Rear and side surround Chanels swapped in advanced player

Plex Players Streaming Devices
1

Server Version#: 1.19.2.2711
Player Version#: 2.18 (15310)

Pretty much what the subject says. In a 7.1 setup, when playing a Dolby speaker detection file, the right rear channel is playing on the right surround speaker, and the right surround channel plays on the right rear. Same thing for the left channels.

If I use the old player, it outputs correctly. Testing outside of plex confirms my speakers are wired correctly. Test tones form receiver are correct, playing the file form Infuse is correct.

2

Sorry I did not add my server and player version before. I have updated the first post to include that info. I can also PM support logs, if requested. I turned on logging and then played the file twice, once in the old player, then once in the new player.

Hoping someone in support is seeing this, as decoding surround sound channels incorrectly, is kind of a big deal.

3

Anyone from Plex out there? Super frustrating when an clear issue is presented, and there is zero acknowledgement.

4

Thanks for your report! I took a look at your logs and nothing looked obviously wrong. Could you try setting a lower video quality in Settings -> Quality and see if it works right with the Enhanced Video Player?

5

Just got off work and was able to test. Thanks for helping address this issue.

If I set the Quality to Auto Adjust, it tuns OFF the enhanced player, and sound outputs correctly.

If I set Video Quality, Home Media Streaming to anything at a 1080p level, it outputs 7.1 audio, but still reverses the Rear and Side channel audio.

If I set Video Quality, Home Media Streaming to 720p, it outputs 5.1 audio (as confirmed by the enhanced video player debuging onscreen overlay.)

6

Hello, is there anything else I can provide or test? I provided a download to the file I am playing. Were you able to reproduce the issue?

Thanks,

7

I just tested it and seems to work fine here with the file you shared, but I’ll send you a DM with some stuff you could try if you have time :sweat_smile:

8

I though I’d made this part of our conversation public, since it might be interesting to other people:

I think I found the problem, and it’s in the Enhanced Video Player (called mpv). Not sure if you know about coding or if you’re interested, but seems like the first time mpv added support for multichannel audio for Apple platforms (macOS and iOS back then) got it wrong, and we’re talking about 2013: ao_coreaudio: simplify ch label to speaker id conversion · mpv-player/mpv@f10cca0 · GitHub

What you see there is how mpv maps channels from your video with channels to your sound equipment. I can’t blame them, because Apple documentation about audio channels is a bit confusing :joy:

We still need to do some testing on our side to make sure that’s the reason why this happen, but everything points in that direction!!

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9

Just received the beta 7.3 (16118) and the release notes indicated the fix for 7.1 audio was implemented. Eagerly downloaded it, tested and the audio is correct!

Thanks again for your help in resolving this issue!

1 Like
10

Thank you for your help testing the things I needed, it was invaluable to get this resolved! :smile:

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