I have hooked up my Roku Streaming Stick+ to a new Vizio SB36512-F6 soundbar and was hoping to experience Atmos (5.1.2). Unfortunately I’m only getting Dolby Digital. (The soundbar announces the identified signal.)
I have Roku system audio set to auto (DTHD, DD+, DTS). Roku is connected to the soundbar input (not ARC) and apparently it is correctly detecting that the soundbar supports TrueHD.
My source file is TrueHD 7.1 with Atmos and I set Direct Play = Force.
In this thread, someone says they are able to play 7.1 TrueHD with Plex running on a Shield.
Server Version#: 1.20.3.3483
Player Version#: 6.6.12.6662
The strange thing is, when I put my ear next the soundbar there is sound coming out of the height speakers when I height turned ON in the Vizio settings. If I change height to VRT then the height speakers are silent. I think VRT is supposed to upmix regular audio to “virtual Atmos”. When I play DD+ with Atmos from my smart TV, the soundbar identifies it as such, but with Plex it only says Dolby Digital. So I’m not sure what’s happening here.
Bad news: Roku’s don’t support Dolby Atmos or DTS-HD audio natively, sorry. They only support a modified version of Atmos used by streaming services like Netflix and Disney+, but that’s not what’s used in Blu-Rays (and as far as I know, there’s no way to encode the audio to support it).
Plex always needs to transcode audio when playing Atmos and DTS-HD on a Roku.
I think you’re right about Atmos, this is only supported on Roku Ultra, so I guess the object metadata would be ignored. But what about TrueHD? Here is a photo of the menu showing TrueHD.
So if the server is not transcoding, is the player transcoding TrueHD to Dolby Digital? Or is it actually playing TrueHD and my soundbar is mis-identifying the signal?
P.S. is there some reference to look up what audio id 188 means? I’m not familiar with that notation and it seems to not match anything in MediaInfo.
At first I believed it was playing TrueHD because the player and the log file said so. But now I have figured out this is probably a bug. I made a test file with TrueHD on track #1 and AC3 on track #2, using two different languages so it’s obvious which one is playing. Plex falls back to playing track #2 with no indication that it’s doing so. The player says TrueHD and the log file says direct play:
Nov 03, 2020 22:29:18.826 [0x7f90a6ffd700] DEBUG - [Transcode] Streaming Resource: Reached Decision id=31 codes=(MDE=1000,Direct play OK.) media=(id=70 part=(id=70 decision=direct play protocol=hls streams=(Audio=(id=202 decision= channels=0 rate=0))))
On the other hand, when I play a file with only 1 track of TrueHD, the player indicates transcoding and the log shows:
Nov 03, 2020 22:26:17.468 [0x7f90e27fc700] DEBUG - [Transcode] MDE: video has no video stream but does have an audio stream
Nov 03, 2020 22:26:17.468 [0x7f90e27fc700] DEBUG - [Transcode] MDE: Hans Truehd: Direct Play is disabled
Nov 03, 2020 22:26:17.468 [0x7f90e27fc700] DEBUG - [Transcode] MDE: Hans Truehd: media must be transcoded in order to use the hls protocol
Nov 03, 2020 22:26:17.472 [0x7f90e27fc700] DEBUG - [Transcode] MDE: Cannot direct stream audio stream due to codec truehd when profile only allows eac3
Nov 03, 2020 22:26:17.472 [0x7f90e27fc700] DEBUG - [Transcode] MDE: Hans Truehd: selected media 0 / 69
Nov 03, 2020 22:26:17.473 [0x7f90e27fc700] DEBUG - [Transcode] Streaming Resource: Added session 0x7f9104081fa0:ea4879ae808370654992fc15315a5651
Nov 03, 2020 22:26:17.473 [0x7f90e27fc700] DEBUG - [Transcode] Streaming Resource: Reached Decision id=30 codes=(General=1001,Direct play not available; Conversion OK. Direct Play=3000,App cannot direct play this item. Direct play is disabled. Transcode=1001,Direct play not available; Conversion OK.) media=(id=69 part=(id=69 decision=transcode protocol=hls streams=(Audio=(id=201 decision=transcode bitrate=1032 encoder=eac3_eae channels=8 rate=48000))))
I have just updated the Roku from 9.3 to 9.4 and now the system audio screen shows support for DTS-HD, where before it only showed DTS. Interesting. I was already able to play DTS-HD-MA without transcoding before the update and the soundbar identifies it as simply DTS. One of the devices must be discarding the lossless MA layer so it just plays DTS core.
Nov 03, 2020 23:04:07.999 [0x7f9102ffd700] DEBUG - [Transcode] Streaming Resource: Reached Decision id=27 codes=(MDE=1000,Direct play OK.) media=(id=66 part=(id=66 decision=direct play protocol=hls streams=(Video=(id=196 decision= width=1920 height=1080) Audio=(id=197 decision= channels=0 rate=0))))
I no longer trust the log file to say whether it’s transcoding or not, but I think a definitive proof is looking for Plex Transcoder process running in ps.
