network frame sync

    Hello,
    thanks a lot for libreelec , it works like a charm here.
    i used to sync displays via omxplayer and osc udp , but made the change to be able to output 10 bits 4k H265 with aac audio.

    i made shell scripts and am currently using kodi callbacks to link multiple players ,
    but sync is soso , with high latency compared to what i had before.
    any hints ?

    did someone tried something in this area ?
    Have a nice day.

    Py

  • Go to Best Answer

    i wasn't very precise :
    i am on a network of raspberry pi 4 with librelec 12.0.2 iirc
    there is a router with dhcp on the network , but ip are fixed, and all machines are on the lan side of it.
    i play local files that are on each pi, of synchronised loops
    i get low values for ping ,

    removed buffering , but still have a fluctuating start time ( different when pointer is displayed than when in "full screen"

    thanks for any help. it would be a great anbd cheap solution for artists.


    just an update /
    i tried to send commands from kodi-send and via curl and json rpc .

    i get some variable delay on this setup:
    i tried to remove every protocols smb , bonjour , since i am on a lan without router now , just fixed IP adresses)

    i made a master that only plays sound and sends commands and two slaves : identical setup.
    i still get a variable delay , between 1 frame most of the time to sometimes 10 or more ...

    what could introduce some variable delay ? ping is very low, (0.3ms)

    hello, thanks for your reply

    yes,synchronous playback of multi screen projection (artist movie made for two screens)

    and i somewhat i managed to do it (since yesterday ) , but only if sound is removed from the video file.
    it seems a lot of things happen on hdmi for handshake of sound equipement ( buffering+ ??)

    i was using passthrough for sound on hdmi to a audio toslink extractor , it seems it was the source of my problem .
    now i can get two videos playing synchronously.
    a third raspberry will read ambient sound . ( almost synched ...)


    i used kodi callbacks addon , bash scripts, and had to struggle a bit.
    but now i know it's possible.
    just has to be improved .
    if you know places where i can reach other people, i am sur i am not the first one to try this ..

    Quote from py9399

    i have to edit config.txt to be able to use analog audio ?

    Correct.

    Quote from py9399

    does this provide a predictable, repeatable delay ?

    Probably..

    Quote from py9399

    if you know places where i can reach other people, i am sur i am not the first one to try this ..

    I don't recall anyone doing something similar with LibreELEC before; probably because we are intentionally a 'dumb' client/playback oriented distro. I would expect to find people doing more complicated projects in the Raspberry Pi forum, or if the solution is built around Kodi, perhaps the Kodi forum.