Feature Request: Enable Dolby Digital Plus (E-AC-3 or DD+) for Better Audio Quality

  • 14 September 2018
  • 34 replies
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This feature request is for Sonos support Dolby Digital Plus, also known as E-AC-3 or DD+. This would permit a higher quality audio experience when watching surround sound-enabled videos.

Sonos currently supports PCM stereo and Dolby Digital (AC-3) surround sound. This made sense for the Playbar and Playbase, which only have a S/PDIF connection.

With the Sonos Beam's HDMI ARC connection, it is now possible to deliver a Dolby Digital Plus bitstream to the Sonos 5.1 system. Many Blu-rays include a 1.5Mbps Dolby Digital Plus track. Many streaming services including iTunes, Netflix, and Amazon Prime Video support the Dolby Digital Plus codec both for efficiency and in order to deliver Dolby Atmos. Further, it is possible for an app (like Plex) to transcode in a perceptually transparent manner from lossless codecs like TrueHD and DTS:X (as well as lossy codecs like DTS that are unsupported by Sonos) to Dolby Digital Plus. This is because DD+ can support up to 6Mbps throughput versus Dolby Digital's 640Kbps cap.

A simple software upgrade would deliver higher audio fidelity to systems with a Sonos Beam in a 5.1 arrangement (i.e. a Beam + 2x Sonos Ones + a SUB).

Note: this request is separate from delivering true home theater Dolby Atmos in a 7.1.4 speaker arrangement.


For more details:

https://developer.dolby.com/blog/dolby-audio-over-hdmi-part-1-codecs/

https://developer.dolby.com/blog/dolby-audio-over-hdmi-part-2-signaling-and-carriage/

https://developer.dolby.com/blog/dolby-audio-over-hdmi-part-3-reality/

https://developer.dolby.com/blog/dolby-audio-support-on-apple-tv/

https://www.avsforum.com/forum/39-networking-media-servers-content-streaming/2378442-dolby-digital-plus-dd-atmos-over-hdmi-arc.html

https://en.wikipedia.org/wiki/Dolby_Laboratories

34 replies

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Not sure how "a simple software upgrade" is going to make the audio hardware go from 640kbps to 6Mbps, which is an order of magnitude. If the hardware is grossly over-specced then this might be possible, but if it was designed for DD I don't see how a software upgrade is feasible.
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DD+ is backwards compatible with HDMI v1.3. Not sure whether the Beam has a v1.4 or 2.0x HDMI port but it must be at least v1.4 to support ARC.
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+1 on this. Huge disappointment that you cant get 5.1 sound out of devices like chromecast, fire stick, roku, etc as all are now play movies exclusively on dolby digital plus. sonos becoming worthless in home theater department without this feature
Userlevel 1
+1 this is absurd that you can’t use a Sonos beam to listen to Netflix, Hulu or Prime Video in 5.1 ; assume Sonos isn’t worried about this bc your average consumer doesn’t even realize they are getting sub par sound compared to what they could be getting. Shame on Sonos for not tackling this super obvious request that has been open for well over a year and supporting the format the worlds most common streaming platforms have been using for years!
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I can't speak to all device edge cases but if your STB or your TV has a DD+ (E-AC-3) decoder, then it _can_ extract a DD (AC-3) legacy substream. However...

- Because the Sonos Beam doesn't appear to support DD+, Sonos needs an upstream device to extract DD from DD+.

- This introduces both hardware decoder and user configuration dependencies.

- Extraction of DD from the DD+ audio stream will result in lower audio fidelity as compared to DD+.

- Frequently, there is the possibility of a device in the HDMI chain defaulting to 2.0 PCM rather than 5.1 surround sound.


Beyond that, if your source audio is very high quality, such as lossless audio, then DD+ is the best means to replicate TrueHD, DTS-X, etc. in a perceptually transparent manner--unless and until Sonos _and_ your TV manufacturer support E-ARC.

- For now, Sonos could take advantage of up to 6.1 Mbps to render lossy 5.1 or 7.1 audio in DD+.

- Long term, Sonos may be able to retrofit eARC on the Beam for lossless audio (Dolby MAT 2.0+ is already supported by the Apple TV 4K).
Any update on this point ? I face the same issue, getting only stereo on Netflix using a BEAM, SUB et 2 play 1
The BEAM sound bar is not an old one and the price must justify an update to fit the main streaming application that is Netflix
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My "old" Playbar can do DD 5.1 from Netflix, call me skeptical that a Beam cannot do the same. Sounds like some kind of config issue to me.
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My "old" Playbar can do DD 5.1 from Netflix, call me skeptical that a Beam cannot do the same. Sounds like some kind of config issue to me.

