[spinmaster]

Hi,

before I try my luck on Sonos forums, I wanted to give the Kodi forum a try. I am running Kodi 19.3 (LibreELEC 10.0.1) with the Sonos Beam Generation 2 Soundbar for a while. The Sonos Beam 2 is already capable with Dolby Atmos 5.1 Surround Sound (which works perfectly on my Kodi Setup). End of 2021, DTS surround sound support was delivered by Sonos with an update - but I cannot get DTS to work on Kodi.

Any Sonos Beam 2 users here who got DTS to work on Kodi?

My setup works flawlessly for Dolby Atmos with the Beam:
 

• eARC Port on my LG TV is used
  
• High Quality HDMI 2.1 cable is in place
  
• Passthrough in Kodi is activated
  
• Dolby relevant codecs have been enabled in Audio Settings in Kodi
  

However, when I enable "DTS" in Kodi Audio settings and use a DTS movie source from my Library, I do not get any sound at all and an error "Audio is not supported". Tried multiple movie sources with DTS audio codec - same result.

Am I missing something? I have tried and enabled all DTS codecs in the Kodi audio settings with no luck. See screenshots for my settings with the Beam 2 and the error in Kodi when a DTS sound source is played.

Any help would be appreciated!

[fritsch]

Can you rule out the TV by directly attaching the cable into the Sonos somehow?

[jjd-uk]

What LG TV as LG stopped supporting DTS passthrough for the last few generations of their TV's. I think the 2019 9 Series TV's were the last one's to do DTS.

[spinmaster]

Thanks both. I would rule out the general passthrough setup, as it works perfectly with Dolby Atmos surround sound with both Sonos Beam 2 and Kodi. After Sonos released the DTS update last November, I would have assumed that it's just a matter of enabling DTS codec in Kodi audi settings and that's it.

However, what @jjd-uk wrote makes me worried and that would be a bummer...   I have a LG OLED55BX9LB 4K TV which I bought in February 2021 (model year according to specs is 2020). Do you have source for your assumption? Would this basically mean that there is no way to pass through the DTS signal from my movie source played in Kodi via HDMI/eARC to the Sonos Beam 2, even though the Beam 2 supports DTS audio?

[jjd-uk]

No DTS passthrough on that TV see https://youtu.be/mrSU3tiNLSM

Just about everyone except Sony has removed the ability to passthrough DTS from their TV's in the last few years.

[spinmaster]

Thanks for confirming ... very disappointing though. I was aware that there are general licensing issues between DTS and certain TV brands (LG, Samsung, etc.) - however, I always assumed that these licensing issues are affecting only DTS playback on the TV itself (hence, why these brand did not support DTS natively - or at least not any longer).

I never thought that these issues would also affect simple passthrough of the (DTS-) signal to the end device such as an external soundbar. Why would the TV brand not "allow" this? Understand that it does not support the DTS playback directly on the TV, but why does the DTS licensing also affect the passthrough?

Anyway, I will stay away from any sources with DTS from now on and prefer Dolby. Not really a big difference audio wise for my ears between the two anyway. It's just that I still have 150 or so movies with DTS audio in my library which are now forced to be played in Stereo.

Thanks for the heads up!

[jjd-uk]

It can be solved but would involve the expense of getting something like https://hdfury.com/product/4k-arcana-18gbps/ which is not cheap, however there maybe similar devices that are cheaper. So it depends on how important DTS is to you whether you can be bothered.

[black_eagle]

Just to say, it's never a good idea to go Kodi->tv->avr/soundbar.  Much better to go kodi->avr/soundbar->tv wherever possible if you want high end audio.  TV passthrough capabilities are usually meh.

[fritsch]

Thanks for confirming ... very disappointing though. I was aware that there are general licensing issues between DTS and certain TV brands (LG, Samsung, etc.) - however, I always assumed that these licensing issues are affecting only DTS playback on the TV itself (hence, why these brand did not support DTS natively - or at least not any longer).

I never thought that these issues would also affect simple passthrough of the (DTS-) signal to the end device such as an external soundbar. Why would the TV brand not "allow" this? Understand that it does not support the DTS playback directly on the TV, but why does the DTS licensing also affect the passthrough?

Anyway, I will stay away from any sources with DTS from now on and prefer Dolby. Not really a big difference audio wise for my ears between the two anyway. It's just that I still have 150 or so movies with DTS audio in my library which are now forced to be played in Stereo.

Thanks for the heads up!

