ZDF Mediathek - Sound out of sync

  • Hello,

    I installed the ZDF Mediathek Add-on (V5.0.2) and the ARD Mediathek Add-on (V6.0.0) on a fresh install of LibreELEC-RPi4.arm-9.95.5. Nothing else is installed, and the only settings I changed were for screen resolution (4K, 30Hz) and adjustment of the screen size. The sound I get when playing any content from the ZDF Mediathek is out of sync, whereas ARD Mediathek works (as far as I observed).

    I run the ZDF mediathek Add-on (V5.0.2) on a desktop (Debian Buster) with Kodi 19.1 (from Buster backports) without any sound problems, and when running the plugin on my previous install of LibreELEC 9.2.6 on the same RPi4, sound was in sync, too.

    Would there be any hints in the log files that could indicate the reason of the problem?

    Best regards,


  • Thanks a lot for pointing this out. I did not know that repo. Before installing "ARD und ZDF" I had already upgraded to LibreELEC-RPi4.arm-10.0-nightly-20210711. But even with the nightly build and "ARD und ZDF" the sound is out of sync. I also had the sync problem with a file downloaded via MediathekView (but from ARD), which is why I tried the nightly build.

    Should I submit a bug report?

  • I am not sure if the problem is caused by the Add-on. As I said I also had problems playing back a file I had downloaded before via Mediathekview. And the Add-on works well on my desktop. I will try a few more things and then submit a bug report in one of the forums...

  • To my knowledge, ARD and ZDF use different sources for playing on smartphone and desktop. So the out-of-sync add-on may uses the smartphone source. Check whether your downloaded out-of-sync file works on your desktop PC. If it's also out-of-sync there, blame on the content provider (ZDF).

    DNB music-addicted finger drummer.

  • It seems that the reason was the DRM Prime decoding that is active by default in LibreELEC. When I turn it off, all sync problems I had observed disappear. Moreover, with DRM Prime turned on, the image was slightly squeezed horizontally. I.e., I got black bars on the left and the right when playing back 16:9 content. The Kodi GUI did not show any black bars, and when turning off DRM Prime decoding, the black bars disappear, and the image has the right proportions.

  • I have just tried again with LibreELEC-RPi4.arm-9.97.1. The problems persist if using "Directly to plane" (not sure if this is the correct label, my system language is Portugues), but DRM Prime in EGL mode seems to work fine.

  • Is it still in-sync when switching off DRM Prime on LE 9.97.1?

    DNB music-addicted finger drummer.

  • Yes, it is in sync. I also noticed that DRM Prime is not switched on by default in LE 9.97.1. The problems (sync and aspect ratio) only occur with DRM Prime with the setting "Directly to plane". But I did not do any proper tests. Just gave it a quick try.