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Multichannel PCM on Arc



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@GuitarSuperstar Is there a setting on your BR player to force a 5.1 output? Just out of curiosity, that fixed this exact issue in my experience. Do ARC/eARC sound bars use EDIDs or some kind of config file to tell TVs what their capabilities are? I wonder, is the problem that Sonos isn’t giving proper format instructions to upstream devices or that the sound bar isn’t properly mixing 7.1 down to 5.1. 

Userlevel 7

I just performed the “DTS Sound Check” from a 2015 DTS Demo Blu-ray disc. I am playing this on a Panasonic DP-UB820 UHD player with DTS set to PCM. These are the results:
 

DTS Sound Check 5.1
All channels played the test tones correctly. The Sonos app reported “Multichannel PCM 7.1”.



DTS Sound Check 7.1
All channels played the test tones correctly EXCEPT the Left Rear and Right Rear Surround channels. The surround test tones only played out of the Left Side and Right Side Surround channels. The Left Rear and Right Rear Surrounds were completely silent. The Sonos app reported “Multichannel PCM 7.1”.


So it appears the Sonos Arc is not playing the Left Rear and Right Rear surround channels when playing a DTS-HD Master Audio 7.1 track.

Userlevel 7

@FishyD I have a DTS demo Blu-ray disc coming next week that includes a 7.1 “DTS Sound Check” video. I’ll report back how the Arc handles the surround test tones from the 7.1 PCM signal.

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Not sure if this pertains to this conversation, but I just tested a 7.1.2 test tones video from my Dolby Atmos demo Blu-ray on my 5.1.2 Arc/Sub/Play:1s setup. The test tones for the left and right surround channels played perfectly clear out of my Play:1 rear surround speakers indicating that the Arc will take a 7.1 track and mix the two side surround channels into the two rear surround channels.

For Atmos, it doesn’t seem like there is a problem with the down conversion. The issue folks are having is with 5.1/7.1 content when Sonos is receiving a Multi-Channel PCM 7.1 signal. Given it was a Blueray, the signal was almost certainly not PCM. Anything using one of the Dolby codecs seem to work great (which Bluerays use).

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The sonos app reporting 7.1 multichannel, I thought was a bug with Sonos ARC?

All my devices that that should be 5.1 say 7.1 on the sonos app.

 

My xbox series x,  if set to uncompressed 5.1 outputs as multichannel 7.1 according to sonos app.

My oppo 203 is exactly the same.

As is my apple tv 4k for any 5.1 content that it sends as LPCM outputs as 7.1

 

Is Sonos still working on a fix, thought I read something a while back that they were aware?

Not for me at least. When I make a change to 5.1 on a device like the PS5, it updates instantly in the Sonos app to LPCM 5.1 from 7.1. My Apple TV 4K works correctly, outputting 5.1 LCPM on 5.1 media without any settings adjustments (even though more and more DD 5.1 content is being upgraded to Atmos, I couldn’t even find a 5.1 movie last night) I use that surround speaker test app which is known as a baseline.  When the Sonos app says 7.1, the sound is messed up and has gaps where the 2 extra speakers should be. The bug for me is the PS4/5 thinking the setup is 7.1 without manual intervention. Are you sure this isn’t a TV pass through issue? Try that surround speaker test app in DD5.1 and see what the Sonos app shows. 

Weird, perhaps it is my LG CX, I know others reported the same that have the CX as well.

Where can I find the speaker test app please?

In the Apple TV App Store: “surround speaker check”. In the app try the 5.1 speaker check. 

Userlevel 4
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The sonos app reporting 7.1 multichannel, I thought was a bug with Sonos ARC?

All my devices that that should be 5.1 say 7.1 on the sonos app.

 

My xbox series x,  if set to uncompressed 5.1 outputs as multichannel 7.1 according to sonos app.

My oppo 203 is exactly the same.

As is my apple tv 4k for any 5.1 content that it sends as LPCM outputs as 7.1

 

Is Sonos still working on a fix, thought I read something a while back that they were aware?

Not for me at least. When I make a change to 5.1 on a device like the PS5, it updates instantly in the Sonos app to LPCM 5.1 from 7.1. My Apple TV 4K works correctly, outputting 5.1 LCPM on 5.1 media without any settings adjustments (even though more and more DD 5.1 content is being upgraded to Atmos, I couldn’t even find a 5.1 movie last night) I use that surround speaker test app which is known as a baseline.  When the Sonos app says 7.1, the sound is messed up and has gaps where the 2 extra speakers should be. The bug for me is the PS4/5 thinking the setup is 7.1 without manual intervention. Are you sure this isn’t a TV pass through issue? Try that surround speaker test app in DD5.1 and see what the Sonos app shows. 

