How does Plex deal with alternate audio formats?

General Discussions
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Or maybe this is more about how the industry handles alternate audio formats.

I am new to Plex and ripping DVD and Bluray disks. I know that many of my concert disk ISO have an audio menu where I can select different audio outputs. I have a nice HT system and typically go for the highest quality available.

Now I am using MakeMKV to rip tracks. I just did that for a music Bluray disk. I only found 3 tracks that were over 5 minutes long. Only one track was the actual concert.

So how are multiple audio “tracks” typically handled? What do I need to do (if anything) to get the highest quality audio option on playback through a Plex player?

(I did search for “audio formats” but didn’t get any hits in this discussion group. Sorry if I missed other threads that cover this topic.)

Thanks

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Track Selection

Plex defaults to the first audio track that matches your language settings. If you select a different track, Plex remembers that selection the next time you play the same file.

You can re-order the tracks and set/change language flags using MKVToolNix or similar tools.


Supported Audio Formats

Support for audio formats varies by Plex client. Unfortunately, there is no master list/matrix of which clients support which formats.

If the client supports an audio format, Plex will try to direct play it (stream it unaltered).

If the client does not support an audio format, Plex will transcode it to a supported format.


Example 1: Plex Web using Chrome on Windows 10.

Chrome supports AAC 2.0 audio. If you play a media file with AAC 2.0 audio, Plex will generally direct play it.

Chrome does not support Dolby Digital (AC3). If you play a media file with AC3 audio, Plex will transcode the audio to a supported format.


Example 2: Nvidia Shield and movie with TrueHD audio.

The Nvidia Shield can passthrough (bitstream) lossless audio formats such as TrueHD and DTS-HD MA.

If the attached audio equipment (receiver/soundbar/etc) supports the format, the Shield will pass it unaltered.

If the attached audio equipment does not support the format, Plex Media Server will transcode it to a supported format.


Real World Example

The Nvidia Shield Pro is the only off the shelf device that supports Dolby Vision, HDR10, and passthrough for TrueHD + Atmos and DTS-HD MA/:X audio.

If your audio equipment supports those formats, the preferred setup is:

Shield ← HDMI → Audio Gear ← HDMI → TV/Projector/etc.

The Shield will direct play the media (stream unaltered). The audio gear will play the selected track and pass the video to the display.

Some TVs block passthrough of TrueHD and/or DTS audio formats, so attaching the Shield to an HDMI input of the TV may not work.

Other scenarios are possible. It depends on your equipment and which video/audio formats you want to support.

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You need to differentiate between “titles” and “streams”. Each title on a disc can have several audio streams in it. Neither of which has necessarily to do with music “tracks”/“songs” like on an audio CD.
Sometimes after ripping, you will even end up with several titles which have the same video, but different audio in it.

In order to identify these things, you should get some free apps into your toolbox:

  • MediaInfo to see how many streams are in there and what format they have

  • MKVToolNix Downloads – Matroska tools for Linux/Unix and Windows to remove, reorder, or re-combine streams into complete files. Also handy to give those chapter markers meaningful names, so you can more conveniently jump to a certain song of a concert video in Plex.

  • a desktop video player. Most commonly used is VLC. For Windows though I rather recommend MPC-HC, since it has an open source software stack which is very similar to Plex’s.

Plex can handle several audio streams within a file. Each client will let you select the stream to play. Though it depends on the particular Plex client which of these streams can be played directly and in full quality, and which need to be converted by the server in order to use them.

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Thanks for the information. Clearly, I need to study this a bit more and try the tools mentioned.

My Preprocessor can handle pretty much whatever I select on the Bluray. I think the question will be what can the Fire TV HD 4K Plex player send through to the HDMI output. So I need to research that as well.

Remember the days of using RCA cables to connect the turntable to the preamp to the power amp and turning it on? Now you need an EE degree to set up the HT system. (I have one of those, and this stuff is still a bit daunting… lol)

Happy 4th.

5

If you have a capable audio decoder and you want the maximum possible quality, there is no way around the Shield Pro, IMHO.
Even if it’s already a few years on the market. It still regularly beats the cheaper options – particularly those which have been optimized for one particular streaming service and were never designed to handle the higher bandwidths and high quality codecs of disc-originated media.

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@OttoKerner is spot on about the Shield.

Basically, it sends everything as PCM, AC3, or EAC3 depending on how it is configured.

The most common configuration is to set the FireStick audio output to Best Available and the Plex app to Passthrough = HDMI.

This is how it behaves with my Denon receiver:
TrueHD: Transcoded by Plex Media Server to EAC3. Any Atmos info is lost in the process.
DTS (all variants): It will direct play. However, the FireStick will transcode the audio to EAC3.
AC3 & EAC3: Will passthrough, including EAC3 + Atmos.
AAC & PCM: Sent as PCM.

The FireCube v3 (current model) will passthrough TrueHD audio. However, for DTS, it only passes the lossy core.

FireTV Device Specs: Fire TV Device Specifications: Overview | Amazon Fire TV

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So something like this for the HT system?

[NVIDIA SHIELD Android TV Streaming Media Player; 4K HDR, live sports, Dolby Vision-Atmos, AI-enhanced upscaling, GeForce NOW cloud gaming, Google Assistant Built-In, Works with Alexa](

And then I can use Fire TV 4K sticks for bedroom TVs…

And Plex takes care of getting the best AV stream to each device…

That sounds like a winner!

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Important: nVidia Shield Pro
NOT the “tube” model.

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I see the difference, especially being able to take the Shield an a USB drive on the road. Also using a BT wireless mouse and keyboard to steer the Plex app.

It appears the streaming formats are the same? I checked out some YouTube reviews and they seemed to verify that, but I do not know if the reviewers were high end audiophiles.

I am really loving Plex@

Thanks!
.

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The only Plex Player I am really going to care about Audio on is the NVDA Shield Pro.

If my Bluray rip has multiple audio formats, will Plex automatically select the highest quality with the NVDA Shield Pro? ((It sounds like I will need to select it manually…)

If I use the tools mentioned previously to remove all but the best audio stream, will Plex recode the audio stream when being consumed by a FIRE TV 4K or a Xfinity set top box?

Part of me thinks picking the audio stream once and never having to worry about it again is the better approach for me…

Thanks again.

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See Track Selection in my reply to your first post.

See Supported Audio Formats in my reply to your first post.

The Xfinity set top box cannot access your Plex server. It can only access the free online media. This is a Comcast restriction. See Plex for X1 Overview.

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