Red/green dots and artifacts while playing video

  • Hi.

    I use Raspberry Pi4 2Gb.

    When I started to play any video (for example, info from VLC about codec for one of files: H264 - MPEG-4 AVC (part 10) (avc1)) I see red/green dots and artifacts over all screen, see photo.

    Kodi interface works perfect, issue only while playing video.

    Issue reproduces on LibreELEC-RPi4.arm-9.95.1, LibreELEC-RPi4.arm-10.0-nightly-20210320-e367b4a, LibreELEC-RPi4.arm-10.0-nightly-20210313-c5d7822

    Issue does not reproduced on nightly build dated about 20201120. Unfortunately, I deleted image with this version and can’t roll back to it.

    Thanks!

  • Would you be able to upload a sample video file that produces this problem?

  • ffmpeg -ss 00:00:42.0 -i original.mkv -c copy -t 00:00:25 sample.mkv


    is the command I used for sample .


    00:00.42 is start time, 25 is length.

  • Would you be able to upload a sample video file that produces this problem?

    Sure!

    sample.mkv

    I can reproduce this in every video file I have.


    ffmpeg -ss 00:00:42.0 -i original.mkv -c copy -t 00:00:25 sample.mkv


    is the command I used for sample .


    00:00.42 is start time, 25 is length.

    Thanks!

  • I couldnt see anything weird with that clip on my rpi4 using beta1. could you post a screenshot so I know exactly where to look?

  • I don't know how to take screenshot

    Attach a USB keyboard. Press the PrtScr button, and find the screenshots folder in the LibreELEC storage.

  • heh, that was some serious artifacts, but since I dont get those on same hardware. are you able to try with another hdmi cable?

  • Attach a USB keyboard. Press the PrtScr button, and find the screenshots folder in the LibreELEC storage.

    Thanks, it was pretty obvious.


    Unfortunately all I got - black screen on screenshots:


    And, btw, Kodi interface (progress bar, buttons etc) displays without issues on my TV.

  • heh, that was some serious artifacts, but since I dont get those on same hardware. are you able to try with another hdmi cable?

    No, I don't have another mini/micro HDMI cable.

    But I don't think this is cable issue, more likely HW decoding problem since all Kodi interface displays without issues on my TV while video plays with artifacts on background.


    Last stable (9.2.6) don't work correct for me, november nightly works fine, current nightly and beta - also with issues.

    Is there any place with older nightly builds, dated around november 2020?

    And maybe its worth check how it works without HW decoding? (But I don't know how to disable it)

  • Attach a USB keyboard. Press the PrtScr button, and find the screenshots folder in the LibreELEC storage.

    Unfortunately this does not work on LE 9.80 / 9.95 / 10 Nightly anymore - only Kodi menu can be saved currently. Perhaps in future this will be supported again.

  • > Issue does not reproduced on nightly build dated about 20201120.


    HW hevc decode may not have been supported back then, so you may have always had this issue.

    I'd predict that disabling DRM Prime HW decode in settings would avoid the artefacts.


    It is possible you have a hardware fault. You don't have another Pi4 you could try the sdcard on?

  • > I'd predict that disabling DRM Prime HW decode in settings would avoid the artefacts.

    Yes!

    Disabling this setting fixed issue.


    > It is possible you have a hardware fault. You don't have another Pi4 you could try the sdcard on?

    Unfortunately no. But disabling DRM Prime HW decode is acceptable fix for me now, I guess.


    Thanks a lot for help!