Weird, perhaps it is my LG CX, I know others reported the same that have the CX as well.

Where can I find the speaker test app please?

Userlevel 7

Not sure if this pertains to this conversation, but I just tested a 7.1.2 test tones video from my Dolby Atmos demo Blu-ray on my 5.1.2 Arc/Sub/Play:1s setup. The test tones for the left and right surround channels played perfectly clear out of my Play:1 rear surround speakers indicating that the Arc will take a 7.1 track and mix the two side surround channels into the two rear surround channels.

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The sonos app reporting 7.1 multichannel, I thought was a bug with Sonos ARC?

All my devices that that should be 5.1 say 7.1 on the sonos app.

 

My xbox series x,  if set to uncompressed 5.1 outputs as multichannel 7.1 according to sonos app.

My oppo 203 is exactly the same.

As is my apple tv 4k for any 5.1 content that it sends as LPCM outputs as 7.1

 

Is Sonos still working on a fix, thought I read something a while back that they were aware?

Not for me at least. When I make a change to 5.1 on a device like the PS5, it updates instantly in the Sonos app to LPCM 5.1 from 7.1. My Apple TV 4K works correctly, outputting 5.1 LCPM on 5.1 media without any settings adjustments (even though more and more DD 5.1 content is being upgraded to Atmos, I couldn’t even find a 5.1 movie last night) I use that surround speaker test app which is known as a baseline.  When the Sonos app says 7.1, the sound is messed up and has gaps where the 2 extra speakers should be. The bug for me is the PS4/5 thinking the setup is 7.1 without manual intervention. Are you sure this isn’t a TV pass through issue? Try that surround speaker test app in DD5.1 and see what the Sonos app shows. 

Userlevel 4
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The sonos app reporting 7.1 multichannel, I thought was a bug with Sonos ARC?

All my devices that that should be 5.1 say 7.1 on the sonos app.

 

My xbox series x,  if set to uncompressed 5.1 outputs as multichannel 7.1 according to sonos app.

My oppo 203 is exactly the same.

As is my apple tv 4k for any 5.1 content that it sends as LPCM outputs as 7.1

 

Is Sonos still working on a fix, thought I read something a while back that they were aware?

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Now the update is out for the Sonos Arc, I want to make sure I’m getting the best audio.

Playing Atmos content seems to work fantastic now. I am very happy with the sound from the Arc, Sub and 2 Ones.

When I play videos that have 5.1 audio, my Sonos app reports Multichannel PCM 7.1. Is this a problem as from what I understand my setup is not 7.1 (for reference, I am using an Apple TV 4K, LG GX, Sonos Arc, Sub and 2 Ones)?

Cheers.

I have the identical setup except for a Sony tv (HDMI 2.1). With my PS5, I have to manually force it to output 5.1. However, my AppleTV 4K recognized my 5.1.2 setup perfectly; Atmos, 5.1 etc. Download the AppleTV app “Surround Speaker Check” and run through the 5.1 test. Is your Sonos app showing LPCM 5.1? If it’s still showing 7.1, maybe it is the Apple TV? On Apple TV: settings - video and audio - audio format: is change format off and Dolby Atmos on? What video is showing up as 7.1 for you? I’ll test it on my setup. 

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This is how I’ve got it setup:

 

LG CX: HDMI in Bitstream (I tried PCM too, makes no difference since the passthrough on the audio out may make this selection irrelevant anyways?). EARC on. Audio Out passthrough.

 

PS4: HDMI audio. Linear PCM. 
 

Sonos app reports in getting Multichannel PCM 7.1. However it sounds off. Surround and certain environmental effects are very quiet but certain other sounds like dialogue or gunfire in a game right in front from center channel is very loud. It’s almost like it is missing certain channels or something. I’ve gone back to DD 5.1 which sounds great. Change PS4 output to Bitsream (Dolby) to get DD 5.1 which sounds much better balanced to me with the surround effect. 

Unless you have a genuine 7.1 setup (now even sure there is such a thing with Sonos) the PS4 is incorrectly identifying your 5.1.2 setup as 7.1 so you have dead spots in your sound field. The same thing happened to me. I swapped to DD on the PS4 and it correctly went to 5.1, like you said. Ran that until I got a PS5. On the PS5 if you set HDMI device type to TV Amplifier, you can force the PS5 to output 5.1 and LPCM sounds great. 

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That’s a negative on the PS5 sadly. If I select LPCM the PS5 will default to 7.1 and will not let me change the channel layout, it’s either Dolby Digital 5.1 or 7.1 LPCM

On the PS5: settings - sound - Audio Output - HDMI Device Type : AV Amplifier. This is the key setting. It will unlock the ability to set the number of channels to 5.1 and adjust speaker positions. With this setup, I am getting Linear PCM 5.1 with my Sonos 5.1.2 setup. For some reason the PS4 and PS5 interpret an Arc 5.1.2 setup as 7.1. Same number of channels perhaps? 

