Audio Distortion LE9 and LE10 on Passthrough when reconnecting

1st Official Post

    I have had an issue that has been persistent for several years and I have been unable to understand the cause or find a solution.

    Issue:

    Whenever I turn on the Preamp/Amp/Projector, the pass-through audio is distorted. If I reboot the HTPC, the audio is restored and works flawlessly, unless I power on/off the rest of the system.

    • distortion noticeable on default kodi navigation sound, audio freq shifts up and crackle distortion
    • distortion present if trying to play media
    • Reboot system after Preamp/Amp/Projector are power up and audio is corrected
    • Logs: http://ix.io/3uA0

    HTPC:

    • Intel I3-7100
    • Gigabyte GA-H270M-DS3H Motherboard
    • 16GB DDR
    • Silverstone ST455F Power Supply
    • ADATA Premier 600 64GB SSD
    • Clean install of LE10 RC5 Build currently loaded (Same issue with last 5 versions of LE9)
    • All format for audio set to pass-through
    • No audio plugins added beyond base install with LE image

    System:

    • HDMI from HTPC to Anthem AVM60
    • 1000BaseT Ethernet from HTPC to Cisco SG200-18 Switch
    • All Media on Server Connected to Cisco Switch (Proxmox Server, NFS Share)
    • DB on Server Connected to Cisco Switch (MariaDB CT on Proxmox Server)

    I believe there is something going on with the ALSA setup but despite several attempts over the years I have not been able to correct this. My hope was it would be corrected with Kodi 19 (LE10) but right now I am not seeing any change. Any guidance would be appreciated.

    Thanks!

    • Official Post

    For HDMI devices the audio output properties in Kodi are determined from EDID data read (once) at boot time. Modern AVRs pass-through the EDID from the downstream HDMI device, e.g. projector or TV, so I'm wondering if the HTPC is reading EDID data from the AVR itself (as the projector is not on) and then after turning it on the HDMI properties change and cause some issue.

    Have a look at the EDID output from "modetest" after boot with the project off, then reboot with it on. If it's changing .. follow the instructions in the wiki to capture and use a static EDID file so the HTPC always sees the projector as on (with the right EDID data).

    No guarantees that's the issue, but we do see odd things when people turn things on after the HTPC sometimes. It's just a hunch.

    I think you found my issue, though not what was expected.

    Modetest returns no devices. I suspect that is what is causing the issue, though it does not answer why HDMI works, it would answer why it does not maintain sync after power cycle.

    Now to find out why the HDMI is not recognized

    Quote from mglae

    Generic is using X11. Try xrandr instead.

    Thanks, that worked, will see if I get a change during power cycle and try out the EDID fix.

    I tried several changes in the Bios based on some other threads/forums, did not give positive results.