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It should be mutually exclusive in theory. I'm not entirely sure myself, but a guess would be that if the TV refresh rate can't be changed, then it falls back to changing the video FPS to match the current refresh rate?
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2015-03-02, 15:28
(This post was last modified: 2015-03-02, 15:29 by Memphiz.)
its not mutually exclusive - playing a 23.967fps movie with a tv which only supports 24hz will switch it to 24hz - sync to display will adapt for the rest
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noggin
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2015-03-02, 15:46
(This post was last modified: 2015-03-02, 15:48 by noggin.)
No - not mutually exclusive.
"Adjust Display Refresh Rate" will switch the output refresh rate when playing back a file to the best refresh rate that is supported by the display AND the hardware Kodi is running on (as reported by EDID) If you don't select this option then you output at a fixed display refresh rate, which is usually set in Settings->System->Video Output. This setting allows Kodi to change the frame rate of the video output fed to the display, to ensure the best refresh rate is selected.
So if you have a display that supports 50Hz and 60Hz content, 50Hz content will be output at 50Hz and 60Hz content at 60Hz, however 24Hz will be output at 60Hz with 3:2 (ignoring 1000/1001 refresh rates (*))
If you have a display that supports 24Hz, 50Hz and 60Hz content, then 24Hz will be output at 24H, 50Hz at 50Hz and 60Hz at 60Hz. This is great if you have a display and hardware that copes with everything flawlessly.
"Sync Playback to Display" is different. It alters the playback speed so that it matches the display refresh rate (which could be fixed or could be variable if you have also selected Adjust Display Refresh Rate)
Why is this useful?
Say you have a 50Hz display but 24p content. 24p content will look horrible if you play at 50Hz, but if you Sync Playback to Display it will play the 24Hz back at 25Hz which will look much nicer at 50Hz. (Even if you have a display that syncs to 60Hz and could watch 24p material with 3:2 - which is nicer - you may still chose to watch at 50Hz with speed up and 2:2 to avoid the 3:2 judder. I sometimes do.)
Also - if you have a Kodi platform that can't cope with 23.976Hz output, but it can cope with 24.000Hz, you would normally get a repeated frame every 40" or so to keep stuff in sync. However if you also select Sync Playback to Display then Kodi will slow speed up the 23.976Hz content to 24.000Hz - so no repeated frames (and thus no stutter) but you then have to sort the audio sync out (either by resampling or by dupe/dropping)
(*) 1000/1001 frame rates are the alternative 23.976 and 59.94 Hz rates that are actually used for a large proportion of so-called 24p and 60Hz content. This is because the first US colour TV standard, NTSC, required a slight change to the field refresh rate to avoid the line/field-locked colour subcarrier potentially interfering with the sound carrier used for broadcast audio. We've been cursed with it ever since - even with HDTV (which has to be refresh rate compatible with SDTV for downconversion purposes)
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Wow, thanks so much for detailed info.
So, in layman's terms:
Adjust Display Refresh Rate - big changes in refresh rate, if TV supports it.
Sync Playback to Display - small fine-tuning to be better matched to what TV has switched to.
So for best experience, if my hardware can do it, I should use both.
This only leaves the question of Audio. I've read that "resampling" doesn't work with passthrough, so it's either "dupe/drop" or "adjust audio clock" for me. I am having constant issue with audio being out of sync with video on my platform (Minix X8-H). Which option would provide better "sync'ness"?
Thank you.
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correct, "sync playback to display" makes no sense with passthrough audio. in general a/v sync is better with passthough disabled. but not sure if it does matter in your case. sorry to say but Android audio driver is a nightmare.
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Nice! I'll try to find a good spot on the wiki to deposit this info.
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nickr
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Yes, preservation needed!
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Yes, it does. If you alter the video but pass through the audio to your receiver, they will be out of sync. That option only works right when all the signal processing is done together.
