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LPCM ETA for Arc?


Userlevel 3

LG has released a firmware upgrade for the B9/C9/E9 supporting multichannel PCM passthrough.  This is great except Arc doesn’t support it yet.


Because of this new update, my Apple TV decides it should use LPCM instead of Dolby Digital 5.1 with Atmos enabled resulting in only 2.0 audio for non Atmos content.  The current only workaround is to disable Atmos and enable it when you want to watch an Atmos file.  Very frustrating as the previous firmware had no issue.

 

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Best answer by Ditte 10 November 2020, 16:39

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206 replies

Thanks Sonos!

A question,

Should I go with dts to eac3 transcode or run multi channel 7.1, which is better?

I do have multichannel pcm 7.1 now 🙃

So If I insert a DTS Blu-ray and set my player to pcm/lpcm my rears will work?

Userlevel 7

So If I insert a DTS Blu-ray and set my player to pcm/lpcm my rears will work?

Not only will your rear surround speakers work, but you should also be hearing more audio separation from the Arc because you are going from stereo 2.0 to LPCM 5.1.

Userlevel 2
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Thanks Sonos!

A question,

Should I go with dts to eac3 transcode or run multi channel 7.1, which is better?

I do have multichannel pcm 7.1 now 🙃

Pcm, as otherwise you are converting from one lossy format to another.

So If I insert a DTS Blu-ray and set my player to pcm/lpcm my rears will work?

Not only will your rear surround speakers work, but you should also be hearing more audio separation from the Arc because you are going from stereo 2.0 to LPCM 5.1.

I have hooked an Sony x800 blu-ray player to a Samsung Q90t tv with e-arc. Set the player to pcm. Tried the TV set to pcm and passthrough and the Sonos app only said stereo pcm 2.0. What do I need to change 😭

Userlevel 4
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After doing a lot of testing on the playstation 5 and my PC, I would suggest you DO NOT use LPCM 7.1

Make sure you force all your devices into LPCM 5.1

 

If you run 7.1, you will find that the Arc gets mixed up and outputs Surround channels out the wrong speaker or outputs no sound at all

 

Below I’ve included a visual diagram of this.

If you enable 7.1 LPCM you will find that SR and SL sound is outputted in the RR and RL speakers and the RR and RL sound is not played at all. L, C, R and Sub audio is correct.

 

Sonos will need to release another update to tell devices that only 5.1 LPCM is available, because some devices just default to 7.1 on the new update and some users may not realise they should change it to 5.1

 

 

 

I forced my PS5 to output to receiver as 5.1 but I still miss audio channels (Assassins Creed Valhalla is a good test because dialogue disappears if missing channels).  Is there anything I need to change on the ARC side?

Userlevel 2
Badge +1

My setup is Sonos Arc, sub and 2 play:1’s + LG CX + Apple TV 4K. I have the LG set to HDMI bitstream and Passthrough. Apple TV is set to best available. The new Multichannel PCM seems to be working by looking at the About page in the Sonos App, but it shows Multichannel PCM 7.1, while this setup is still 5.1. Should it not show Multichannel PCM 5.1? The results is the channels are not being output from the correct speaker. Using a Surround Channel Test app on the Apple TV shows the channels all wrong, while before it was all good.

 

Userlevel 4
Badge +7

My setup is Sonos Arc, sub and 2 play:1’s + LG CX + Apple TV 4K. I have the LG set to HDMI bitstream and Passthrough. Apple TV is set to best available. The new Multichannel PCM seems to be working by looking at the About page in the Sonos App, but it shows Multichannel PCM 7.1, while this setup is still 5.1. Should it not show Multichannel PCM 5.1? The results is the channels are not being output from the correct speaker. Using a Surround Channel Test app on the Apple TV shows the channels all wrong, while before it was all good.