My setup with Playbar + 2x One + Sub get perfect DD 5.1 from Netflix, iTunes, Viaplay with no issues at all. ATV 4K connected to Samsung 7 series TV with HDMI 1.3 cable and optical from TV to Playbar. No issues.
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Any update on this point ? I face the same issue, getting only stereo on Netflix using a BEAM, SUB et 2 play 1
The BEAM sound bar is not an old one and the price must justify an update to fit the main streaming application that is Netflix


Netflix DD5.1 titles will play on a Sonos 5.1 system, with all discrete channels preserved routed properly.

DD+ will get remixed, extracted, or otherwise reprocessed so it will play back to the utmost on the Sonos 5.1 system (as MikeConnelly said)

Those above who said they cant use 5.1, they're mistaken. In your case, it's something in your setup/config that needs to be tweaked
Now that Google assistant is about to be lunched I don't see any better feature to be added than DD+ support.
@MikeConnelly congrats for the initiative and this so well described request.

Agreed 100%, Dolby Digital Plus is getting more and more common and if Sonos wants to play in the Home cinema/surround league has to support at least DD+. In my opinion should also support DTS, DTS HD and Dolby TrueHD (at least the beam) but guess I could live without it if DD+ is supported. DD+ conversion to DD is okay for now but quality will be lost at least for the higher bit rates, therefore not acceptable for the standards that Sonos got us used to.

My surround speakers (two ones) + sub purchase is frozen because of this. Will be waiting for it. 😃


Those above who said they cant use 5.1, they're mistaken. In your case, it's something in your setup/config that needs to be tweaked


Not true at all. My Samsung television can support Dolby Digital Plus. It has a Dolby M11 chipset which handles Dolby Digital Plus signals. I'm setup to send Bitstream data to the Beam over HDMI. The ARC connection for the Beam however only states it can support PCM stereo and Dolby Digital (not plus). When my Roku is the source device it is detecting that I can do Stereo and Dolby Digital (again not plus) in its Audio menu. Netflix app sees this and only offers me the stereo audio track as it only uses Dolby Digital Plus to send any Dolby Digital broadcasts. If I manually set the Roku's Audio setting that I support Dolby Digital Plus, when I start Netflix I can now pick the stereo or Dolby Digital track. However selecting the Dolby Digital track produces zero sound out to the Beam. My television doesn't even give me the option to send Dolby Digital in this case over the Bitstream connection. It is only offers PCM stereo or DTS Neo, of which the Beam can only handle the PCM stereo. Therefore the television is refusing to do any transcoding of the signal either. As the Beam doesn't support the Dolby Digital Plus audio, I get no sound.

This is why people are asking that Dolby Digital Plus be included on the Beam as one of the formats it can handle. This should effectively allow streaming devices that cannot convert the Dolby Digital Plus signal to a straight Dolby Digital mix to be able to hear something more than stereo. More and more streaming apps are switching to Dolby Digital Plus because it can be compressed better than just Dolby Digital and they will just allow something further down the chain to handle pulling the Dolby Digital mix out of it. I'd rather my Beam just get that audio and handle extracting whatever version of Dolby Digital they want to support from that stream.
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DD+ is backwards compatible with HDMI v1.3. Not sure whether the Beam has a v1.4 or 2.0x HDMI port but it must be at least v1.4 to support ARC. HDMI version has zero to do with bitstream decoding capabilities of the DSP in the speaker.
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I can't speak to all device edge cases but if your STB or your TV has a DD+ (E-AC-3) decoder, then it _can_ extract a DD (AC-3) legacy substream. However...

- Because the Sonos Beam doesn't appear to support DD+, Sonos needs an upstream device to extract DD from DD+.

- This introduces both hardware decoder and user configuration dependencies.

- Extraction of DD from the DD+ audio stream will result in lower audio fidelity as compared to DD+.

- Frequently, there is the possibility of a device in the HDMI chain defaulting to 2.0 PCM rather than 5.1 surround sound.


Beyond that, if your source audio is very high quality, such as lossless audio, then DD+ is the best means to replicate TrueHD, DTS-X, etc. in a perceptually transparent manner--unless and until Sonos _and_ your TV manufacturer support E-ARC.

- For now, Sonos could take advantage of up to 6.1 Mbps to render lossy 5.1 or 7.1 audio in DD+.

- Long term, Sonos may be able to retrofit eARC on the Beam for lossless audio (Dolby MAT 2.0+ is already supported by the Apple TV 4K).


Wont happen. It's hardware that's required. It's not physically possible to change for either eARC or DD+. The beam is forever stuck as it is until they release a new product.

HDMI connected devices use EDID to communicate to each other at the time of connection. In this communication, the devices establish with each other what their respective capabilities are and how it will be sent. Hence, the Beam merely says to the TV, "Mr. TV, please send DD or PCM 2.0 as that's all I can support"

If you have selected Optical for your output, the TV merely sends PCM 2.0 or DD by default as it know's that's the most that method can support.

Depending on the output settings of the sending device (the tv), the beam will get either DD bitstream or PCM stereo. This is always an end user option in the audio output menu's of the TV. It's literally the exact same SPDIF stream that is output whether its through the optical connector or the HDMI connector. It's merely just a matter of what hole in the tv you want that stream to come out of.

