Multithreaded SW decoding on rpi

  • Hi,

    I downloaded LibreELEC-RPi4.arm-9.2.0.img.gz on my rpi4, and it's working fine of course. However; as the pi does not support H.264 10bit decoding in HW, it does this in SW. Strangely enough, it does this in a single thread (the other 3 cores are idle). This is a pitty, since my 1080p sample -just- does not play fluently enough, while it otherwise would have no issues with all cores decoding.

    From what I pick up from [VideoPlayer] multithreaded AV1 SW decoding does not work / always falls back to a single thread · Issue #15893 · xbmc/xbmc · GitHub and elsewhere is that there is possibly some bug that if HW support is attempted first and then the code falls back to SW, it always runs single threaded. (In older non-pi versions ppl actually recommended fully disabling HW decoding to have multicore SW decoding; but this option is not available on the libreelec build) Does this sound familar to anyone? I think this would be a major improvement for the SW decoding performance on the pi.


    Note, oddly enough, the raspbian buster kodi release from Rascas/Diogo (18.4) -can- play the file fluently, IF omx decoding is enabled and MMAL decoding is disabled (although with a reduced quality in colors). As libreelec does not have the omx-option anymore, we have to do the "correct" SW decoding, but then I hit the performance issue.

    Thanks for any feedback!