Carey, I share your feeling on ROCK64, only I've never experienced kernel panic. I bought my ROCK64 SBC in 2017. FYI, the board marked ROCK64 2,0 2017-0713 with date code 1704. There is no eMMC and I used only 16GB microSD card. I got the same 5V3A AC adapter as you did, together with the remote control from PINE64.
I experienced with kernel 4.4.156, heavy stuttering during playback of 720p and 1080p HEVC (8-bit or 10-bit) video files. Every 10 or 15 seconds, the video freezes for a few seconds and then playing catch up. Then the same thing repeats itself again while audio is fine. The last good (or less problematic) kernel was the one released on 2018/10/02.
Would it be the hardware problem? AC adapter (voltage unstable)? Processor temperature too high due to heat sink too small? I don't think so. In fact before LibreELEC official release, I was testing Raybuntu's ROCK64 build and that was good at least for video playback. After I read your post, I pull the image file out and test it once again on the same hardware and playback was smooth, no stuttering or audio out of sync at all for the whole movie. Color is also very good.
I still keep the image file of the last build by Raybuntu LibreELEC-rock64.arm-rb-leia24.img.gz but only the tar file (for update) of 2018-10-02 LibreELEC-RK3328.arm-9.0-nightly-20181002-8b3e678-rock64.tar, you can download from here and test them on you SBC if you like.
I also tested the image that Kwiboo suggested with kernel 4.9 or 5.0, If I turned on HW acceleration, video was not playing at all but audio was fine. If I turned off HW acceleration, video was playing significantly behind the audio but no stuttering. All tests were done with the same video 10bit HEVC 1080p video file on the same SBC hardware.
I had the same issue. I purchased a ROCK64 SBC last year and it's marked ROCK64_V2.0 2017-0713, same as yours. I did my setup around September 2018 by using a nightly build which unlikely I did not backup, actually I performed a backup through the LibreELEC UI to find out too late that it backed up the storage partition only. So everything was working fine until last Monday when I had the very bad idea to upgrade LibreELEC. Since then I started to experience the same issue as you: every 10 or 15 seconds, the video was freezing for a few seconds before re-syncing. The strange fact is that this behavior was taking place only after I stopped a video and restarted the playback; if I just let a video play after the boot without stopping it there would have been no issues. However, I tried to downgrade to the older official release which is
LibreELEC-RK3328.arm-8.90.006-rock64.img and I had the same issue. It runs kernel 4.4.154. Then I found your post and I tried the
LibreELEC-RK3328.arm-9.0-nightly-20181002-8b3e678-rock64.tar image you uploaded which solved the issue. Now the playback is smooth as before. As you pointed out it looks like that with the later kernel or DTB they broke support for the older versions of the board.
For completeness, attached the kernel log messages printed during a playback freeze event.
Thanks for having uploaded that build.