When a DD+ encoded content is available and the connected device doesn't support it (or the selected output method of the TV for example doesnt support it - i.e. optical or ARC connected), it merely converts the DD+ bitstream to the DD substream that is packed within it. And that small conversion (it does not transcode the audio, it merely changes the format of the stream) is 100% mandatory per Dolby requirements. You cannot have DD+ without DD. It's not physically possible and any obstruction of that would find a manufacturer in a courtroom quite quickly being violated 10 ways by a gaggle of Dolby lawyers.

The truth is..and Sonos knows this...There's not a human alive that would hear or could identify, in a blind audio test or otherwise, the difference between Dolby Digital Plus and Dolby Digital through the Beam's small drivers.

eARC also requires new hardware as it's an entirely different physical path than legacy ARC for the audio between eARC compatible devices.
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Those above who said they cant use 5.1, they're mistaken. In your case, it's something in your setup/config that needs to be tweaked


It has a Dolby M11 chipset which handles Dolby Digital Plus signals.

Dolby does not manufacture IC's. Doesn't mean your Samsung doesn't support DDP, it just means you whatever chipset Samsung uses contains the MS11 decoder


I'm setup to send Bitstream data to the Beam over HDMI. The ARC connection for the Beam however only states it can support PCM stereo and Dolby Digital (not plus).

It's not the Beam. Optical and ARC support Dolby Digital (most all TV decode and pass it through), DTS 5.1 (Some TV's can pass it/decode it, some cant), and PCM 2.0. Regardless, in bitstream format it is the exact same SPDIF stream output through both connectors. It's merely based on what output you tell the TV to send it to. Your TV should merely be passing the bitstream audio it gets from the Roku through to the Beam and not decoding it unless you select PCM out, which it will then do a transcode and mixdown to 2.0 PCM and send that to the Beam. Your Roku is getting it's data from the TV as to what it supports audio wise based on whatever settings you are using.

1. ARC - Roku should only send Bitstream DD or PCM 2.0
2. Optical - Roku should only send Bitstream DD or PCM 2.0
3. HDMI - Roku should send whatever the highest quality audio is that the device can support based on its settings



When my Roku is the source device it is detecting that I can do Stereo and Dolby Digital (again not plus) in its Audio menu.

This is correct behavior. It has learned through the HDMI connection to the TV that the TV can only use DD and PCM 2.0 due to your ARC connection. It should NEVER say DDplus. ARC and Optical cannot physically support the bandwidth required to pass DDP or mroe than 2 channels of uncompressed audio.

Netflix app sees this and only offers me the stereo audio track as it only uses Dolby Digital Plus to send any Dolby Digital broadcasts.

Dolby Digital is a substream of Dolby Digital Plus and you cannot physically have one without the other as DD literally exists within the DDP bitstream. This sounds like failure in the app. I'll repeat from my earlier response above "When a DD+ encoded content is available and the connected device doesn't support it (or the selected output method of the TV for example doesnt support it - i.e. optical or ARC connected), it merely converts the DD+ bitstream to the DD substream that is packed within it. And that small conversion (it does not transcode the audio, it merely changes the format of the stream) is 100% mandatory per Dolby requirements. You cannot have DD+ without DD. It's not physically possible and any wilful and intentional obstruction of that would find a manufacturer in a courtroom quite quickly being violated 10 ways by a gaggle of Dolby lawyers and likely get the license pulled if not remedied. "

If I manually set the Roku's Audio setting that I support Dolby Digital Plus when I start Netflix I can now pick the stereo or Dolby Digital track. However selecting the Dolby Digital track produces zero sound out to the Beam.

This is seemingly correct behavior. It's likely you are telling the ROKU to ignore the data has received via EDID from the TV and send a DDP stream anyways. The TV merely passes that DDP bitstream to the Beam and you get silence. Thus, because your TV knows the limitations of the Beam, all it will do is allow you to send out PCM 2.0 Stereo. Again, this appears to be a failure in the Netflix app in how it is handling the Dolby audio stream.

My television doesn't even give me the option to send Dolby Digital in this case over the Bitstream connection.

Nope, because it knows the Beam doesnt support DDP and the Netflix app appears to be failing to properly deal with Dolby audio, but you've told the ROKU to force DDP

It is only offers PCM stereo or DTS Neo, of which the Beam can only handle the PCM stereo. Therefore the television is refusing to do any transcoding of the signal either.

The TV would not transcode the Dolby stream unless you've told it to sent PCM out. There is no transcode process between DDP and DD


As the Beam doesn't support the Dolby Digital Plus audio, I get no sound.

Yes, you've told the Roku to send it, the Netflix app is failing to handle that properly, and you're getting a DDP stream that has not been converted to DD. You might as well be sending DTS :D

This is why people are asking that Dolby Digital Plus be included on the Beam as one of the formats it can handle.

