2018-09-14, 05:24
No worries.
I found the root cause for this 1080p video stutter in Kodi after switching the refresh rate. Mi Box’s refresh rate switching is flawed. It only changes the video output refresh rate, but the interface refresh rate remains the same until you reboot. You can verify this with AIDA64, TVHZ, Smart YouTube TV, Kodi or any other apps that can show you the interface refresh rate.
We know that the Android has two resolution, one for video output and one for the interface. It looks like refresh rate is the same.
This behavior will affect the device in two folds:
1) User Interface
If you boot up at 24hz and later change to 60hz, your system and app interface will be stuck at 24hz and sluggish, until your reboot;
If you boot up at 60hz and later change to 24hz to watch some movies, you interface will be slowed down as the system and apps still think it is at 60hz while video output is only at 24hz.
2) Playing Videos
Many video apps are seemingly unaffected by this issue, such as VLC. I guess they render the video directly to the video output with MediaCode(Surface) hardware acceleration, thus match the correct refresh rate set by you.
However other apps, noticeably the mighty Kodi family, does not play well with it. If you boot up your box at 60hz, and switched to 24hz to play some 1080p@24fps movies, Kodi seems trying to smooth the video into 60fps, thus produces severe stutter as video output is only 24hz. It does not happen on 4k@24fps video though probably because it is too costly to smooth it. Now if you reboot your box with 24hz settings, the 1080p@24fps video will play smoothly. However, Kodi now is going to play every video, including 4k@60fps ones, at 24fps! Changing the refresh rate in settings will not work, until you reboot.
Now who should I report this issue to? Kodi or Xiaomi?
TL;DR: If you like to manually switch refresh rate to match your video content, but then notice frame skip and stutter in Kodi or other apps, try reboot your device with the matching refresh rate. Hopefully this will be fixed by Xiaomi or Kodi soon along with auto switching.
I found the root cause for this 1080p video stutter in Kodi after switching the refresh rate. Mi Box’s refresh rate switching is flawed. It only changes the video output refresh rate, but the interface refresh rate remains the same until you reboot. You can verify this with AIDA64, TVHZ, Smart YouTube TV, Kodi or any other apps that can show you the interface refresh rate.
We know that the Android has two resolution, one for video output and one for the interface. It looks like refresh rate is the same.
This behavior will affect the device in two folds:
1) User Interface
If you boot up at 24hz and later change to 60hz, your system and app interface will be stuck at 24hz and sluggish, until your reboot;
If you boot up at 60hz and later change to 24hz to watch some movies, you interface will be slowed down as the system and apps still think it is at 60hz while video output is only at 24hz.
2) Playing Videos
Many video apps are seemingly unaffected by this issue, such as VLC. I guess they render the video directly to the video output with MediaCode(Surface) hardware acceleration, thus match the correct refresh rate set by you.
However other apps, noticeably the mighty Kodi family, does not play well with it. If you boot up your box at 60hz, and switched to 24hz to play some 1080p@24fps movies, Kodi seems trying to smooth the video into 60fps, thus produces severe stutter as video output is only 24hz. It does not happen on 4k@24fps video though probably because it is too costly to smooth it. Now if you reboot your box with 24hz settings, the 1080p@24fps video will play smoothly. However, Kodi now is going to play every video, including 4k@60fps ones, at 24fps! Changing the refresh rate in settings will not work, until you reboot.
Now who should I report this issue to? Kodi or Xiaomi?
TL;DR: If you like to manually switch refresh rate to match your video content, but then notice frame skip and stutter in Kodi or other apps, try reboot your device with the matching refresh rate. Hopefully this will be fixed by Xiaomi or Kodi soon along with auto switching.
