Lossless audio formats

General Discussions
1

I’ve searched some topics and I found something answers where you could set the option for audio to lossless formats, although I’m still not sure if it’s supported.

I ripped my home collection to ISO files, muxed them and encodes them so they are a little smaller (CRF 17-19). I always let the lossless audio format in the mkv. But I want to know how to have my Plex play these lossless audio formats, like DTS-HD and TrueHD. How do I manage this? Or is adding them and using ‘‘Direct play’’ enough to enable the lossless audio format?

I hope someone can give me the answer:)

2

I would like to know if 24bit and 32bit audio files are being down sampled for playback from remote locations. And, are DSD, DST, DSF going to be supported in the near future? It would be nice also if ISO files could be read, and their contents added to the library.

3

@“Admin Deadpool” said:
I’ve searched some topics and I found something answers where you could set the option for audio to lossless formats, although I’m still not sure if it’s supported.

I ripped my home collection to ISO files, muxed them and encodes them so they are a little smaller (CRF 17-19). I always let the lossless audio format in the mkv. But I want to know how to have my Plex play these lossless audio formats, like DTS-HD and TrueHD. How do I manage this? Or is adding them and using ‘‘Direct play’’ enough to enable the lossless audio format?

I hope someone can give me the answer:)

It depends. :slight_smile:

It depends on your Plex client and your audio system. Your client and audio system must support the audio codec or Plex will transcode the audio into a compatible format. This is true for any audio format, not just lossless.

Here’s some scenarios:

Scenario 1a: Plex app on Smart TV. Connected to Receiver via HDMI/ARC or optical TOSLINK.

This plays lossy codecs - AC3 5.1, dts 5.1 - just fine. Also PCM up to 5.1 (Wikipedia Info). However, it does not have the bandwidth to carry lossless codecs such as TrueHD or dts-HD MA. So, Plex will transcode the lossless audio into a lossy format such as AC3 or AAC (varies by client).

Note: eARC (extended ARC) is slowly making its way to market. It will handle lossless audio formats.

Scenario 1b: Amazon/Roku/etc streaming box connected to TV via HDMI. Audio to receiver via HDMI/ARC or optical TOSLINK.

No different than Example 1a. HDMI/ARC or TOSLINK is the limiting factor.

Scenario 2: Amazon/Roku/Nvidia/etc box/stick connected to receiver via HDMI, receiver to TV via HDMI

Device <–HDMI–> Receiver <–HDMI–> TV

First, the receiver must support the desired audio codec. If it does not, Plex will transcode the audio.

Second, the streaming device must support the desired audio codec. If it does not, Plex will transcode the audio.

Example A: Device = Amazon Fire TV box/stick/pendant. Assume receiver supports all desired codecs.

Result A: Amazon devices do not support any dts audio stream, so such streams will be transcoded. Amazon support for Dolby audio formats varies by device (see tech specs).

Example B: Device = NVIDIA Shield TV. Assume receiver supports all desired codecs.

Result B: The NVIDIA Shield TV supports bitstreaming lossless audio codecs (Dolby TrueHD, Dolby Atmos, dts-HD MA, dts:X). So, it will pass the desired audio format to the receiver. PMS shows Direct Play or Direct Stream, depending on what is happening with the video content.

Other devices - Roku / AppleTV / other Android TV boxes / etc - have other capabilities. You’ll have to check their specifications to see how they will behave.

Summary: It Depends. :smiley:

You have to do some homework. Make sure everything in the audio path supports the desired audio format. If something does not, then the audio will transcode.

1 Like
4

@IsaiahSellassie said:
It would be nice also if ISO files could be read, and their contents added to the library.

https://support.plex.tv/articles/201426506-why-are-iso-video-ts-and-other-disk-image-formats-not-supported/

5

So, if I am running Plex on Apple TV 4 and streaming a 24bit FLAC music file over the home network, will it keep the full source resolution?

6

@FordGuy61 said:

-Sorry for the late answer at first -

As for the receiver, I have an Soundbar which supports TrueHD/DTS-HD. Should that mean that:

Nvidia Shield → Soundbar → TV. All with HDMI ofcourse. But to which do I apply the ARC? My TV and soundbar has this option. So I use this: (?) Nvidia Shield → HDMI towards ‘‘HDMI in’’ on Soundbar → HDMI ‘‘ARC’’ from the soundbar towards ‘‘ARC’’ from the TV.

Should that be the setup? Or will I need a whole different receiver to make it work?

7

Short Answer: You’ve got it right. ARC is between TV and soundbar, and is not needed between Shield and soundbar. Play one of your MKV files w/ TrueHD or dts-HD audio & see what happens.

ARC passes audio from the TV back to the soundbar. It is needed if you use the over the air tuner in your TV or YouTube etc app if you’ve a smart tv, etc. Before ARC people had to run a separate audio cable from the TV to their soundbar/receiver. With ARC you just need one cable instead of two.

Troubleshooting Tip: In Plex app on Shield, set Display Information = On. When playing video, pull up on screen controls (pause, etc). Look in upper left corner. It will tell you if media is direct play / direct stream / transcode and give a reason if direct stream or transcode. Think this is a feature for Android TV clients, as it works on Amazon Fire TV devices as well.

You can also check status with Status → Now Playing: https://app.plex.tv/desktop#!/status/playing. It will show Direct Play, Direct Stream, Transcode.

Long Answer:

First a caveat: I don’t have a soundbar. In theory, a soundbar acts like a receiver + speakers in one package (Scenario 2 in my original reply). In practice, there can be implementation issues specific to various makes & models (happens w/ receivers too).

With the Shield connected directly to the soundbar you do not need ARC for Plex, or any other Shield app, to work. The Shield sends audio + video to the soundbar. Soundbar decodes & plays audio and sends video on to the TV.

As long as the soundbar supports the audio stream, it will Direct Play. Otherwise, Plex will transcode the audio to a format supported by the soundbar. This is where “in practice” comes into play. There have been implementation issues w/ some soundbars resulting in transcoded audio when it should seemingly Direct Play. If you run into this, you can search the board for answers or open up a thread and include details such as soundbar make/model, PMS version, and Plex client version along with a good problem description. Chances are somebody has already run across the same problem and can help.

As long as the TV supports the video stream (H264, H265, etc), it will also Direct Play. Otherwise, Plex will transcode the video. Plex currently transcodes all video to H264 1080p or lower. 4K & 1080p transcode to 1080p. Lower resolutions match the source (i.e. DVDs transcode to 480p, not 1080p).

Regarding Audio Return Channel (ARC):

ARC is used to pass audio from the TV back to the soundbar (i.e. TV (A)udio (R)eturning along the HDMI cable to the soundbar).

As mentioned above, you do not need ARC for Plex app on the Shield when Shield is connected to the soundbar.

You do need ARC if you use the over the air tuner in your tv, any apps such as YouTube if you’ve a smart TV, or if you’ve a cable box, blu-ray player, or similar device attached to the TV. On the TV there will be a specific HDMI port that supports ARC. Connect that port to the soundbar port that supports ARC. Check the TV settings as well. ARC is not always enabled by default.

Hope this helps. Probably way too long and way TMI. :slight_smile:

Cheers.