I’ve had this issue forever, but am buckling down and trying to fix it. On different TVs, with different HDMI cables, my Intel NUC (BXNUC10I3FNK1) with Plex HTPC will not play audio on any video when refresh rate switching is on. All kinds of audio I’ve tested work fine with it turned off. I have it plugged in directly to my Sony A80J.
Windows 11 is fully up to date on the latest stable version, drivers are fully up to date according to windows support assistant. Plex HTPC is the only thing on the machine, everything else is stock windows. The only settings change I made was to turn HDR on. The spec sheet says it has HDMI 2b, and I made sure I’m using an HDMI 2.1 cable I bought.
The UI also lags a lot, like a second on first key press and half a second of delay on subsequent presses.
Where do I even begin with troubleshooting this? Is there anything I can do?
beautiful setup. i’d use a certified ultra high speed hdmi cable
pms db gigantic and unoptimized can lag htpc
reboot the nuc
demonstrate audio loss for 30 sec in htpc
quit htpc and grab logs.
copy and paste the mediainfo for that file into your reply, in a code block </>
Tell us your PMS version you can find in Plex for Windows: Settings → Server → General
Good note, I run PMS on a Synology NAS — the NUC is only for playback.
I tried three times, once to show it working, and one to show it failing with HW acceleration both on and off. I had issues with HW acceleration in the past, but it doesn’t seem to affect this issue. I realized I didn’t let it play for a full 30 seconds but if that matters I can try again.
I’m including server/client logs here, the media info of the video (I tried a few different audio types I could find but the behavior was the same on all of them)
This is typically due to devices not being ready immediately when a refresh rate (or HDR) switch occurs. If the audio device is opened while the device on the other end of the HDMI cable is not yet read, this can result in no audio. The fix is to increase the value in the Refresh Rate Switching Delay setting.
yup, that was it, thanks! Is there any further reading on why this happens? I’m assuming this isn’t really something one can “fix” to remove the delay.
When you change refresh rates, HDMI devices downstream of the computer tend to go through a process of detection of the new input signal. In some cases, this can result in the device behaving like it has been disconnected and reconnected. I’ve seen cases where the application’s logs indicate the removal and then addition of the HDMI audio device (which is likely what occurred in your case). Obviously if playback were to try to open an audio device which has been removed, it will not work and you will not have any audio.
The delay, and how long it should be, depends on the devices you have connected downstream on the HDMI. This is one of the reasons why most consumer devices don’t have the option to match the refresh rate with the frame rate because it invariably contains this tradeoff that the consumer must deal with and it’s usually easier to not give consumers the option rather than have to tell him how to setup all the pieces.