 

 

Yes it should be using 5.1 

My guess is that the update Sonos released has a bug or an oversight. I’m sure they’ll update it and after the update one of two things will happen. 1) It will default to 5.1 or 2) It will still show 7.1 and Sonos will implement proper 7.1 to 5.1 downmixing.

I’m leaning towards the 1st option being the more likely outcome

Userlevel 4
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Only just noticed this but any Dolby 5.1 content via my Apple TV 4K box is outputting in multichannel pcm 7.1?

Anyone else.

 

Lg cx setting all set to bitstream/ passthrough eARC on.

Userlevel 4
Badge +7

Only just noticed this but any Dolby 5.1 content via my Apple TV 4K box is outputting in multichannel pcm 7.1?

Anyone else.

 

Lg cx setting all set to bitstream/ passthrough eARC on.

 

I don’t have an apple box to test, but if there is an option in the settings on the apple box to change the channel configuration to 5.1, then use that. 7.1 does not currently work correctly

 

This is such a random bug/issue as well. It implies that Sonos somehow never came across this issue during their testing but how lol?

Userlevel 4
Badge +10

Only just noticed this but any Dolby 5.1 content via my Apple TV 4K box is outputting in multichannel pcm 7.1?

Anyone else.

 

Lg cx setting all set to bitstream/ passthrough eARC on.

 

I don’t have an apple box to test, but if there is an option in the settings on the apple box to change the channel configuration to 5.1, then use that. 7.1 does not currently work correctly

 

This is such a random bug/issue as well. It implies that Sonos somehow never came across this issue during their testing but how lol?

Actually just checking Apple audio settings and I have it set as auto/ atmos available and it says audio will be decoded and sent to my equipment as uncompressed multichannel LPCM.

So looks like it’s doing as it should but as you say a bug currently with 7.1 side of things.

Can anyone confirm that Dolby 5.1 on Apple box should be outputting as multichannel LPCM though? 

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My Nintendo switch (on LG CX) is also outputting Multichannel LpCM 7.1 instead of 5.1. However, when I do the test tones, I can still hear all  of them correctly. Anyone else running into this as well?

Userlevel 4
Badge +7

My Nintendo switch (on LG CX) is also outputting Multichannel LpCM 7.1 instead of 5.1. However, when I do the test tones, I can still hear all  of them correctly. Anyone else running into this as well?

 

you could just change it to 5.1, I have a switch and it can easily be changed if required 

Userlevel 4
Badge +10

My setup is Sonos Arc, sub and 2 play:1’s + LG CX + Apple TV 4K. I have the LG set to HDMI bitstream and Passthrough. Apple TV is set to best available. The new Multichannel PCM seems to be working by looking at the About page in the Sonos App, but it shows Multichannel PCM 7.1, while this setup is still 5.1. Should it not show Multichannel PCM 5.1? The results is the channels are not being output from the correct speaker. Using a Surround Channel Test app on the Apple TV shows the channels all wrong, while before it was all good.

 

Same here all Dolby 5.1 outputs as multichannel pcm 7.1, it should be 5.1, hopefully Sonos release a quick fix.

Userlevel 4
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I have another question if someone knows the answer I have an LG cx and oppo 203 Blu-ray player since this update for LPCM it means I can get better sound with DTS Blu-rays, before I got just stereo 2.0

I now get multichannel pcm 5.1/7.1.

My LG cx cannot passthrough DTS, it will flat out refuse to pass it, my 203 is set to bitstream and when I played a DTS Blu-ray I would get stereo 2.0, now with LPCM update I get the 5.1/7.1 as I said.

Even though the 203 player is set to bitstream is the decoding happening on the player for DTS, Just curious as like I said the cx can’t pass DTS, so does the 203 override my bitstream setting somehow and converts it.

Userlevel 4
Badge +7

I have another question if someone knows the answer I have an LG cx and oppo 203 Blu-ray player since this update for LPCM it means I can get better sound with DTS Blu-rays, before I got just stereo 2.0

I now get multichannel pcm 5.1/7.1.

