.1?

I don’t have the misaligned audio issues with my full setup at all.

Corry P
Userlevel 7
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Hi @slongChez 

All 3 diagnostics show 7.1 LPCM being played - although not normal, this is what we now expect to see from an LG TV.

 

Hi @rbouley 

You may want to try retuning TruePlay, if you have it activated.

Settings » System » [room name] » TruePlay » TruePlay Tuning.

 

 

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
S
Badge +1

Just for information, I don't have problems of wrong audio channels, but with lg C1, arc, sub gen 3 and two one as surround the “source also consistently shows as “multichannel 7.1” problem is completely solved with Apple TV 4K 3rd generation (2022) in fact now always shows "multichannel 5.1" when the track is in that format

 

Seriously? I have my CX and ATV4K 2nd Gen and of course still have the 7.1 issue on it. If you had the previous version and were getting 7.1, did you happen to notice an audio difference at all now that the new model shows proper 5.1?

I don’t have the misaligned audio issues with my full setup at all.

no, I didn't notice any audio difference, simply now the writing on the Sonos app is the right one. 
I had the previous Apple TV (2021) and I too was affected by the 7.1 bug instead of 5.1 read on the app, all resolved with Apple TV(2022)


Strange, wonder what it’s doing different compared to the previous version.

Mutiny
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LG CX + Beam Gen 2 + PS 5 here.

When switching to PCM on console the app shows Multichannel 7.1. Sound feels flat, volume is low and it feels like i am losing surround too, not sure how to describe it.

Compromising to Dolby or DTS on console gives me the best result though, sound difference is quite amazing. Not sure of how much of a “compromise” it is from a technical standpoint, but it is what it is.

Diagnostics - 1015551901.

Thank you very much for looking into this! 

Hope this helps!

H
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@RangerDog 

 

I have had these problems with the newest Apple TV.

But I keep my fingeres crossed that one of the newest Apple TV updates has solved the problem.

 

I’m not sure, because it has happed to me only one or two times a month.

H
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Noone?

 

Yesterday in PrimeVideo again - 5.1 Multichanel was recognized as Stereo PCM = I cannot hear voices, only music.

 

Even restarting the app did not help. Only after playing a stream with real Stereo PCM the 5.1 Multichanel on Amazon was recognized correctly.

 

Airgetlam

I’d think the opposite. There’s no financial relationship between the two companies, so I would expect LG to listen more to people who have actually spent money with LG, rather than some random third party providing a competing product to their own sound bars. 

Bruce
S
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Hi All,

We feel it’s worth pointing out that, from a technical standpoint, there’s nothing wrong with LG sending a 6 channel stream via an 8 channel mapping - nothing is lost, and all channels appear to be playing from the correct speakers. We don’t view this as a fault that needs to be fixed, just a more unusual choice made by LG in this case.

When Sonos is given the opportunity to do the decoding, however, we will apply a gain boost to increase the volume, which is why DTS or DD will sound louder than LPCM. LG’s converting to LPCM may well be an attempt on their side to homogenise the volumes across various sources and compression types.

In the end, it’s really up to you, the end users, and what you prefer to listen to.

It does seem strange to me that the Passthrough setting on the TV does not seem to actually passthrough - this still might be something you’ll find worth reporting to them.

I hope this clears things up.

 

There’s some weird things going on with Passthrough for sure. If I set it to Auto, my Xbox won’t give the options for Uncompressed 5.1 and 7.1. If set to Passthrough, the options are available again.

I’m guessing it’s just best to leave it set to Auto instead of Passthrough if it isn’t doing what it’s supposed to.

M
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I have same issue, LGCX, Beam 2, sub, 2x 1 sl’s. Blu ray 5.1 dts-hd discs play in multichannel 7.1pcm.

I can get the standard dts 5.1 surround via a work around (optical out on the ub820 conv to hdmi), but it means swapping out the hdmi leads at the back of the soundbar each time i want to watch a dts film.

My question is: 

Given the 7.1 to 5.1 down mix issue? Which is better, multichannel 7.1pcm or the just the standard dts 5.1 surround ?

Thanks M

A

Apple tvOS 16.2 didn’t solved the issue and tvOS 22 from LG CS 2022 neither. Happy new year :(

S
Userlevel 3
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I’m not sure whether channels are being played back correctly but I definitely get the app reporting 7.1 when I play 5.1 content


LG 65CX

Source: Apple TV 4K (2021)

Content: Disney+ Dolby 5.1 Walking Dead

Also plugged in to the TV: PS5
 

Diagnostic 1721739950

J

LG C2 2022

Netflix via Apple TV 4K (first gen)

Sex Education: S2E7

Apple TV into HDMI 1, HDMI 2 eARC out into Beam Gen2

Diagnostic: 2018107307

issue: front and rear channels swapped in playback

S
Badge +1


It’s definitely 6 CH, just checked;

 

GENERAL

HDMI3, HPD: HIGH, 5V : HIGH, R×Sense : HIGH 3840×2160P @ 23.97Hz RGB 8BIT NODATA PCM 6Ch 48000HZ

HDMI Mode : HDMI, HDR Type : SDR

 

 

Than you both very much! This has plagued me for so long now that I’m willing to spend the money and just buy a new Apple TV…

Just beware of the sound drops with 5.1 signals if you have a beam

Thanks for the heads up, we have a Sonos Arc 5.1 Setup, I hope everything will be fine!

 

Did you end up upgrading after all?

Corry P
Userlevel 7
Badge +18

Hi @ste_ms 

Thank you, but to clarify, we want to know about any instances where the channels are definitely playing from the wrong locations.

It seems the LG TVs will convert to 7.1 anyway, but if there are issues with channels mapping to the wrong location we’d really like to know about it.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein

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