Server Version#: 1.19.1.2645 (QNAP)
Player Version#: 4.29.3 (WebOS 5.0.0)
This is a new one for me. I have a content that’s encoded as 4K (HEVC Main 10 HDR). The associated audio track is DTS-HD MA 7.1. I’m using the built-in speakers on the TV for the purposes of simplicity in troubleshooting. When I pay the content, the video is fine (and displayed as HDR). There is, however, no audio.
When I look at the debug data on the TV, the field ‘Can Direct Stream Audio’ is set to false.
‘Is Direct Play’ is set to true, and ‘Can Direct Play Video’ is also set to true. Protocol is set to ‘http.’
Setting - Dolby Digital (AC3): true
Setting - Dolby Digital Plus (EAC3): true
Setting - DTS (DCA): true
The relevant audio data:
Audio Channels: 8
Audio Codec: dca-ma
Audio Profile: ma
Bitrate: 21164
Container: mkv
Video codec: hevc
Video framerate: 24p
Video Profile: main 10
Dimensions: 3840x1600
Here’s where it gets weird. If I transcode the video/audio down to non-HDR 1080p, the audio works. In that config, the changed settings are:
Is Direct Play: false
Can Direct Stream Audio: false
Can Direct Stream Video: false
Protocol: hls
I haven’t researched it a lot but it probably has to do with the amount of data requires for DTS-HD MA 7.1. and or how it’s linked to the video file. Something else I’ve seen is that if you tried to play that video on another TV, it wouldn’t even attempt to play it because the TV’s aren’t supposed to be able to pass the DTS-HD MA 7.1. signal to the receiver or even decode it for that matter, the server typically sees and knows this and will automatically transcode the audio. This does not happen with LG’s and I know this because I’ve had 2 LG’s that will pass HD audio via ARC. Because of this, there seems to be some conversion in the Plex realm that isn’t working properly because the TV isn’t supposed to be able to see and understand that File format.
This is all just my take on the issue and I would love if someone else could say yes or no to my conjecture…
The 2020 Series of OLEDs from LG (CX, GX, etc) do not support DTS. It has been removed from being a supported audio codec. You must either pass the DTS to an AVR, or transcode it to another audio codec.
You also cannot pass DTS over ARC / eARC, as passthrough on the TVs has been disabled for DTS as well.
I had to reinstall plex because on my Synology DS218+ Nas hardware acceleration wasn’t working what appeared to be a common problem after a DSM update.
Only thing is that it is transcoding not only DTS but also Atmos en other HD autio formats. Dolby Digital AC3 does directplay.
For some dumb reason LG have stopped support for DTS with 2020 models. I believe if you use a Nvidia Shield Pro and in a limited way ATV and or with Infuse.
No need for a shield (i have one but don’t need it) because Plex can transcode it to lossless multichannel PCM that the LG CX understands. That goes flawless to my receiver using eArc!
Only thing I still want a solution for is Dolby Atmos because Plex somehow transcodes this to Multichannel PCM.
Maybe the new Firmware update will fix this issue.
I’ll be using a Sony STR-DN1060 which supports ARC/optical. As I understand it ARC only supports PCM2.0/DTS/AC3.
If I bought the C9 this wouldn’t be such an issue because most of my content has DTS audio tracks.
If I bought the CX, I imagine the only 5.1 format I’d be able to use would be AC3 via ARC. Will plex be able to convert DTS-HD/TrueHD/DTS etc to AC3 or will I be without 5.1 audio?
With ARC you’ll get dts/ac3/eac3 up to 5.1 channels. EAC3+Atmos is also supported. PCM is 2.0.
I’ve an LG B7 OLED connected to a Denon 4300. Using the Plex app on the LG:
TrueHD transcodes, as it is not supported by ARC.
dts-HD MA up to 7.1 channels direct plays, but only the 5.1 core is passed over ARC. The “-HD MA” part is discarded. Note that the B7 supports dts audio, so not sure what will happen with models lacking dts support.
AC3/EAC3/EAC3+Atmos/dts up to 5.1 all direct play / passthrough to the Denon w/o issue.