Won't happen. Not physically possible.


This should effectively allow streaming devices that cannot convert the Dolby Digital Plus signal to a straight Dolby Digital mix to be able to hear something more than stereo. More and more streaming apps are switching to Dolby Digital Plus because it can be compressed better than just Dolby Digital and they will just allow something further down the chain to handle pulling the Dolby Digital mix out of it.

I'd rather my Beam just get that audio and handle extracting whatever version of Dolby Digital they want to support from that stream.

That is exactly what is happening. But Netflix appears to be failing and you are sending an unconverted DDP bitstream to the Beam, but it can't pull the mix out of something it cant decode. Its like trying to speak Chinese to a German in Greece.

What happens when you use optical? What happens when you use other DDP encoded content from another app?


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DD+ is backwards compatible with HDMI v1.3. Not sure whether the Beam has a v1.4 or 2.0x HDMI port but it must be at least v1.4 to support ARC. HDMI version has zero to do with bitstream decoding capabilities of the DSP in the speaker.

The original question and my response concerned requisite bandwidth, not where audio was decoded. My point was that even HDMI v1.3 enabled sufficient bandwidth to support DD+.

DSPs can be upgraded, particularly if they are media decoders within a SoC. Sonos' job board even has listings for audio DSP engineers.

The truth is..and Sonos knows this...There's not a human alive that would hear or could identify, in a blind audio test or otherwise, the difference between Dolby Digital Plus and Dolby Digital through the Beam's small drivers.

I can easily hear the difference between lossy (e.g. 256kbps AAC) and lossless (e.g. ALAC) audio on my Sonos systems. Legacy Dolby Digital is even lower quality than AAC on a bit-for-bit basis. Moreover, legacy DD is lower bitrate per channel because 5.1-ch Dolby Digital audio is typically encoded at bitrates between 384-640 kbps.

Which brings me back to my original point: until eARC arrives--and is implemented in every device within a consumers' home theater system--most consumers are stuck with ARC for the foreseeable future. But, even with ARC, it is technically possible to support higher fidelity audio than legacy DD. Sonos need not support TrueHD or DTS:X or 5.1 PCM to render DD+ audio that is perceptually transparent to these lossless codecs. And, DD+ will better showcase the existing audio quality of Sonos' speakers similar to how Sonos speakers sound better playing stereo PCM or ALAC than AAC or legacy DD.
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DD+ is backwards compatible with HDMI v1.3. Not sure whether the Beam has a v1.4 or 2.0x HDMI port but it must be at least v1.4 to support ARC. HDMI version has zero to do with bitstream decoding capabilities of the DSP in the speaker.

The original question and my response concerned requisite bandwidth, not where audio was decoded. My point was that even HDMI v1.3 enabled sufficient bandwidth to support DD+.

DSPs can be upgraded, particularly if they are media decoders within a SoC. Sonos' job board even has listings for audio DSP engineers.

Your post is focused on the beam. So your argument makes no sense at all. Yes, HDMI 1.3 can support Dolby Digital Plus but it doesn't support ARC and is completely irrelevant topically. There isnt enough bandwidth available via SPDIF or ARC (which is the exact same audio stream). The Beam is an audio receiver only and it receives that audio in a very defined way. The only reason it has an HDMI transmitter at all is to meet HDMI specifications which require video to be generated and use of the TMDS clocks, hence the pattern you get on your TV when you turn the input to where the Beam is connected. As such, it can only receive audio from the TV, and with ARC there's only 3 flavors of it, Dolby Digital, DTS 5.1 (in most tv's in the last few years), and PCM stereo. So, why on earth would Sonos support DD+ when it is technology that it cannot physically use and no device on the planet will send it, and then pay a royalty for it to boot?

As far as your upgrade argument, you need to understand the difference between ROM and RAM based DSP's. A job listing for a DSP engineer means nothing towards your argument. All Sonos products use a DSP regardless of what the decoding capabilities are, including the Play One which cant decode any type of dolby or dts bitstream audio. Secondarily, in order to support eARC, you need a hardware based solution. It's not physically possible to do it any other way.

The bottom line is this. It is physically impossible for the current beam to support Dolby Digital Plus, much less any other Sonos product, period. It cannot physically happen without the release of a "Beam 2" or new hardware entirely.


The truth is..and Sonos knows this...There's not a human alive that would hear or could identify, in a blind audio test or otherwise, the difference between Dolby Digital Plus and Dolby Digital through the Beam's small drivers.

I can easily hear the difference between lossy (e.g. 256kbps AAC) and lossless (e.g. ALAC) audio on my Sonos systems. Legacy Dolby Digital is even lower quality than AAC on a bit-for-bit basis. Moreover, legacy DD is lower bitrate per channel because 5.1-ch Dolby Digital audio is typically encoded at bitrates between 384-640 kbps.

