Hi!
I have a RPi3 + 5.1 USB DAC setup in my living room wich i recently updated from OpenElec 7.x to LibreElec 8.2.2. Since the update the DAC started to make strange crackling noises.
The pops seem to happen mostly when there is silence in the video i'm watching / music i'm playing.
I have tried everything that came to my mind to fix it but nothing helped. I have tested the setup with multiple different power supplies, another RPi3 board, an RPi2 model B and another SD card. I even tried connecting the DAC through a USB HUB.
I tried to load the snd_usb_audio kernel module with the parameter nrpacks=1.
I played with various USB kernel command line parameters that have been known to fix sound card issues in the past. Eg:
dwc_otg.fiq_enable = 0, dwc_otg.fiq_fsm_enable = 0 and dwc_otg.fiq_fsm_mask with all the possible combinations made the situation worse. Changing the dwc_otg.nak_holdoff value did not have an effect.
dwc_otg.speed = 1 seems to remedy the problem but makes the ethernet connection run unacceptably slow.
I also tried to change the CPU governor to "performance".
If i change the channel config in kodi to 4.0 the crackling stops but then i have no center/sub channel.
Setting anything else (fixed sample rate, keeping the audio device on, etc...) in the audio menu did not have an effect.
The audio codec and media source does not matter, it happens with flac, aac, and ac3, with local files and pvr.
The strangest thing is that sometimes the system just changes it's mind and theres no noise for 10-20 minutes then it starts again.
So far the only way i could stop the crackling without undesirable side effects was to downgrade to OE 7.0.1. That version works perfectly on the same hardware.
Details about my setup:
Sound card: Creative SB X-Fi 041e:30df Creative Technology, Ltd
lsusb -v pastebin: y3b1Ls8y
I run the RPi3 with stock settings, no overclocking. I use a clean LE install with "factory default" settings.
I found nothing in dmesg or kodi debug log related to the issue.
Any suggestions?