Can't get perfect 23,976Hz playback from my nvidia 8600GTS or my ATI 3870 either.
Maybe this can be related:http://forums.entechtaiwan.net/viewt...?p=22625#22625
Also discussed this with another guy in another forum. My concusion after alot of testing:
nvidia 8600gts vs ATI 3870.
The nvidia card have the following refresh rates to choose between in the control panel (latest forceware on vista 32 sp1):
24 gives 24Hz and 23 gives something around 23,976Hz but not exactly 23,976Hz. As PowerStrip can't be used with the 8000 series I can't really know the exact refresh rate.
I really can't tell exactly how long it is between each stutter. But somewhere between 2 and 3 minutes. The stutters are so tiny I can spot like 2 or 3 during a whole movie.
Th ATI card have just the option 24 in the Catalyst Control Center. And as I can use Powertrip with this card I can see that this option gives 24Hz output.
After some playback tests in Media Player I can see stutters every 42 seconds like a clockwork. And the stutters are very easy to spot.
Now I tested to creat some custom timings with PowerStrip. First I tried out 23,976Hz. I can't see a single stutter with this one. BUT I get tearing in fast moving scenes. So I tried tweaking it in steps of .001 Hz.
23,982Hz gives perfect playback without tearing. But I get stutters about every 3 minutes (same as nvidia)
I looked through all presets in PowerStrip and there is only one for 1080p at ~24Hz called 1080p 24Hz EIA/CEA-816B.
This preset used the exact settings I used to get 23,982Hz
Also gone through this:http://www.quantumdata.com/support/k...dardTiming.pdf
But it seems like the EIA/CEA-816B standard for 23,976Hz (actually called 23p in this material and also in other material I read through) is exactly 23,976Hz. Don't know why 23,982Hz is used in PowerStrips EIA/CEA-816B preset.
I have no idea why I get tearing when using exactly 23,976Hz. And I have no idea on how to get perfect 23p (as I learned it should be called) playback from my computer...
I have a small idea though. It might be related to a registry value called timestamp and is written by the drivers controlpanel every time you switch refresh rate. When using PowerStrip this value is not updated.
So if I switch from like 50Hz to 23,976Hz using PowerStrip I get jerky playback. But If I use the ATI control panel first to go from 50Hz to 24Hz and then fine tune with PowerStrip. I get 23,976Hz and its not jerky. But the tearing is still there.
I think the timestamp value is read by the renderer (EVR) and as PowerStrip does not write a new timestamp the renderer uses this timestamp value set by ATI CCC. So now we have a perfectly matched refresh rate. But the renderer does not match this refresh rate.www.earselect.se/pstrip.txtwww.earselect.se/ati.txt
There you can see the diffrence if you are interested...
Also did a fresh install of Vista 32 Ultimate SP1 for a second test with the ATI card. If something was left from the nvida driver that screwed up the result.
But no change...
Sorry for my bad english!
And yes I tweaked the registry for the ATI card and tried Vsync to eliminate the tearing (no luck).
This is driving me insane!