There's a huge difference between lossless ALAC and 256 AAC. Matter of fact , they are so miles apart it's a bit of a silly statement. From compression algorithms to efficiency it's an apples to oranges comparison. However, DD+ and DD with Dolby's encoding algorithms are much closer in many ways and much more efficiently encoded. It's not always about bitrate, its about efficiency. Dolby does a fantastic job of efficiently encoding audio streams at some pretty low bitrates. It's not too far from the joker that thinks because Sony sticks 1000 WATTS on their AVR, that it's actually 1000 WATTS and that makes it bigger, better, louder when it's simply bullshit marketing. Yes, bandwidth contributes to many factors, but it's by no means the magic bullet. And no, you cannot hear the difference on a 3" sonos beam driver or playbar, play one driver etc between the two, especially streamed via Netflix etc. Sorry. You might think you can, but you're arguing against much more than you realize is going on with how they do their signal processing and the DD+ stream you are getting.

Which brings me back to my original point: until eARC arrives--and is implemented in every device within a consumers' home theater system--most consumers are stuck with ARC for the foreseeable future. But, even with ARC, it is technically possible to support higher fidelity audio than legacy DD.

No, you are not stuck with ARC when you step outside of Sonos' environment. There's 24/bit 96 Khz wireless multi-channel audio solutions from 800 bucks for a full 5.1 up to 40,000 a speaker that support up to 8 channels of completely uncompressed video and all flavors in between, and they dont rely on your home wifi to do it (which would fail miserably and never pass Dolby/DTS certification).. And no, it's not technically possible to pass any higher fidelity multi-channel audio via ARC, that's just a blatant untruth. If it were true, every manufacturer out there would be doing it and there's a reason they aren't.


Sonos need not support TrueHD or DTS:X or 5.1 PCM to render DD+ audio that is perceptually transparent to these lossless codecs. And, DD+ will better showcase the existing audio quality of Sonos' speakers similar to how Sonos speakers sound better playing stereo PCM or ALAC than AAC or legacy DD.


As far as anything outside of DD+/Atmos, physical media (which is the only place you can get True, DTS X or 5.1 PCM) is vaporizing and being eliminated from the market as we speak. Hence, Sonos understands very well that it makes ZERO business sense to adopt those codecs, especially at the license/royalty rates being charged per product. Sonos needs to support DD+ because it's what the consumers expect and it's where streaming is establishing its audio base. But in order to do that, they need to implement the technology that can support it, which they have shown no signs of doing. In order to do this, they would need to turn their product into an HDMI repeater or add an eARC hardware solution..there's NO other option. However, when you go into being an HDMI repeater, you now step out of audio and into the Video realm and all the specifications that HDMI LA requires in order to be a licensed product. Sonos home theater category is not the driving force behind the company, being a whole house audio solution is. That being said, it would appear that the only way you are getting anything higher than Dolby Digital or stereo PCM would be a nextgen product that would support eARC as there's a much higher possibility that would occur long before they would start getting into the video side of HDMI. And we're years away from a household eARC ecosystem.

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Let's keep it simple:

[b]Your post is focused on the beam. So your argument makes no sense at all. Yes, HDMI 1.3 can support Dolby Digital Plus but it doesn't support ARC and is completely irrelevant topically. There isnt enough bandwidth available via SPDIF or ARC (which is the exact same audio stream).

Incorrect.

See https://www.avsforum.com/forum/39-networking-media-servers-content-streaming/2378442-dolby-digital-plus-dd-atmos-over-hdmi-arc.html

[b]and with ARC there's only 3 flavors of it, Dolby Digital, DTS 5.1 (in most tv's in the last few years), and PCM stereo.

Incorrect.

[b]Secondarily, in order to support eARC, you need a hardware based solution. It's not physically possible to do it any other way.

Off topic. My focus is ARC, not eARC.

It is physically impossible for the current beam to support Dolby Digital Plus, much less any other Sonos product, period. It cannot physically happen without the release of a "Beam 2" or new hardware entirely.

Incorrect.

No, you cannot hear the difference on a 3" sonos beam driver or playbar, play one driver etc between the two, especially streamed via Netflix etc. Sorry. You might think you can, but you're arguing against much more than you realize is going on with how they do their signal processing and the DD+ stream you are getting.]

Incorrect.
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Let's keep it simple:

[b]Your post is focused on the beam. So your argument makes no sense at all. Yes, HDMI 1.3 can support Dolby Digital Plus but it doesn't support ARC and is completely irrelevant topically. There isnt enough bandwidth available via SPDIF or ARC (which is the exact same audio stream).

Incorrect.

See https://www.avsforum.com/forum/39-networking-media-servers-content-streaming/2378442-dolby-digital-plus-dd-atmos-over-hdmi-arc.html

[b]and with ARC there's only 3 flavors of it, Dolby Digital, DTS 5.1 (in most tv's in the last few years), and PCM stereo.

Incorrect.

[b]Secondarily, in order to support eARC, you need a hardware based solution. It's not physically possible to do it any other way.