Userlevel 2
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Now the update is out for the Sonos Arc, I want to make sure I’m getting the best audio.

Playing Atmos content seems to work fantastic now. I am very happy with the sound from the Arc, Sub and 2 Ones.

When I play videos that have 5.1 audio, my Sonos app reports Multichannel PCM 7.1. Is this a problem as from what I understand my setup is not 7.1 (for reference, I am using an Apple TV 4K, LG GX, Sonos Arc, Sub and 2 Ones)?

Cheers.

I have the exact same setup and I am wondering the same. I use Infuse to play Blu-ray rips with DTS-HD streams. Infuse converts the audio to LPCM, but even a DTS-HD 5.1 stream is displayed as Linear PCM 7.1. I noticed the center channel (voice) is playing out of the rears when playing Ed Sheeran Jumping For Goalposts. Maybe something wrong with the channels?

Well that’s frustrating

Userlevel 4
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The Arc should be down-mixing 7.1 to 5.1 for non-Atmos streams that are actually sending 7.1 channels, and should be following the Atmos instructions for where Atmos streams.
I’m guessing that most things will have nothing on those side center channels though, so I’d think it should be fine.

 

It’s not - I’ve done some testing and the Arc is currently not downmixing

Userlevel 4
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Ah ok, if you only play games then LPCM is probably the way to go (there might be games with Dolby Atmos, but I’m not a big gamer myself anymore). I think the “let my receiver decode audio” is only for Bluray playback isn’t it? But I would disable that as well, if you only play games. 

 

Very few games support Atmos, but every game supports LPCM

The Arc should be down-mixing 7.1 to 5.1 for non-Atmos streams that are actually sending 7.1 channels, and should be following the Atmos instructions for where Atmos streams.
I’m guessing that most things will have nothing on those side center channels though, so I’d think it should be fine.

Userlevel 1
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Now the update is out for the Sonos Arc, I want to make sure I’m getting the best audio.

Playing Atmos content seems to work fantastic now. I am very happy with the sound from the Arc, Sub and 2 Ones.

When I play videos that have 5.1 audio, my Sonos app reports Multichannel PCM 7.1. Is this a problem as from what I understand my setup is not 7.1 (for reference, I am using an Apple TV 4K, LG GX, Sonos Arc, Sub and 2 Ones)?

Cheers.

Userlevel 4
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Ah ok, if you only play games then LPCM is probably the way to go (there might be games with Dolby Atmos, but I’m not a big gamer myself anymore). I think the “let my receiver decode audio” is only for Bluray playback isn’t it? But I would disable that as well, if you only play games. 

Not a clue I think I have always had it enabled, but I think it is just for the movies come to think of it.

Userlevel 3
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Ah ok, if you only play games then LPCM is probably the way to go (there might be games with Dolby Atmos, but I’m not a big gamer myself anymore). I think the “let my receiver decode audio” is only for Bluray playback isn’t it? But I would disable that as well, if you only play games. 

Userlevel 4
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Well, not sure about the “ofcourse”.

Bitstream means compression, LPCM 5.1 is uncompressed.

 

That’s not really correct. Bitstream means that the sound is not decoded and needs to be decoded by the audio system. This can be however uncompressed audio like DTS-HD or Dolby TrueHD. If you don’t want to lose Atmos, you need to use Bitstream on the XBox as Atmos metadata is not included in LPCM. For games though I would recommend to use LPCM to prevent any audio sync issues.

 

Im going to use LPCM 5.1 as I only play games, should I check “let my receiver decode audio” as well?

 

Thanks

Userlevel 3
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Well, not sure about the “ofcourse”.

Bitstream means compression, LPCM 5.1 is uncompressed.

 

That’s not really correct. Bitstream means that the sound is not decoded and needs to be decoded by the audio system. This can be however uncompressed audio like DTS-HD or Dolby TrueHD. If you don’t want to lose Atmos, you need to use Bitstream on the XBox as Atmos metadata is not included in LPCM. For games though I would recommend to use LPCM to prevent any audio sync issues.

Userlevel 4
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Don’t you long for the days when the only options for a coffee were black or white, and for audio formats Stereo or DD5.1?

lol, very much.

 

 

Don’t you long for the days when the only options for a coffee were black or white, and for audio formats Stereo or DD5.1?

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Well, not sure about the “ofcourse”.

Bitstream means compression, LPCM 5.1 is uncompressed.

 

I have been wondering the same, I only game on the xbox so thinking LPCM may be better, but LPCM 5,1 or 7.1 ?

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