Server Version#: 1.19.4.2902
Player Version#: 8.1.2.18135
Hi Guys,
I have just received the new Sonos Arc soundbar which supports all the Dolby Codecs (including TrueHD Atmos) however it doesn’t support DTS of any kind (thanks Sonos). I’m having problems maintaining the full array of Dolby codecs whilst avoiding DTS being output as 2.0.
Current config:
Plex Audio - HDMI Passthrough
nVidia Shield TV 2019 - Manually defined audio formats with everything selected excluding DTS
LG C9 - Set to Passthrough with eARC enabled.
With the above config everything Dolby works brilliantly including TrueHD Atmos however DTS/DTS HD MA output at PCM Stereo. I know Plex can transcode DTS to AC3 however clearly my array of configuration parameters prevents the transcoding from doing this.
There is much discussion on how to encourage DTS to AC3 transcoding with previous Sonos products (selecting Optical Passthrough and unchecking DTS as a codec) however all of these solutions become irrelevant with a product which supports True HD without supporting DTS.
Am I hitting a limitation within Plex here or do I have a bad configuration?
All the best,
George
P.S. I appreciate ‘Sonos should allow DTS’ themed replies but sadly they don’t and I think all the ingredients exist to work around this somehow.
I think Sonos have managed to make the only soundbar to support True HD and not DTS of any form.
I’m guessing this isn’t a combination of audio codes that is particularly common to Plex and thus there is no option to tell plex to “Allow True HD but transcode DTS”. Instead It appears the only option is to limit DTS on the shield itself which forces PCM 2.0 whenever DTS tracks are played.
All the documentation for Bitstreaming from the shield suggests that “Plex will detect supported audio codecs” but I’m not sure how well this works with eARC given then Plex connects to the TV, maybe the TV is advertising DTS but when DTS arrives at the Sonos Arc there is no sound.
In my head the only solution to this is some form of manual override to the bitstreamed audio codces within the plex app (a bit like PMP or PHT used to have) but I appriciate there is possibly a limited audience who would benifit from this.
I’ll continue to post any findings as I go. Perhaps some others might have some input as the Sonos Arc becomes more popular.
Same problem here, all things work, but DTS is not transcoded to AC3 DD5.1, only getting Stereo.
For now I have installed Kodi on my Shield Pro 2019 and with Kodi also all functions work (Atmos/UHD/Subs),but also all DTS is now trancoded to AC3 DD5.1.
So until there is a fix, I stick to Kodi.
I don’t have the same setup as you, instead I go through a receiver, then to TV.
But, when I disable DTS in manual format selection (shield OS) I get multichannel PCM for DTS tracks played back in Plex.
I’d imagine it’s doing the same for you. So if you’re getting only stereo to your sonos then that would imply the TV is not passing through PCM 5.1 even though eARC should support it.
Thanks for sharing all of your feedback everyone. We will be adding Multi-Channel LPCM support to Arc as part of a future software update. We don’t have exact timing to share at this point and will update this thread when we do.
So Plex could still output a DD5.1 stream if it wanted to but LPCM would be better so there’s no real problem for me to wait.
Just ordered an Arc after upgrading my Tv to the LG OLED 65 C9 and now I’ve started reading these reports on audio playback qwerks
I currently have the Sonos Playbar and that quite nicely downmixes DTS to AC3 5.1 Dolb Digital. Am I right in thinking any movie I have (not matter the resolution) if it has DTS I will only get stereo until Sonos apply a fix??
Correct. Assuming you’re using the native Plex app. Kodi (with Plex addon) works fine.
For completeness I feel Plex could offer more granularity around audio control to force transcoding in certain situations but I suspect the number of people who would benefit is relatively small.
Wait for Sonos update (for multichannel PCM) or use Kodi for now.
One last question George, if the PCM issue is on the Sonos side how does Kodi get around this in order to successfully downmix? (or have I missed something)
Because Kodi has the ability to selectively disable the codecs which the Arc can’t use. This then tells Plex to transcode. So DTS can then be transcoded to AC3.
The Plex app doesn’t have that level of granularity in its config.
Overall the Arc is a much better product than past Sonos soundbars. Much wider soundstage and much more stereo separation. The vertical element of Atmos I would describe as atmospheric rather than game changing. But I think that’s largely true of all upward facing speakers.
For me, Atmos has always brought noticeable improvements in all dimensions rather than just height and that’s true here.
I do have a “separates” setup in another room with Atmos support (no heights though) and the Arc has definitely closed the gap.
Plex needs to detect/be told that this sound bar can play TrueHD but not DTS. Presently it’s not doing that correctly. I suspect it’s effectively grouping Lossless codecs together in some way.
When Plex (incorrectly) sends DTS to the sound bar we get PCM. Emby is clearly doing a better job at detecting compatible audio codes in this situation.
It is a strange situation though. It’s not common for Dolby True HD to be supported with no DTS so I can understand why Plex hasn’t catered for this combination. For sure they could (like Emby & Kodi).
I’m just scratching my head on how Emby does what I would think Plex should be able to also, on top of that noticing that Plex has some trouble at EAC3 on high bitrate (1536kbps) and Emby doesn’t.
Interestingly today my Arc home theatre was complaining that it couldn’t connect to ‘the master’ (or something) so I had to power cycle the equipment.
Since then (or maybe before) I am not getting any dialogue from Plex with DTS. I’m only getting ambient sounds (basically i think I’m missing all the channels excluding the L+R).
Is anyone else getting this issue? Unfortunately i don’t know if there is some other update which has broken this or just my system being flakey.
LG c9 Firmware 04.80.03 has this in it’s release notes:
The device codec capability configuration (EDID) for the LPCM codec changed from 2 channels to 8 channels, so the 2019 models can Pass-Trough multi-channel PCM audio via eARC
I suspect that the C9 is advertising it’s ability to handle LPCM to the shield and now the shield is sending up to 8 channels whereas before the shield was probably sending only 2 channels.
The TV is then sending all 8 channels to the ARC of which the ARC is ignoring them excluding the 2 front channels.
