5.1 AAC problem on Plex

General Discussions
1

Hi guys… I’m using NVIDIA shield pro as Plex client. My Plex server is running from my Freenas server.

I don’t have any issues with audio format when I play movies using Kodi app… All the audio format are detected perfectly.

This is not the case in Plex. All audio formats are detected except 5.1 AAC… My Yamaha avr shows PCM instead of 5.1 Dolby. The same movie is detected 5.1 Dolby when I play it via Kodi.

All other formats are working except 5.1 AAC. Funny I don’t have this problem @ Kodi.

Please Help me guys.

FreeNAS server
2019 Nvidia Shield Pro
YAMAHA RX - V581

2

AAC is not Dolby Digital. So it doesn’t make sense to show Dolby if the file doesn’t have Dolby audio.

Which PCM? 2.0 or 5.1?

3

When I play using Kodi, 5.1 AAC file formats are detected as Dolby Digital 5.1.

Same movies at Plex are detected as PCM. Just PCM, i guess its 2.0. Like stereo.

4

That probably means that Kodi is converting 5.1 AAC to Dolby Digital. Plex doesn’t do that.
Your AVR doesn’t understand 5.1 AAC, so it only gets the basic audio format from Plex, which is PCM stereo.

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5

Owh… Thanks for your answers. I wonder how do i get surround working with 5.1 AAC format @ Plex.

It blows my mind how Kodi does it easily. Never had any issues with it.

Appreciate your help bro. Thanks.

6

Is the Shield connected directly to the Yamaha receiver?

Your receiver should support multi-channel PCM over HDMI connections.

Verify if the Yamaha is receiving PCM 5.1 or 2.0.


I’ve a Denon receiver. The front panel display shows “Multi-Ch In” when I play AAC audio on the Shield, indicating it is receiving PCM.

I can also press the INFO button on the remote. It pulls up an on-screen overlay on the TV that shows the input channels (visual verification of 5.1 vs 2.0).

The Denon does not support receiving AAC over HDMI. Therefore, the Shield (not Plex) converts the audio to PCM.

Conversion to PCM is preferable to Dolby Digital. PCM is lossless, so there is no audio degradation during the conversion.

Dolby Digital is a lossy format. Were Plex to transcode AAC to DD, the audio quality would be reduced by the process. Granted, the loss would be slight and you may not hear it, but it would happen nonetheless.

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7

This is what happens with my Shield/Yamaha combo: AAC 5.1 is simply sent as PCM 5.1 to the receiver. On my Roku/Yamaha combo, the AAC 5.1 is of course transcoded to AC3 5.1 since Roku doesn’t support AAC with more than two channels.

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8

Thanks a lot, I’ve learned a lot today.

Yes. The PCM is multi channel. I confirmed it with the info button at my Yamaha AVR. It’s 3/2/0.1

I was thinking PCM is only 2.0 stereo… Cool that my AVR can detect it @ multi channels .

Nvidia Shield is the best… :relaxed: :+1: :+1: :+1:

Appreciate your wonderful explanation. Thanks

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9

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