My LG cx cannot passthrough DTS, it will flat out refuse to pass it, my 203 is set to bitstream and when I played a DTS Blu-ray I would get stereo 2.0, now with LPCM update I get the 5.1/7.1 as I said.

Even though the 203 player is set to bitstream is the decoding happening on the player for DTS, Just curious as like I said the cx can’t pass DTS, so does the 203 override my bitstream setting somehow and converts it.


yes that is correct LG TVs don't support DTS passthrough  https://www.rtings.com/tv/reviews/lg/cx-oled

 

as for why 5.1 is now working, when you connect a hdmi device to another hdmi device they send packets to each other and in tow packet contains data about each devices capability (for example resolution, refresh rate, audio codecs, audio channels etc) and then each device tailors its output based on that for user experience reasons. I guess what's happening now is the ARC reports in this data packet that it supports LPCM, the TV accepts this and the TV tells your bluray player that the ARC supports LPCM and your bluray player then outputs it. Even though your bluray player is set to output DTS I don't think it's outputting dts, it's switched to LPCM or cross mixing  to LPCM

 

 

 

 

Userlevel 4
Badge +10

I have another question if someone knows the answer I have an LG cx and oppo 203 Blu-ray player since this update for LPCM it means I can get better sound with DTS Blu-rays, before I got just stereo 2.0

I now get multichannel pcm 5.1/7.1.

My LG cx cannot passthrough DTS, it will flat out refuse to pass it, my 203 is set to bitstream and when I played a DTS Blu-ray I would get stereo 2.0, now with LPCM update I get the 5.1/7.1 as I said.

Even though the 203 player is set to bitstream is the decoding happening on the player for DTS, Just curious as like I said the cx can’t pass DTS, so does the 203 override my bitstream setting somehow and converts it.


yes that is correct LG TVs don't support DTS passthrough  https://www.rtings.com/tv/reviews/lg/cx-oled

 

as for why 5.1 is now working, when you connect a hdmi device to another hdmi device they send packets to each other and in tow packet contains data about each devices capability (for example resolution, refresh rate, audio codecs, audio channels etc) and then each device tailors its output based on that for user experience reasons. I guess what's happening now is the ARC reports in this data packet that it supports LPCM, the TV accepts this and the TV tells your bluray player that the ARC supports LPCM and your bluray player then outputs it. Even though your bluray player is set to output DTS I don't think it's outputting dts, it's switched to LPCM or cross mixing  to LPCM

 

 

 

 

I mean LPCM 5.1/7.1 seems to work fine on my Blu-ray player it’s just Apple TV 4K that’s having an issue with Dolby 5.1 and outputting as pcm 7.1

Userlevel 2
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My Nintendo switch (on LG CX) is also outputting Multichannel LpCM 7.1 instead of 5.1. However, when I do the test tones, I can still hear all  of them correctly. Anyone else running into this as well?

 

you could just change it to 5.1, I have a switch and it can easily be changed if required 

I don’t see an option to pick 5.1 or 7.1… CX is set to pass through, bitstream, and switch only has Auto, Surround, Stereo and Mono. Have it set to surround (auto has same results). Am I missing a setting somewhere?

Userlevel 4
Badge +10

After doing a lot of testing on the playstation 5 and my PC, I would suggest you DO NOT use LPCM 7.1

Make sure you force all your devices into LPCM 5.1

 

If you run 7.1, you will find that the Arc gets mixed up and outputs Surround channels out the wrong speaker or outputs no sound at all

 

Below I’ve included a visual diagram of this.

If you enable 7.1 LPCM you will find that SR and SL sound is outputted in the RR and RL speakers and the RR and RL sound is not played at all. L, C, R and Sub audio is correct.

