Random Kodi freezes on Rock64

  • Hi. I hope this is the right forum to post this. I've read other posts about freezing, but most of these seem to be at startup.
    My problem comes intermittently after many minutes of playing perfectly, and only manifests itself on some of my Rock64 players.

    I have 10 of these players for a low cost 4k video player for my local charity Haunted House.
    7 of them run flawlessly for many hours.
    Of these, 2 of them froze once, but seem to have been fixed simply by cloning a "good" SD card and restarting.
    But, one of them keeps freezing, and replacing the SD card with a new copy does not fix it.

    The freezing time is somewhat random, from 20 minutes to 120 minutes.

    The video freezes on an image in a random location in the middle of the video file.

    Mouse movements to not make the menus pop up.

    I can still SSH and FTP to the device.

    I am running LibreELEC/Kodi on a 4 GB Rock64 and I occasionally get freezes on one of 10 Rock64s that I am running.

    LibreELEC 9.1.002

    Confluence skin

    It's a 4k video, playing on a 1080p monitor for debugging. The freeze happens both in 1080 and 4k.

    The CPUs have heatsinks with cooling fans, and run at 43 deg C. CPU cores show <20% loading in general. Memory use is ~0.4GB (10%)
    It plays one video file that is on the SD card, and I am using SanDisk Ultra microSDHC UHS-1 cards that claim to be good to 80 MB/s
    I have 3 Amp power supplies.

    My Kodi runs with a addon which seeks back to the beginning after ~180 seconds. It also seeks to different locations based on GPIO inputs.

    I have disabled SAMBA, but left the other default addons enabled.

    I've uploaded the log files from a good run to http://ix.io/1xek

    If you search for "hhloop", you will see a few "normal" sequences when the player seeks to 0.

    From a bad run, the log file showed one extra line after a normal loop sequence.

    ERROR: ffmpeg[E2E2C380]: [AVBSFContext] Channel mapping 2 is only specified for channel counts which can be written as (n + 1)^2 or (n + 1)^2 + 2 for nonnegative integer n

    Can anyone make any suggestions on what I can try next?

    Thanks

    Edited once, last by JeffR: Typos. (September 28, 2019 at 1:31 PM).