PLEX audio dropouts and sync issues with seamless branching on 4K TrueHD/Atmos movies

Plex Players Streaming Devices
1

Server Version#: 4.69.1
Player Version#:

Windows 10 based rack server → PLEX server → MakeMKV 4K HDR Dolby Atmos movie → Cat6 Ethernet → NVidia Shield 2017 → PLEX player

Sound drops and then goes out of sync when it comes back on EVERY seamless branch point in movie.

Happens on the EXTENDED CUT of movies which use seamless branching.

Examples of movies affected noticed by me and another MakeMKV user

Black Hawk Down 4K (One I noticed)

Halloween Kills 4K

Fast Furious 9 4K

The Martian 4K

Hellboy (2004) 4K

M3Gan Bluray (at least 10 occurrences in this movie)

Stripes 4K

Mentioned to you before on this thread: Audio Dropouts (TrueHD 7.1 Atmos) Plex on Shield Pro (2019)

More information on this post: The Natural/Black Hawk Down - www.makemkv.com

Also people found same issue on this Reddit post: Reddit - Dive into anything

Is PLEX aware of this serious problem? Anyone looking to fix it?

If you want to reproduce this issue please buy this Amazon disc: https://www.amazon.co.uk/gp/product/B07KLFM6L5/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Details of Black Hawk Down 4K file

> General
> Format                                   : Matroska
> Format version                           : Version 2
> File size                                : 59.8 GiB
> Duration                                 : 2 h 31 min
> Overall bit rate mode                    : Variable
> Overall bit rate                         : 56.4 Mb/s
> Movie name                               : Black Hawk Down
> Encoded date                             : UTC 2021-12-23 12:24:38
> Writing application                      : MakeMKV v1.16.5 win(x64-release)
> Writing library                          : libmakemkv v1.16.5 (1.3.10/1.5.2) win(x64-release)
> 
> Video
> ID                                       : 1
> ID in the original source medium         : 4113 (0x1011)
> Format                                   : HEVC
> Format/Info                              : High Efficiency Video Coding
> Format profile                           : Main 10@L5.1@High
> HDR format                               : SMPTE ST 2086, HDR10 compatible
> Codec ID                                 : V_MPEGH/ISO/HEVC
> Duration                                 : 2 h 31 min
> Bit rate                                 : 51.7 Mb/s
> Width                                    : 3 840 pixels
> Height                                   : 2 160 pixels
> Display aspect ratio                     : 16:9
> Frame rate mode                          : Constant
> Frame rate                               : 23.976 (24000/1001) FPS
> Color space                              : YUV
> Chroma subsampling                       : 4:2:0 (Type 2)
> Bit depth                                : 10 bits
> Bits/(Pixel*Frame)                       : 0.260
> Stream size                              : 54.8 GiB (92%)
> Language                                 : English
> Default                                  : No
> Forced                                   : No
> Color range                              : Limited
> Color primaries                          : BT.2020
> Transfer characteristics                 : PQ
> Matrix coefficients                      : BT.2020 non-constant
> Mastering display color primaries        : Display P3
> Mastering display luminance              : min: 0.0050 cd/m2, max: 4000 cd/m2
> Maximum Content Light Level              : 4000 cd/m2
> Maximum Frame-Average Light Level        : 1391 cd/m2
> Original source medium                   : Blu-ray
> 
> Audio #1
> ID                                       : 2
> ID in the original source medium         : 4352 (0x1100)
> Format                                   : MLP FBA 16-ch
> Format/Info                              : Meridian Lossless Packing FBA with 16-channel presentation
> Commercial name                          : Dolby TrueHD with Dolby Atmos
> Codec ID                                 : A_TRUEHD
> Duration                                 : 2 h 31 min
> Bit rate mode                            : Variable
> Bit rate                                 : 3 947 kb/s
> Maximum bit rate                         : 6 000 kb/s
> Channel(s)                               : 8 channels
> Channel layout                           : L R C LFE Ls Rs Lb Rb
> Sampling rate                            : 48.0 kHz
> Frame rate                               : 1 200.000 FPS (40 SPF)
> Bit depth                                : 24 bits
> Compression mode                         : Lossless
> Stream size                              : 4.19 GiB (7%)
> Title                                    : Surround 7.1
> Language                                 : English
> Default                                  : Yes
> Forced                                   : No
> Original source medium                   : Blu-ray
> Number of dynamic objects                : 11
> Bed channel count                        : 1 channel
> Bed channel configuration                : LFE
7 Likes
2

I’ve had this issue as well, but I’m not sure any streaming player can play these back without this problem. I’ve only had correct playback on Plex for Windows, which uses SW decoding and discards the Atmos.