Off topic. My focus is ARC, not eARC.

It is physically impossible for the current beam to support Dolby Digital Plus, much less any other Sonos product, period. It cannot physically happen without the release of a "Beam 2" or new hardware entirely.

Incorrect.

No, you cannot hear the difference on a 3" sonos beam driver or playbar, play one driver etc between the two, especially streamed via Netflix etc. Sorry. You might think you can, but you're arguing against much more than you realize is going on with how they do their signal processing and the DD+ stream you are getting.]

Incorrect.


Whatever you say there champ, not going to enterain silliness. Bottom line. You arent getting DD+ in a Sonos product without new hardware. It's a fact, it's provable, and already been proven. Go spend the money, crack one open and take a look inside, it's staring you in the face. You just aren't aware. And unless you build this type of product for a living (which it's clear you don't), it's not expected that you would know this.

Just a hot tip for you:

In re: ARC/DD+, good luck. I'd love to see what an HDMI analyzer tells you that you are actually getting in that DD+ stream. You might be a bit surprised. I'll tell you this juicy lil tidbit, it's obvious you didn't know that the ARC bitrate is capped at 1Mbps, which is a VERY low bitrate DD+ stream. DD+ reaches 6Mbps, and as such ARC DOES NOT SUPPORT IT...you're getting a marginally better stream than legacy DD encoded a bit more efficiently to the extent it can with any additional allocated bits (which isnt a whole lot down that low). So if you want to claim it's supported because it will give you a stream with a DD+ EDID report that is literally encoded slightly more efficiently with an additional 360Kbps across 6 channels of audio vs. legacy DD, feel free to kid yourself (which isn't even what occurs with the additional bitrate anyways in a literal sense). But hey, if you can hear the sub 1Mbps efficiency improvement to the compression schema via an ARC connection on a 3" driver ...I'd love to hire you to come in and work on my staff as none of my 30 year acoustical engineers can do it, nor can an analyzer. When you learn how those extra bits are allocated, you'll probably feel sillier, but I'll just stop there.

So, you can convince yourself that you can hear 360Kbps of glorious audio bliss and massive improvement between DD and DD+ all you want, but the way the compression scheme works and bitstream is handled, it's pretty funny to see you try. But you do you boo. WIth 93% of the panels in the market not supporting DD+ via ARC and a fraction of AVR's out there doing it, you get 3 flavors chief...DD, DTS 5.1 and Stereo PCM ..and if you're foolish enough to think that DD+ is going to matter...well, can't help you chief. 😃
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From the documents linked in my first post:

"The 3 main clock rates that are important for Dolby codecs are 48 kHz, 192 kHz and 768 kHz. The data pipe is 2 channels with 16 bits per channel, so when you multiply the pipe size and the clock rate, you correspondingly get 1.5 Mbps, 6 Mbps, and 24.5 Mbps."

“The key difference between HDMI ARC and the HDMI forward channel is how much data can be transmitted - ARC only supports the 48 kHz and 192 kHz clock rates which means that Dolby Digital and Dolby Digital Plus are supported but Dolby TrueHD is not supported as there isn't enough bandwidth.”

"Before 2016, televisions only supported Dolby Digital over HDMI ARC and haven’t been upgraded to support Dolby Digital Plus passthrough. However, most recent televisions now support Dolby Digital Plus over HDMI ARC." My earlier post linked to a list of 2016-17 TVs known to either passthrough or transcode audio to DD+. It also included a number of competitors' soundbars known to support DD+ via ARC. Generally speaking, it can be assumed that Atmos soundbars and AVRs support DD+ over ARC.

Regarding sound quality:

“5.1-ch Dolby Digital audio is typically encoded at bitrates between 384-640 kbps”. Prior to proposing this feature in my first post, I ran a number of tests, using FFMPEG to convert Dolby TrueHD, DTS-HD Master Audio, and PCM sources to E-AC3 at a variety of bitrates to determine what was perceptually transparent to my ears. Clearly, E-AC3 is not only more efficient than AC3 but has better resultant audio quality. Moreover, the Dolby E-AC3 encoder reportedly is better than FFMPEG's E-AC3 encoder.

All five of my Sonos Beams are deployed either as 5.0 or 5.1 systems (paired with Sonos Ones and SUBs).

Finally, to correct another error: the lower the bitrate, the greater the audio compression, the greater the potential audio artifacts. Thus, even marginal improvements of available bandwidth in bandwidth constrained scenarios can result in a significant improvement in perceptual audio quality and reduction of audio artifacts.
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From the documents linked in my first post:

"The 3 main clock rates that are important for Dolby codecs are 48 kHz, 192 kHz and 768 kHz. The data pipe is 2 channels with 16 bits per channel, so when you multiply the pipe size and the clock rate, you correspondingly get 1.5 Mbps, 6 Mbps, and 24.5 Mbps."