 

Sonos will need to release another update to tell devices that only 5.1 LPCM is available, because some devices just default to 7.1 on the new update and some users may not realise they should change it to 5.1

 

 

 

Also some users can’t force it to 5.1, Apple TV 4K for example doesn’t give that option, all Dolby 5.1 content is outputting in multichannel pcm 7.1

Hopefully Sonos are aware of this issue and can fix it soon.

Hi,

I’ve been reading everyones comments and I’m glad I’m not the only one having trouble but mine seems slightly different to everyone else. I have an Apple TV 4K on the latest TVOS with audio set to Atmos I then have my Panasonic GZ950 set to Bitstream. I’m getting full Atmos when I playing anything with an Atmos soundtrack but I’m only recieving Stereo 2.0 PCM for anything other than Atmos. My Panasonic is only ARC and not EARC so not sure if this is the problem. Any help would be greatly appreciated.

Userlevel 2
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Ledzep1,

 

Apple TV 4K is able to output DD 5.1

In Audio Format, click on Change Format, and the new format will become DD 5.1.  The issue with this will be you will not receive full Atmos, and will need to change it back if you are watching a show or movie which you need it to be enabled.

Userlevel 4
Badge +10

Ledzep1,

 

Apple TV 4K is able to output DD 5.1

In Audio Format, click on Change Format, and the new format will become DD 5.1.  The issue with this will be you will not receive full Atmos, and will need to change it back if you are watching a show or movie which you need it to be enabled.

Hi

Thanks, but I was aware of this and getting dolby digital 5.1 and atmos before the LPCM update fine from all content on my apple 4k tv box without having to change any settings.

With this update I still get atmos, but all dolby is not down mixing correctly to multichannel PCM 5.1 instead it's outputting 7.1.

That may be a temporary solution I agree.

Ledzep1,

 

Apple TV 4K is able to output DD 5.1

In Audio Format, click on Change Format, and the new format will become DD 5.1.  The issue with this will be you will not receive full Atmos, and will need to change it back if you are watching a show or movie which you need it to be enabled.

Hi

Thanks, but I was aware of this and getting dolby digital 5.1 and atmos before the LPCM update fine from all content on my apple 4k tv box without having to change any settings.

With this update I still get atmos, but all dolby is not down mixing correctly to multichannel PCM 5.1 instead it's outputting 7.1.

That may be a temporary solution I agree.

Thanks for the reply khaz22 and ledzep1. I have been doing this ever since I bought the Sonos Arc but I was under the impression that this latest update would fix this and I wouldn’t need to keeping switching Is that not the case? 

Userlevel 4
Badge +10

Ledzep1,

 

Apple TV 4K is able to output DD 5.1

In Audio Format, click on Change Format, and the new format will become DD 5.1.  The issue with this will be you will not receive full Atmos, and will need to change it back if you are watching a show or movie which you need it to be enabled.

Hi

Thanks, but I was aware of this and getting dolby digital 5.1 and atmos before the LPCM update fine from all content on my apple 4k tv box without having to change any settings.

With this update I still get atmos, but all dolby is not down mixing correctly to multichannel PCM 5.1 instead it's outputting 7.1.

That may be a temporary solution I agree.

Thanks for the reply khaz22 and ledzep1. I have been doing this ever since I bought the Sonos Arc but I was under the impression that this latest update would fix this and I wouldn’t need to keeping switching Is that not the case? 

Well for me I have never needed to change settings, I have always got atmos and dolby 5.1 perfectly fine on the auto settings via apple tv 4k.

But since the LPCM update, it works as intended in outputting LPCM for dolby 5.1 content but it is outputting as multichannel PCM 7.1, it should be 5.1.

If you go into the apple 4k tv settings you will see that on auto settings the apple TV states it sends audio as uncompressed LPCM which I believe is better quality to dolby 5.1.

Its just not doing it correctly and outputting as 7.1, not sure where the issue lies.

 

I think I should create a separate thread for this as Sonos might not be aware of an issue.