[EAC3 Transcoding] Audio stutters on all Clients that do not support native playback

Plex Media Server Desktops & Laptops
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Server Version#: 1.30.1.6497 TrueNAS Scale 22.12 Official App & 1.30.0.6486 Synology DSM 7
Player Version#: Web 4.97.3, Android: 9.13.1.37459

I have severe audio stuttering issues on my movies that use EAC3 codec (sadly thats about 30% of my library). The video plays absoluteley fine but every client that does not natively support EAC3 has stuttering issues from the transcode. The issues manifest in audio cutouts every 0.5 seconds which makes any movie unwatchable.

Also while transcoding i can see that cpu usage remains at about idle lvl(4% per thread), whereas transcoding TrueHD Audio uses all 4 cores of my i5 3570k to about 55%. The files were transcoded with Handbrake to have a EAC3 bitrate of 1536 and are multichanel 5.1 or 7.1.

I googled around for a bit and found this, but my issue seems not to be related. As this issue also persists on my second plex server running on a synology DS218+.

Any help would be appreciated.

I have attached logs from my TrueNas Sever.
Plex Media Server Logs_2022-12-29_15-34-55.zip (324.4 KB)

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There is a known issue with the EAE / TrueHD.

We are currently testing the fix.

If you need things working now, you can use 1.29.2

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Thanks for the fast response!

I’ll try that on one machine for now then. Is there by any chance a known issues list?

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There is nothing publicly published because many of the “issues” we have open also include development activities.

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Makes sense. I’ll be keeping an eye on the release anouncements then to see if my issue is fixed.

Have a nice day!

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I can offer you a copy of the experimental version of PMS 1.30.3 to confirm everything works for you too ( TrueHD & other Dolby Codecs ) for Synology DSM 7 x86_64.

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I did a quick rollback on my TrueNas machine to 1.29.2 and it didn’t fix my playback issues. Also I have no playback issues with TrueHD Transcoding Audio.
I will try the experimental pms version on synology, but the machine is not on my home network, which makes accessing it a bit of a nuance…

UPDATE: Tried the experimental build on the synology as well and also had stuttering issues.

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I could replicate my transcoding problems with the following handbrake profile
eac3.zip (1.2 KB). I used the free to use Bick Buck Bunny video for testing. Which i got from here. Then i simply put it in my library and testet it with the web player (transcoding eac3 to aac) and my tv which can handle eac3 via passthrough. As before i have stuttering issues with the transcode, while the tv or direct play of the file on my pc (via VLC) is fine.
If needed I can provide the finished BBB file to you.

Hopefully we can resolve this together.

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@ChuckPa anything new? Should i encode a 100-200mb sample of the file for debugging?

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The fix is complete and will be included in the next update (AFAICT)

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That sounds awesome! Thank you for the info. Have a great 2023 :slight_smile:

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@ChuckPa The changelog for Version 1.30.1.6550 does not state E-AC3 audio transcoding fixes. And sadly my issue still persists with the new version. I now also tried this on my new server with an AMD Ryzen 5700X. So it really can’t be a hardware limitation problem.

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I was in the Engineering meeting today about this.

I have asked the server team. There should be an answer by the time I get up in the morning.

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Hey if you were hinting at Version 1.30.2.6563, I sadly have to tell you, that my issue still persists there as well.

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@ChuckPa Anything new on the issue?

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@ChuckPa Any chance this will get updated by plex or is this a problem with a used dependency?

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I’m retesting now with 1.31.1.6733

A lot got fixed in 1.31.1 builds.

I’m playing

  1. Truehd 7.1 movie snippet (which used to stutter)
  1. Dolby-official EAC3 demo.

Testing on Plex/web, Amazon FireTV 4K Max (9.16.1 release)
Forcing transcode to 320p resolution

I no longer have any stuttering

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I’m running 1.31.1.6733 as well but I am still having issues with my movies containing eac-3.

The two snippets you provided work fine for me. As a reminder i never had any problems with true-hd in the first place. Whats wierd is that the audio in the eac3 demo is not transcoding to aac if i play it with PlexWeb, which is happening on my movies that contain eac3.

Would it be of any help if i send you a snippet for my problem?
I can replicate the problem with the files provided in [EAC3 Transcoding] Audio stutters on all Clients that do not support native playback - #8 by b0urb0n_kid

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My file, which was labeled 7.1 — wasn’t. I apologize.

I grabbed proper Dolby 7.1 (from Dolby). I reproduce the failures. I’ve also reproduced other issues I wasn’t planning on plus some new ones.

I will work on this over the weekend if I have time. I have a lot of writing to do

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@ChuckPa Any updates on this? It makes Plex borderline unusable on Xbox if your audio device doesn’t support it and needs to transcode.