“The key difference between HDMI ARC and the HDMI forward channel is how much data can be transmitted - ARC only supports the 48 kHz and 192 kHz clock rates which means that Dolby Digital and Dolby Digital Plus are supported but Dolby TrueHD is not supported as there isn't enough bandwidth.”

"Before 2016, televisions only supported Dolby Digital over HDMI ARC and haven’t been upgraded to support Dolby Digital Plus passthrough. However, most recent televisions now support Dolby Digital Plus over HDMI ARC." My earlier post linked to a list of 2016-17 TVs known to either passthrough or transcode audio to DD+. It also included a number of competitors' soundbars known to support DD+ via ARC. Generally speaking, it can be assumed that Atmos soundbars and AVRs support DD+ over ARC.

Regarding sound quality:

“5.1-ch Dolby Digital audio is typically encoded at bitrates between 384-640 kbps”. Prior to proposing this feature in my first post, I ran a number of tests, using FFMPEG to convert Dolby TrueHD, DTS-HD Master Audio, and PCM sources to E-AC3 at a variety of bitrates to determine what was perceptually transparent to my ears. Clearly, E-AC3 is not only more efficient than AC3 but has better resultant audio quality. Moreover, the Dolby E-AC3 encoder reportedly is better than FFMPEG's E-AC3 encoder.

All five of my Sonos Beams are deployed either as 5.0 or 5.1 systems (paired with Sonos Ones and SUBs).

Finally, to correct another error: the lower the bitrate, the greater the audio compression, the greater the potential audio artifacts. Thus, even marginal improvements of available bandwidth in bandwidth constrained scenarios can result in a significant improvement in perceptual audio quality and reduction of audio artifacts.


Sigh. You can cut and paste all you like, you fail to understand much of it. You comparing FFMPEG compression to Dolby's compression schema as an E-AC3 test gave me a chuckle, as it would any engineer familiar with Dolby's processes. Go talk to a Dolby engineer about that one, he'll laugh too. Or , you can talk to any of us who have been engineering consumer audio products for decades. Response will be the same. You're not teaching anyone anything here about compression, I assure you. Likelihood is my work has been in your living room at some point, if not currently.

So listen, if you want to run around patting yourself on the back that you can hear the difference of a marginal (and I mean MARGINAL) bitrate and efficiency difference you are getting as DD+ vs DD via ARC, go ahead. ARC is limited to 1Mpbs. DD+ tops at 6Mbps. But hey, it's only all layers of 5Mpbs in between the two. Nothing major. And this is where your lack of understanding of how Dolby's compression schema ACTUALLY works, is glaring.

While I'm the one that informed you about efficiency vs bitrate, the DD+ compression schema at that bitrate offers LITTLE to gain in regards to human auditory perception (or tangible improvements that can be picked up by hardware). Step up the bitrate some, and that's where you start to see performance that the human ear can readily distinguish and it's what some would call "cruising speed" for the DD+ compression schema. You may not want to concede this with your 5 Sonos systems in tow, but the hard fact is that when you pour the sauce on the audio that Sonos does through their own "signature" signal processing through their DSP and then pipes it out a 3" driver, its quite a bit different than the source audio it was given. As it relates to DD+, factually speaking, only a scope can give you a glimpse of a few visible, yet very minor, differences when you are down that low in bit rate. Sorry to burst your bubble and the placebo you are taking to convince yourself you can.

Bottom line. True support as defined by the engineering community and by technical specifications in an implementation that allows for the entirety of a particular technology, not a sliver of it. In the marketing community however, it's entirely different, and you are drinking the Kool Aid big time. Let's go back to that Wattage/AVR thing again. The box will tell you your precious AVR is 1000 watts, the engineer and specification says something ENTIRELY different. It's marketing. What they arent saying to you is, "Well, we only offer the lowest common denominator of it". That's not going to sell many products.

ARC DOES support DD and DTS 5.1 as it offers the ENTIRETY of the technology. It's up to a manufacturer however, if they choose to pass through a particular bitstream type at all. (aka no DTS support)

Let me ask you a glaringly obvious question you clearly are missing. Why do you think the massively different structure of eARC is here? Why would the community create and technology evolve in such a way it if all you needed was ARC, DD+ w/ MAT (for Atmos), and a Sonos Beam for example? Ill let you ponder on that one. Go ahead, argue TrueHD/Master Audio. It'll make you feel better. Find something to cut and paste...I get it.

Nonetheless, this is all completely irrelevant to the fact of your post. Sonos cannot, in ANY of its current hardware, support Dolby Digital Plus, in any capacity. Period. Why do you think it is that they don't? If its a simple firmware update, why hasnt it happened in generations of their products? DD+ is over a decade old. It's new hardware that's needed. I'll end this silliness there.
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DD+ or E-AC3 is a published format (Annex E of ATSC A/52:2012). FFMPEG produces compliant E-AC3 encodes (currently limited to 5.1 channels with no Atmos object transcoding). A number of apps with millions of users (Plex, Kodi, Infuse, MrMC, etc.) leverage FFMPEG. For example, Plex transcodes lossless audio to E-AC3 by default. That is why I used it for testing. As discussed earlier, Dolby's encoder is reportedly best of breed.

