[manhas]

Device: Apple TV 4, tvOS 10.0.1
Kodi: 17.0-BETA5 Git:2016-11-08-73aa459
Log: https://paste.ubuntu.com/23522728/

Issue:
When using 50 Hz refresh rate (both 1080p and 720p resolution) set in the Apple TV settings and "Sync playback to display" turned on in Kodi, the audio stutters once every second or so, there is also intense video jitter noticeable. This happens for both 23.976 FPS and 25 FPS videos.

25 FPS videos are played smooth at 50 Hz with "Sync playback to display" turned off which is expected. But when turned on there is both audio stutter and video jitter which I don't understand since there is not adjustment needed for the video to match the display.

When using 60 Hz refresh rate the audio is fine and both 23.976 FPS and 25 FPS videos are played smooth (at least smoother than when turned off). So this only happens when using 50 Hz. I've tested on two different ATV4 devices against two different TV sets, same result.

[DanTheMan827]

I would try the latest tvOS alpha that Memphiz just released today.

From what I can gather it appears that hardware decoding has been added.

[manhas]

The latest tvOS build with hardware decoding didn't change anything, but perhaps it will help with another playback issue I've experienced that's more random, ATV4 Playback is sometimes choppy?.

I don't know what's what in the Kodi logs, so I might be completely wrong here. But it looks like Kodi detects 60 Hz refresh rate when ATV4 is using 720p/1080p at 50Hz. Is it possible to force/tell Kodi that it's 50Hz it should try to adjust to regardless of the detected refresh rate using advancedsettings.xml?

From the log when using 50 Hz refresh rate:

Code:

17:06:45 T:6141145088   DEBUG: CVideoSyncIos::GetFps Detected refreshrate: 60.000000 hertz
17:06:45 T:6141718528  NOTICE: Creating InputStream
17:06:45 T:6141145088   DEBUG: CVideoReferenceClock: Detected refreshrate: 60.000 hertz

[manhas]

I've played around trying to have ATV4 and Kodi play without jitter for both 25 FPS and 23.967 FPS content without having to switch the refresh rate in settings, but no success yet. I know it's ATV4 fault and perhaps my TV, but I'm hoping there is a possible workaround.

Here's what I'm experiencing:

with 1080p@60Hz with "Sync playback to display OFF":
- 23.967 FPS video is played smooth when using a TV film setting.
- 25 FPS video have very noticeable jitter.

with 1080p@60Hz with "Sync playback to display ON":
- 23.967 FPS video is played smooth when using a TV film setting.
- 25 FPS video have a small but noticeable jitter.

with 1080p@50Hz with "Sync playback to display OFF":
- 23.967 FPS video have very noticeable jitter.
- 25 FPS video is played smooth.

with 1080p@50Hz with "Sync playback to display ON":
- 23.967 FPS video is played smooth when using a TV film setting (I don't see any difference compared to using 60Hz), but the audio stutters every 1-2 second.
- 25 FPS video have a small but noticeable jitter, but the audio stutters every 1-2 second.


So I'm not able to get perfect playback for 25 FPS videos using 60 Hz regardless of the settings. But when using 50 Hz I get smooth playback for 23.967 FPS with "Sync to playback to display" turned ON except for the audio issue, and for 25 FPS I get smooth playback with "Synch playback to display" turned off. So if the audio issue was fixed for me and I was able to automatically turn "Sync playback to display" ON/OFF based on the video FPS, I think I should be able to get smooth, jitter free playback for both 23.967 and 25 FPS videos.


So two questions based on this:

1) Any idea why and how to fix the "audio stutters every 1-2 seconds" when using 50 Hz and "Sync playback to display" turned ON?
2) Is it possible to set "Synch playback to display" based on the video FPS, have it automatically turned on for 23.967 FPS videos and turned off for 25 FPS videos without me needing to toggle it in settings?