I currently convert these to FLAC for proper playback (sans Atmos) on my Shield, but looking forward to this issue being figured out as well so I can add the Atmos tracks back in.

1 Like
3

I was able to reproduce this. Will discuss with @ChuckPa to further test and discuss with devs.

4 Likes
4

More good technical details here. I don’t think you should hold your breath for set-top players to both transparently correct the broken audio AND pass the audio through.

Is there any method for ripping & fixing these (offline) that results in successful playback?

5

@Volts I thought this issue was resolved with MakeMKV 1.15.4 but apparently not. Thanks for the link. It was insightful.

2 Likes
6

Investigating.

4 Likes
7

@geogan I can repeatedly replicate the issue in Black Hawk Down at the 14:36 timestamp. Can you provide some timestamps in some of the other titles? It would be helpful.

2 Likes
8

I’ve had this issue as well, but I’m not sure any streaming player can play these back without this problem.

My Zidoo Z10 Pro (not Plex) played all of these extended version MKV files fine with TrueHD/Atmos. No audio sync issue. While the Plient clients on my Shield Pro 2019 & Apple TV 4K 2021 have the audio sync issue. So, I don’t think that this is a MakeMkv issue.

1 Like
9

The only one I noticed myself so far was the Black Hawk Down audio problem.

The other movies were mentioned as having same problem by user AngryVirginian on MakeMKV forum.

I do have The Martian extended edition on 4K disc myself though and have also watched it previously using ripped MKV on PLEX but I didn’t notice any major obvious issues like the Black Hawk Down audio issues.

Not to say there aren’t any, maybe it did go slightly out of sync but I just didn’t notice. I suppose I could check it again at the extended scene changes (one major extended part in movie was the longer journey to the rocket from his base camp).

I don’t have the other 4K movies mentioned.

1 Like
10

Hello, I didn’t notice you were on this forum too. You mentioned on the other forum you saw problems with The Martian 4K. Do you remember where exactly you noticed it? Is it around where the extended scenes happen like when he went for longer trip in buggy near end of movie? Just interested to check if it also happens in my version of this movie I also use PLEX to play.

1 Like
11

IIRC, the issue happened all throughout the movie as it seemed like many scenes were extended. I remember that it started getting out of sync as soon as the crew minus Watney left Mars. For an easy check, forward to the 00:36:15 mark in the extended cut of the movie (2 hours 31 min). The sound will pause for like a second or two at 00:36:20 when Watney started talking to the camera.

1 Like
12

Confirmed just now AngryVirginian comment above. I get exactly the same sound drop and then go out of sync in Martian Extended at 00:36:20 when Watney says: “I’m gonna have to science the s##t out of this”.

Is there a bug fix for this in the works or coming?

1 Like
13

Bumping this because this is also an issue with Spider-Man: No Way Home. Super annoying.

1 Like
14

I just tried both my problem movies again there now - The Martian Extended @ 26:20 and Black Hawk Down @ 14:36

Both problems still exist - sound drops out and audio out of sync after these points.

PLEX Server: 1.26.0.5715
Client on Shield: 8.21.2.27212

1 Like
15

is this still being investigated? I just watched a rip of Moonfall. 1080P mkv with TrueHD, using the latest android plex beta client. I had to switch to DD 5.1 to get the audio to stop getting out of sync. I assume this is the seamless branching issue, same as I see in f9 and others.

1 Like
16

I am also having this same issue with The Martian Extended Version. The audio cuts out often, and when the audio comes back, it sounds different and is out of sync. You can fix it by pausing and playing or going back and forth.

I don’t have the issue with any other films - it appears to be because of the added scenes / audio branching.

1 Like
17

Also having this issue described by others with The Martian Extended Edition. Would appreciate any updates on potential fixes in Plex.

1 Like
18

Hi there, experienced this issue watching the Martian last night and it truly hampered the experience I had with Plex. I saw someone say they were looking into it but there was never a further response.

Please let us know that this is still an issue you’re looking into, as it’s easily replicated, a significant issue, and affects multiple users.

Reddit thread here: https://www.reddit.com/r/ShieldAndroidTV/comments/pvl6f7/atmos_audio_keeps_going_out_of_sync_in_plex/?utm_medium=android_app&utm_source=share

2 Likes
19

We are investigating the issue but it’s quite tricky as it seems the decoder on the device is playing back at the wrong speed which causes A/V to drift out of sync after a few minutes, and becomes worse as playback continues.

Would be good to confirm if anyone has seen the issue on a device that isn’t the NVIDIA SHIELD?

20

Well that isn’t anything like what is happening here. Sound/video are perfectly in sync (for possibly entire length of movie) until it hits one of these seamless branch points - then it instantly is 2 or 3 seconds out of sync for remainder of movie. There is no slow drift I see here at all.

1 Like