I transcoded a number of audio segments to E-AC3. To my ears, E-AC3--somewhere between 2.5-3Mbps--is perceptually transparent to lossless audio tracks such as LPCM, TrueHD or DTS-HD Master Audio (depending on the audio segment). We await your test results.

You continually say that ARC is limited to 1Mbps while DD+ tops at 6Mbps. But, your assessment necessarily is based on a 48 kHz clock rate (which is closer to 1.5Mbps). To reaffirm my earlier math: at a 192 kHz clock rate, you get 6.1 Mbps. Moreover, all the major CE manufacturers (e.g. Samsung, LG, Sony, etc.) have Dolby Atmos soundbars that support E-AC3 over ARC. So, it's not clear why you are arguing against the possiblity of E-AC3 over ARC.

I don't have the time or desire to deconstruct my new Sonos Beams but there are publicly available teardowns of the Sonos One. These report that the SoC is a Freescale NXP SoM SC667517EYM10AE. This is more than capable of decoding E-AC3. See: https://medium.com/@BenEinstein/what-cracking-open-a-sonos-one-tells-us-about-the-sonos-ipo-dcab49155643
I would be surprised if the Sonos Beam is significantly different from the Sonos One, architecturally.

Sonos couldn't do this in earlier iterations of their speakers because:
(1) the Playbar and Playbase were limited to an optical audio connection (not HDMI ARC), and
(2) the earlier generation of Sonos speakers had processors that were, by Sonos' reporting, 1/16 as powerful as current generation of speakers.

Addressing what the advantage of eARC over ARC is:
* support for lossless codecs like TrueHD or Dolby MAT 2.0 up to 38 Mbps, and
* there is also better service discovery and better lip sync.

Finally, my goal is to improve Sonos' Beam/AMP/One product lines. I have invested $$,$$$ in my Sonos equipment. My focus is improving the sound quality for the systems that I have purchased. I commend how Sonos has continued to improve Sonos spears that are 10-15 years old.

What is your Sonos $ investment and objectives?
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Dear lord. Enjoy your Sonos. You really have no clue what you're talking about and make an astronomical amount of assumptions as it relates to the topic. Peace out.
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🆒 ARC= 1Mbps. Don't forget.
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Rut roh....

along with the Keyword

You should have noticed these when you were cutting and pasting "your math" from the Dolby dev site.

Since you don't have access to the same Dolby information as us engineers who do this for a living do.....




And since you like being links and are clearly an educated audiophile: https://www.nakamichi-usa.com/best-dolby-atmos

Atmos = TrueHD or DD, in case you forgot.

Might give you a clue about a few other things if that doesnt make it obvious for you.

I'm sure the actual investors (as in the stockholders) are quite excited at the proposition that you will need to invest further in order to realize your feature addition dreams. Nite nite.

n re: ARC/DD+, good luck. I'd love to see what an HDMI analyzer tells you that you are actually getting in that DD+ stream. You might be a bit surprised. I'll tell you this juicy lil tidbit, it's obvious you didn't know that the ARC bitrate is capped at 1Mbps, which is a VERY low bitrate DD+ stream. DD+ reaches 6Mbps, and as such ARC DOES NOT SUPPORT IT...you're getting a marginally better stream than legacy DD encoded a bit more efficiently to the extent it can with any additional allocated bits (which isnt a whole lot down that low). So if you want to claim it's supported because it will give you a stream with a DD+ EDID report that is literally encoded slightly more efficiently with an additional 360Kbps across 6 channels of audio vs. legacy DD, feel free to kid yourself (which isn't even what occurs with the additional bitrate anyways in a literal sense). But hey, if you can hear the sub 1Mbps efficiency improvement to the compression schema via an ARC connection on a 3" driver ...I'd love to hire you to come in and work on my staff as none of my 30 year acoustical engineers can do it, nor can an analyzer. When you learn how those extra bits are allocated, you'll probably feel sillier, but I'll just stop there.

So, you can convince yourself that you can hear 360Kbps of glorious audio bliss and massive improvement between DD and DD+ all you want, but the way the compression scheme works and bitstream is handled, it's pretty funny to see you try. But you do you boo. WIth 93% of the panels in the market not supporting DD+ via ARC and a fraction of AVR's out there doing it, you get 3 flavors chief...DD, DTS 5.1 and Stereo PCM ..and if you're foolish enough to think that DD+ is going to matter...well, can't help you chief. 😃

Care to provide since factual references to your claims? Where within the HDMI 1.4 specifications does it state ARC is capped at 1Mbps? I'm struggling to find the evidence for the physical limitation of the HDMI hardware that would prevent this or prove this.. It's troubling given reports by several people of their newer TVs handling some forms of DD+ over ARC which would imply that to some extent it is possible.

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