RPi4 testbuild with HD audio passtrhough (Atmos etc)

  • It seems we finally figured out all the missing bits and pieces to get HD audio passtrough working on the RPi4. Huge thanks go to popcornmix for taking care of the broadcom vc4 stuff!


    If you are in the mood for highly experimental, bleeding edge pre-alpha testing here's a build you can try:

    LibreELEC-RPi4.arm-9.80-devel-20200706110658-308adca.img.gz


    Please use a spare SD card and do a fresh install with the image. This build is based on LibreELEC master with Kodi 19, config.txt has changed and there's no easy way to go back to the stable LE 9.2 series except restoring a full backup.


    Also note that there are a couple of known limitations and issues with current RPi4 LE master builds:

    • No support for 4k output, this isn't implemented yet in the new driver. Neither is HDR output. Playing 4k HEVC files with HD output should work fine, though.
    • H264 hardware decoding is currently disabled as it can crash kodi when seeking or when playback ends.
    • Kodi 19 switched to Python 3 so be prepared that your favourite addons may not be available or work correctly.

    To get HD audio passtrough you have to enable it in Settings->System->Audio. Change the settings level to advanced or expert and then enable passthrough in general and the separate AC3, DTS, TrueHD and DTS-HD options (depending on what your AVR/TV supports).


    Also make sure you've setup your whitelist correctly and set "Adjust display refresh rate" to "on start/stop" or always in player->video settings to get smooth playback.


    As RPi4 HD audio is in a very early stage we'd be glad about any feedback - both working and non-working reports.


    so long,


    Hias

  • "No support for 4k output, this isn't implemented yet in the new driver. Neither is HDR output. Playing 4k HEVC files with HD output should work fine, though." - As you said this isn't working.

    Atmos works might fine. Actually sounds better on the Pi4 than it does on my Nuc. So I guess better audio driver?

    Only bug I had was with the scraper but that aint your fault. Probably set it up wrong.

    Everything I tried worked as expected.

    Even H265, 2160p (noticed it aint 4K since as you guys said :P)


    So I would say a success from me. I would love HDR to test as well in 4K, with this Atmos to see if they all play nice together.

    EDIT: Not sure if it's you guys or Kodi. But it mislable some Atmos as just "Dolby" but it's Atmos in the files.
    The LG SJ9 also start playing Atmos when you start it. So I guess it's a minor bug.

    Edited once, last by linuxares: Added info ().

  • Thanks a lot to all who tested (also LE staff and kodi forum users)!


    The RPi4 HD audio passthrough code has now been merged into the LibreELEC master branch so our latest (and future) nightly testbuilds on Index of / have this feature built in.


    I can't really comment on scraper / kodi label things (that's not my area of expertise), I mainly tested with various sample files in "Files" mode (not library) and that flagged both Dolby TrueHD and Atmos samples as "DOLBY-HD" (same for the DTS HD variants, that were flagged "DTS-HD").


    so long,


    Hias

  • I've been downloading the nightly versions through the week to see if I can at last get Passthrough on the HDMI2. Yesterday's brought success!! I've just installed it and now everything plays perfectly! Thank you so much for all the hard work gone into this! :)

    Edited once, last by armyofme ().