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Audio dropouts with 4k @ 60hz refresh
#1
Hello everyone,

I am new to Kodi so please bear with me.

I have just installed the latest version (17.1) of Kodi through LibreELEC (8.0.1) on my new HTPC. I have run into a problem and I asked first on the LibreELEC forum but have got no responses so far.

My HTPC is an Intel Core i7 (Kaby Lake) system on an Asrock z270-fatal1ty ITX motherboard. The board has built in HDMI 2.0 output with onboard Intel HD 630 Graphics.

The HTPC is connected to my Denon AVR-X6200 via HDMI. All inputs on the receiver are HDMI 2.0a and HDCP 2.2 enabled and will pass 4k @ 60hz. The receiver is connected via HDMI out to my LG OLED55B6V television which is 4k @ 60hz compatible.

The issue that I am having is that, when Kodi on the LibreELEC install is set to output to the display at 3840 x 2160 at 60hz refresh rate, I get regular audio dropouts which are like a little pop in the sound and sound stops for half a second before it returns. This happens once every minute or so. The picture on the TV is unaffected and looks fine always. You can also hear the audio pop or click when there is no file playing.

I played around with the settings, such as disabling the option to adjust refresh rate and disabling audio passthrough, but this made no difference.

Then I found that, if I dropped the refresh rate setting down to 30.0hz from 60hz, the audio plays fine with no issues. I only have a few options in the menu for refresh rate in LibreELEC and 30hz is the next lowest available before 60hz. The audio drops out on both music files and video files at 60hz refresh but is perfect at 30hz refresh rate.

I then wiped my HTPC and installed Windows 10 with Kodi 17.1 to see if this was LibreELEC-related or a Kodi problem. I experienced the same pop and audio drop regularly running under Windows as well with output set to 4k @ 60hz. It was once again fine at 30hz.

I then tried connecting the HTPC directly to my TV rather than through the receiver. This works without issue - there are no audio dropouts at 4k with 60hz in this configuration.

So it seems to be a generic problem with Kodi communicating over HDMI to my receiver. I would like to get the setup working through the receiver in order to use passthrough and playback of multi-channel sound (the Intel audio driver under Windows with the HTPC connected direct to my television was limited to stereo playback.)

Can anyone help?

My debug log is here: http://sprunge.us/RWYB

The log is from the LibreELEC installation rather than the Windows one.

Many thanks in advance for any help.
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#2
I have a similar setup but don't have a 4K display yet. I know when I did my initial research that the converter chip on the ASRock motherboard that bridges the Displayport over to the HDMI port (which gets you HDMI 2.x on the HDMI port) isn't that great. If you have a little money, you might try to find a decent DisplayPort to HDMI converter and use the Displayport instead. That would eliminate the onboard conversion chip (but introduce a new external one in the dongle).

It might not change anything, but at least it would tell you something.
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#3
Thanks for the reply - very interesting.

I have ordered a Plugable Displayport to HDMI 2.0 dongle now - http://amzn.eu/czJYZrJ

I will see how that performs and if the audio dropouts with 4k @ 60hz resolution are solved.

Unfortunately I haven't been able to find any information about the conversion chip which is used in this dongle. Hopefully it is a different one to that on the ASrock motherboard.

I'll update this thread with my findings when the new adapter arrives.
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#4
This is a follow-up just in case it helps other people on the forum.

I received my Plugable Active Displayport to HDMI 2.0 adapter in the post this morning.

I connected the adaptor to the Displayport socket on the back of my HTPC and ran it through my Denon AV receiver as before.

I can confirm that the audio dropout issue that I was having in 4k resolution at 60hz refresh rate is now gone. Video and audio both play perfectly on these settings using the new adaptor.

Plugable have told me that the chip which does the DP to HDMI conversion in their adaptor is the Parade PS176 chipset (https://www.paradetech.com/products/ps176/).

Thanks for pointing me in the right direction, @pkscout.
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#5
I know it is an old post. This really fixed the audio dropout in my intel NUC when set to 4K60hz and used HDMI connection. In my case, I tried a usb-c to HDMI adapter which works with no audio dropouts. This was really frustrating as I had to use 30hz to work around this issue until now but live ESPN stream (uses 60 fps) would have a choppy video.
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Audio dropouts with 4k @ 60hz refresh0