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Apple TV 4K correct Audio Format for a Sonos Amp?

  • November 7, 2024
  • 8 replies
  • 703 views
T

I have an Apple TV 4K connected to a Samsung TV using an HDMI cable and then another HDMI cable using the Samsung’s HDMI Arc to connect to the Sonos Amp. My Sonos Amp has a KEF left and right channel as well as a subwoofer. I believe my Samsung TV audio settings are correct however I am not sure about the Apple TV 4K… Under Settings > Video and Audio > Audio Format, it defaults to LPCM. However, you have an option to change the format to either Dolby Digital 5.1 or Stereo. Seeing that the Apple TV 4K inputs to the Samsung TV and then uses an HDMI Arc cable to connect to the Sonos Amp, should I leave this setting to the default value of LPCM or should I set it to Dolby Digital or Stereo? 
 

Part of me thinks that this setting is irrelevant because whatever audio format is selected, it passes that value to the TV and in turn the TV passes the selected PCM audio format to the Sonos Amp but clearly not 100% sure. Thanks!

Best answer by Corry P

Hi @Thibaupe 

Welcome to the Sonos Community!

That is a good question, and your closing statement is not far off - how you go about it (which device you tell) is largely unimportant, but you do want to see Dolby Digital 5.1 reported in the Sonos app.

You can tell the Apple TV to do this (probably the easiest option), or the TV (if you set the TV to output Dolby Digital, then any input format should come out as such).

The Amp also supports DTS audio, which is superior to Dolby Digital - if you set the TV to output Dolby Digital, then you will never get DTS. Apple TV does not support DTS, so if you don’t use any other input devices, this is irrelevant. But, if you have a Blu-ray player connected to the TV, I recommend setting the TV’s output format to Passthrough and the Apple TV to Dolby Digital (though you may have to also instruct the Blu-ray to strip standard DTS out of any DTS-HD tracks (DTS-HD is unsupported by Sonos, but contains a standard DTS core within it that can be stripped out by some devices).

I do not recommend using any setting that says “stereo” - you’re just going to be limiting the experience.

I hope this helps.

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8 replies

Corry P
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  • Corry P
  • Sonos Staff
  • Answer
  • November 12, 2024

Hi @Thibaupe 

Welcome to the Sonos Community!

That is a good question, and your closing statement is not far off - how you go about it (which device you tell) is largely unimportant, but you do want to see Dolby Digital 5.1 reported in the Sonos app.

You can tell the Apple TV to do this (probably the easiest option), or the TV (if you set the TV to output Dolby Digital, then any input format should come out as such).

The Amp also supports DTS audio, which is superior to Dolby Digital - if you set the TV to output Dolby Digital, then you will never get DTS. Apple TV does not support DTS, so if you don’t use any other input devices, this is irrelevant. But, if you have a Blu-ray player connected to the TV, I recommend setting the TV’s output format to Passthrough and the Apple TV to Dolby Digital (though you may have to also instruct the Blu-ray to strip standard DTS out of any DTS-HD tracks (DTS-HD is unsupported by Sonos, but contains a standard DTS core within it that can be stripped out by some devices).

I do not recommend using any setting that says “stereo” - you’re just going to be limiting the experience.

I hope this helps.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
Airgetlam
I
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  • Ian_S
  • Prodigy III
  • November 12, 2024

You are in a bit of a bind potentially… 

LPCM surround is the best option for the Apple TV output, BUT, the TV can only pass multichannel PCM  over an eARC (not ARC) channel. The newer eARC standard supports lossless multichannel PCM which is what the Apple TV is trying to send. The Apple TV is doing the decoding of whatever the audio stream it’s playing into PCM, or can transcode into Dolby Digital if you select that. Dolby Digital is not lossless and won’t transmit stuff like Atmos. If the source audio the Apple TV is decoding is lossless, then PCM maintains the lossless audio. 

The TV itself will almost certainly accept a multichannel PCM signal over HDMI, as I think it’s a core format, however what it then does with that if it only has an ARC interface is less clear. It may down mix it to stereo. 

If multichannel PCM isn’t working from the Apple TV to the Sonos Amp, then it’s likely the TV is not eARC compatible. I don’t know if the Amp is, or needs to also be eARC capable to receive as well, I’m sure @Corry P can advise there. 

If you have issues with multichannel PCM from the Apple TV and aren’t getting surround to the Amp, then you may need to select Dolby Digital on the Apple TV, and make sure the TV is set to passthrough for the audio so it sends the DD signal the Apple TV has encoded to the Amp. 

 

Airgetlam
Corry P
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  • Corry P
  • Sonos Staff
  • November 12, 2024

Hi @Ian_S 

Amp does not support McLPCM, nor does it have an eARC socket. For Amp to play surround sound, the format must be either Dolby Digital, or DTS - no other surround formats are supported. PCM is supported, but that is only stereo. Atmos is not a consideration here.

If the Sonos device were an Arc, Arc Ultra or Beam Gen 2, McLPCM (and Atmos) would be supported over eARC (assuming the TV can support it). Atmos can also play over HDMI-ARC if encoded as Dolby Digital Plus, but Amp does not support it.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
controlav
Airgetlam
T
  • Thibaupe
  • Author
  • Contributor I
  • November 13, 2024

Thanks for all the great suggestions. The Samsung TV is an older model, we bought it around 2014 so when I went into the TV Menu > Sound > Addl Settings, The only two options to select are PCM or DTS Neo 2:5.  I see Dolby Digital, and DTS as other options but they are grayed out. When I selected DTS Neo. 2:5, DTS Surround 5.1 appears in the Sonos app, but the sound quality is poor with frequent gaps and pauses in the audio so I can’t use that setting.
 

I’m curious to know how I can enable Dolby Digital so that the TV can pass that onto the Sonos Amp? I see this more as a Samsung issue than a Sonos one but nonetheless curious to see if anyone has any advice on this issue… As it stands right now, putting the Samsung TV sound on PCM shows PCM stereo on the Sonos app which is not really ideal for movies. I might have to buy A newer TV, but I don’t see why they would give the options for Dolby Digital even if it is grayed out if there wasn’t a setting somewhere else that would allow you to select it. Thank you!!

 

 

Corry P
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  • Corry P
  • Sonos Staff
  • November 13, 2024

Hi @Thibaupe 

Often, a TV will only let you select a particular output format if that format is what is currently being inputted to the TV - if you play a Dolby Digital soundtrack before and while visiting that same setting page, you should be able to select Dolby Digital then.

I hope this helps.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
Airgetlam
Corry P
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  • Corry P
  • Sonos Staff
  • November 13, 2024

Hi @Thibaupe 

In addition, it looks like your TV is correctly determining that Amp will not play DTS:X and is stripping all but the DTS core from what it has and handing that core to the Amp to play. A reboot of the TV (unplug from power for a full minute) or a software update on the TV might help with the issues you’re hearing when playing DTS:X. This is mostly guesswork, by the way, so no guarantees.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein
Airgetlam
I
Forum|alt.badge.img+13
  • Ian_S
  • Prodigy III
  • November 13, 2024

What model of Samsung TV is it? You’re looking for an advanced setting that enables passthrough on audio over HDMI. DTS Neo 2:5 is ‘upmixing’ of 2 channel stereo to fake surround sound. It looks like Samsung were quite big into this, hence Sonos sees a DTS stream.

T
  • Thibaupe
  • Author
  • Contributor I
  • November 13, 2024

It’s a 2014 Samsung UN55H7150. 
 


 

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