Hey guys, I am sorry to start another audio question thread but I couldn’t find the answer to my specific question. Let me list some specs below and ill ask my question.
Server Version#: 1.20.4.3517
Plex host: Linux server VM
Plex Client: Apple TV 4K
Apple TV Settings: Video 4KHDR / Match Source Range and Frame Rate
Receiver: Denon AVR X1600H
Connection: Wired and on same network
Audio: 3.1 speaker system (connected to AVR; no Atmos speakers)
TV: LC 65" C8
My Apple TV works very well as my Plex client. I routinely stream 4k rips to it and it plays fine at 120Mbps+. I am not having any issues at all with video or audio.
I have done some reading about audio codecs and want to know if i am getting the full uncompressed audio out of Plex on my Apple TV or whether im leaving quality on the table. From the reading I have done, it seems that the Plex app for AppleTV doesnt support the Atmos channel, which is fine in my case cause i dont have an atmos speaker.
As an example, i have 1917 and when I play it, the plex player specs show “Transcode” but i know its just transcoding audio because the CPU hovers at <2% while its streaming. My receiver shows “Multi-Ch In” while playing this movie. This movie was shot in Dolby TrueHD 7.1 (48Hz. 24-bit) and the source file is a direct 4k rip as i own the physical disk.
Based on the above, i know the audio is being converted but not sure if it has an effect on quality. Can someone walk me through what steps/conversions the audio goes through from the source file to when it comes out my speakers? I know the audio has to be adjusted to account for my 3.1 setup not the original 7.1 it was shot in but my main concern is whether the audio is being converted losslessly or whether i am losing quality along the way.
Not trying to be facetious or mean, but really, I don’t see any way that you would be able to tell much of a difference with a non-atmos 3.1 whether the audio was converted lossy or not.
But to answer your question, you should be able to look at your plex server dashboard > Plex Web > settings > dashboard
and look at the audio transcode, it should say either truehd > flac/pcm (lossless), or to eac3/aac (lossy).
Hey thanks for the quick response! No offence taken.
I am relatively new to the home theater scene and am just getting started with my first setup. I will probably upgrade it over time starting with adding 2 more speakers for the rear to finish out the 5.1 setup.
My Plex web dashboard didnt show any player details under “status > Dashboard” but I checked the technical details dropdown menu on the client player and it says FLAC so i guess that means lossless audio.
The AppleTV will pass “Streaming Atmos,” which is Dolby Digital Plus + Atmos (used by Apple, Netflix, etc streaming services).
The AppleTV will not pass TrueHD audio, including “Blu-ray Atmos,” which is TrueHD + Atmos.
Check the settings on both the AppleTV and in the Plex app. From reading posts by others (I don’t have an ATV4K), the AppleTV should convert TrueHD 7.1 to PCM 7.1 then pass it to the Denon. Atmos information is lost, but the conversion from TrueHD to PCM is lossless. The conversion happens on the AppleTV, not the Plex Server, so the dashboard shows the audio is Direct Playing.
The Denon displays Multi-Channel In when it receives PCM audio. Press the INFO button on the remote and you should see an on-screen overlay on your TV showing input signal and channel mapping.
The Denon should map the incoming audio to available speakers. Choose the Auto sound mode, not Direct/Pure Direct. Use the Sound Mode buttons on the remote to cycle through the options.
I’ve a Denon 4300H and a 5.1.2 speaker setup. Here’s a pic of the on-screen display. This is playing dts-HD MA 7.1 from my Shield. For PCM, it would show Signal = MULTI-CHANNEL IN. You can also see the input signal layout and what speakers the receiver is driving.
What is the difference between Dolby Digital Plus and Dolby True HD?
So I am still seeing the technical specs on the Plex player say ‘transcode’ for the audio but I think thats because Plex is converting it to FLAC. Also don’t know why it says that under the Transcode Reason. Its clearly direct playing the video.
Dolby Digital (AC-3) and Dolby Digital Plus (EAC-3) are lossy audio formats, as is dts. TrueHD is a lossless audio format, as is dts-HD MA.
You’ll see Dolby Digital and dts on DVD discs. Blu-rays typically have TrueHD or dts-HD MA soundtracks. If a disc has a TrueHD audio track it must also have a Dolby Digital version. If a disc has a dts-HD MA audio track it must also have a dts version.
Dolby Digital Plus is typically used by the streaming services. I haven’t seen any movie discs with DDP audio tracks (not that the don’t exist, I just haven’t seen any).
See the Dolby Digital page on Wikipedia for additional details.
Based on the screenshots, it looks like you’re getting 7.1 lossless audio, so that’s a good thing. You could look at the Plex Dashboard as well, to see what it shows. It should show the same thing.
It is a little cryptic, but in Plex terms, it is direct streaming, not direct playing.
The audio is transcoding. To do this, Plex has to separate the audio and video, transcode the audio, then put them back together (remuxing).
Plex calls that Direct Streaming. Direct Playing happens when the server can stream the media unaltered.
Direct Streaming also happens when Plex needs to re-package the media. For example, if Plex needed to change the stream from a MKV to a MP4 container.
I meant to post a picture of my Plex dashboard. This is what its showing and when I click on the movie, it brings me to the movie page showing all the movie details. Not sure how to see the transcoding info. Maybe Im in the wrong place?
So to sum up what I have learned. If a movie is TRUEHD, Plex will losslessly convert the audio that to FLAC and then the Apple TV will losslessly convert it to PCM which the receiver sees.
If the movie is DTS-HD MA then Plex will direct play it to the Apple TV which will losslessly convert it to PCM for the receiver to see.
Hey I have one more question. I was looking at the screenshots from when I was playing The Bourne Legacy and noticed that:
The Plex server said direct play
The client said direct play
I didnt post a screenshot of it but on the Plex Client, if you go to the Playback Settings page DTS-MA HD 7.1 is selected as the audio format.
My question is that when I took another look at the screenshot of the Plex Client, it says ‘DCA’ under audio. What does that mean? You can see what im talking about below.
