Many freezes in the Terminator 2 UHD Version

Hi @sam_nazarko!
I have many freezes in Terminator 2 with the Vero 4k - playing a untouched rip (no reencode) from my Synology NAS with kodi nfs mounted (cannot use fstab because of my iPads) - this is the first movie with problems after you made some improvements for UHD playback, all other movies i have seen works fine (Serenity, John Wick 2, etc…)… to proof that the file is ok i made a test with my HiMedia Q5 and the movie plays fine without problems!

Here are some needed information:

Unique ID : 140569139895022250878275911340914674331 (0x69C0A1AF1980BEEEB5CC00D047F08A9B)
Complete name : V:--=UHD=–\Terminator 2 - Tag der Abrechnung (1991) tt0103064 uhd bluray\Terminator 2 - Tag der Abrechnung (1991) tt0103064 uhd bluray.mkv
Format : Matroska
Format version : Version 2
File size : 47.8 GiB
Duration : 2 h 17 min
Overall bit rate : 49.9 Mb/s
Encoded date : UTC 2018-01-06 14:15:20
Writing application : MakeMKV v1.10.8 win(x64-release)
Writing library : libmakemkv v1.10.8 (1.3.5/1.4.7) win(x64-release)

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
Duration : 2 h 17 min
Bit rate : 47.0 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) : 0.236
Stream size : 45.0 GiB (94%)
Writing library : ATEME Titan File 3.7.10 (
Language : English
Default : No
Forced : No
Color range : Limited
Color primaries : BT.2020
Transfer characteristics : PQ
Matrix coefficients : BT.2020 non-constant
Original source medium : Blu-ray

ID : 2
ID in the original source medium : 4354 (0x1102)
Format : DTS
Format/Info : Digital Theater Systems
Format profile : MA / Core
Codec ID : A_DTS
Duration : 2 h 17 min
Bit rate mode : Variable / Constant
Bit rate : 2 919 kb/s / 1 509 kb/s
Channel(s) : 8 channels / 6 channels
Channel positions : Front: L C R, Side: L R, Back: L R, LFE / Front: L C R, Side: L R, LFE
Sampling rate : 48.0 kHz
Frame rate : 93.750 FPS (512 SPF)
Bit depth : 16 bits
Compression mode : Lossless / Lossy
Stream size : 2.80 GiB (6%)
Title : Surround 7.1
Language : German
Default : Yes
Forced : No
Original source medium : Blu-ray


I made a videoclip from the first freeze - as you can see that the aq falls in seconds to zero %

Vero4k - T2 Problem


I’m not sure why your iPad would prevent you from using fstab mounts. If you use Kodi on your iPad you can use path substitution.

  • Can you try with an fstab share without library mode just to check playback?
  • If that still fails, try local playback from a USB drive.

This will let us work out if there’s a playback issue in your environment, or simply a throughput issue.



Hi @sam_nazarko!
I have fstab configured as fallback and play the movie via fstab without the ember plugin - same problem, same scene - picture is freezed, ag falls to zero %
I cannot test it with an usb stick or disc, haven‘t a stick with 50gb!
The other Mediaplayer use the same environment (Receiver, Switch, NAS) so it‘s not a network related problem!


Don’t know if it helps but I had similar issues with Dredd which requires 90MB bandwidth.

Other 4K films were less bandwidth demanding.

Could not use wifi AC (unstable anyway), lan port was not able to cope so I added a USB 3 /Gigabit Lan adapter.

Obviously since USB ports are USB 2 you never reach 1Gb but it was enough to unfreeze Dredd

I have an usb 3 lan adapter also to made a test, doesn‘t help - same freeze occurs!


I watched the video. Looks like the decoder chokes due to a scene change.


echo 16 | sudo tee /sys/module/amvdec_h265/parameters/dynamic_buf_num_margin

via the command line.

Note that this isn’t persistent, so if you reboot, you’ll need to re-apply this. This is just for testing purposes however.

We increased the dynamic buffer margin in the last update which resolved playback issues with some titles. However, we tried to increase it by as little as possible because increasing it too much can cause slowdowns when seeking and also sometimes issues with pull-up correction.


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This helps, the freezes are gone - watch 5 minutes without any freezes but slowdowns when i jump to another chapter so i test some other settings and it seems that echo 12 solve the freezes and i have no problems when i change to another chapter…
So is there any chance to set this as standard in a test build or the next update?


The idea was to start with 16 and then work out an acceptable value. It looks like 12 will suffice for this.

I’ll make this available in the next update.


You can just add this to your /etc/rc.local to make it permanent:

echo 12 > /sys/module/amvdec_h265/parameters/dynamic_buf_num_margin

Better to keep the buffers at 12, which I’ve now done here:

Thanks @MikeDelta for testing and confirming.

Thanks again for your exzellent and fast support! :blush:

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