AC3 Passthrough audio skips

[bakerms]

A complete description of this problem, with multiple logs and screen-shots can be found in the forums here:

https://forums.plex.tv/t/ac3-passthrough-audio-skips/375632

Logs also attached along with screen shot of playback info. logs.zip

Problem is that when using AC3 passthrough the audio will occasionally drop for a fraction of a second, causing the audio receiver to drop to 2 channel stereo for a fraction of a second. End result is that the audio skips. This happens randomly, it is not specific to a location in any particular video file, but happens on all video files.

Note that this occurs only when playing through Plex. Playing back the same video files through VLC results in no skips or issues. This happens on video files recorded by Plex DVR, as well as Handbrake encoded movie files.

Test environment

PMS Version: 1.15.6.1079 (latest version as of 5/27/2019) PMP Version: 2.34.0.983 (latest version as of 5/27/2019) Platform (Windows/macOS/Embedded RPi/Embedded Intel): Windows 10 64-bit

I have verified that my audio and video drivers are current, as are PMS and PMP. All other windows updates have also been applied.

Computer is running Windows 10 64-bit, connected directly to the TV by HDMI, connected directly to the audio receiver by optical S/PDIF. Problem also occurs when connected by digital coax, or by HDMI (as reported in the forum thread). Computer is new, i5-8400, 32 GB ram, SSD boot disk and WD Red 4 TB disk storing my media.

In my configuration, the Plex Media Server and Plex Media Player are both running on the same computer, directly connected to my TV and audio receiver.

Steps to reproduce

1. Problem is reproduced on my system when audio passthrough is enabled. It occurs randomly. Sometimes 30 minutes can pass with no skips and then audio will drop out multiple times in a few minutes. Rewinding video file to the same spot does not cause drop out to repeat, it is random in the file. I have changed every setting I can think of that might affect this with nothing eliminating the problem (other than disabling passthrough).

Current behavior

1. Audio randomly drops out for a fraction of a second during playback of video files with AC3 passthrough enabled.

Expected behavior

1. Expect Dolby Digital 5.1 audio to play back smoothly without dropping or skipping when audio passthrough is enabled.

[dan-the-man-nz]

this is something i experience as well, in the end i gave up and switched off passthrough which resolved the issue

Was also running PMP on Windows (same machine as Plex Server)

can also confirm: audio does not drop out in same spot

like you i tried many things to fix, different drivers, settings on receiver, no luck

other media players didnt have the same issue with passthrough (kodi, mediaportal, latest mpv video player) back when i was trying to fix this. However noone else seemed to be complaining so i just put it down to my system at the time.

[mseeley]

Thanks for filing this @bakerms. I've labeled this for pickup along with other AV integration issues.