They aren't. In kodi, select Speakers 2.0, enable Dolby Transcoding, enable AC3. From that on all multichannel files will be transcoded to AC3 and output as 5.1 properly.

[spinmaster]

Thanks all for your input @jjd-uk , @black_eagle , @fritsch ! Really helpful. I did some more research and some testing last night ... if you search further for this topic, it looks I am not alone (see e.g. here: https://forums.whirlpool.net.au/archive/3m011w66).
 

They aren't. In kodi, select Speakers 2.0, enable Dolby Transcoding, enable AC3. From that on all multichannel files will be transcoded to AC3 and output as 5.1 properly.

This is interesting and I wasn't aware of this at all. I can confirm that this works as you described, based on my Sonos app (which shows the outputted audio stream from the Sonos Beam 2 Soundbar).

When I play a DTS source file in Kodi, have DTS disabled in audio settings and Dolby Transcoding disabled, the Sonos app shows the audio as "Stereo PCM 2.0".
When I play the same DTS file, have Dolby Transcoding enabled in Kodi settings, the Sonos app shows the audio output as "Dolby Multichannel PCM 5.1". Cool!



Sooo... what does this mean for my initial "problem"? Is this the "fix" or workaround what users generally should do if they have a 5.1 surround capable audio system (like my Sonos Beam 2 soundbar) - but cannot receive a "licensing protected" audio codec like DTS because e.g. their TV is blocking the same - like LG in my case? Was this the intended usecase when this feature was introduced in Kodi?

What happens in the background? You are taking a DTS compressed audio stream and transcoding it into Dolby AC3 since it's an open multichannel format?

Lastly: how would the AC3 transcoded output match up with a "native" DTS output on a Soundbar (e.g. on another setup with a 2019 LG model, where the DTS signal would be passed through)? Do you think you would hear a difference? Is one "better" audiowise than the other?

Sorry for the additional questions - but I would really like to understand it. Also I am sure other users mights be interested too, as a newer LG TV and Sonos is a setup which other Kodi users likely use as well.

Appreciate your help and sharing your knowledge!

[jjd-uk]

The DTS stream gets decoded to LPCM and then that LPCM stream gets encoded to AC3. This could result in a theoretical drop in quality if it's 768/1512khz DTS stream since the AC3 is fixed at 448khz I think. It also means you can't get Multichannel PCM out from say a AAC 5.1 stream, as that would also be encoded to AC3.

[jjd-uk]

I was perhaps a bit fixated on keeping the DTS as DTS before, as the other possible solution is leaving Number of Channels at 5.1, then disabling the DTS options. So Kodi still decodes to LPCM, but doesn't do an unnecessary encode step, as long as the HDMI path supports Multichannel PCM all the way through to the Sonos. I think that LG TV is capable of passing Multichannel LPCM, although the video I posted before shows 2 channel LPCM, I believe that it was fixed in an update, unless it's only the step up CX and higher models that do that. Although some models of LG having bugs/issues Multichannel PCM so it might worth sticking to transcoding to AC3, personally I prefer to keep any manipulations of audio to a minimum. As for the Sonos, I think that also does Multichannel PCM now via one of the early updates.

[jjd-uk]

Regarding Sonos I got myself confused with the Sonos Arc, as that launched without Multichannel PCM then had it added later. I've not really followed the launch of the Beam Gen 2, but from a quick look they changed to eARC HDMI for the Gen 2 so it should also be capable, however I don't know if Multichannel PCM is supported when it comes to the Beam Gen 2.

[edit] Seem's it does https://support.sonos.com/s/article/4945?language=en_US

[spinmaster]

Thanks for explaining and sharing these insights @jjd-uk ! I will continue using the AC3 Transcoding in Kodi for my DTS movie sources from now on. Glad you & @fritsch have pointed this out. I've marked this thread as solved.

[jjd-uk]

As a further bit of background.

In case you don't know, bandwidth for audio is commonly expressed as number of channels, where those channels are uncompressed PCM. So when you set Kodi to Number of Channels 2.0 you're telling Kodi the connection can only handle only 2 PCM channels and so it's not capable of Multichannel PCM (more than 2), this is necessry most commonly where the connection is either a SPDIF (optical or electrical) connection or a ARC HDMI connection, since that is all they can handle when it comes to umcompressed PCM. However it should also be noted that Number of Channels is not always the same as the Number of Speakers, since encoded formats like AC3 and DTS compress the audio so it's much smaller in size, hence why AC3 5.1 fits down a PCM 2.0 pipe so you still get 5.1 even when Number of Channels is set to 2.0.