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Tweaking the DVI/HDMI monitor for smoother video playback., Rant about jerky video playback.
psycho
post Apr 12 2012, 19:27
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Hello felow IT enthusiasts...

Something's been bothering me for quite some time now and I want to share it and I also hope someone might have some suggestions I haven't heard of before that could help me...

OK, as you might know, the video on a PC plays smoother if the refresh rate is set to a multiple of the video framerate. Say you have a video at 24 fps, it will playback smoothest at 72 Hz, 120 Hz. If you have a video at 25 fps it will playback smoothest at 75 Hz, 100 Hz. And if you have a video at 30 fps it will playback best at 60 Hz, 120 Hz.

I know all that and I live in a PAL area so most of my videos are at 25 fps and 24 fps. That means it is best for me if I set my Display Properties to either 75 or 72 Hz. MPC-HC player can switch these modes for me - you can define which fps go with which Hz. That's cool and I use that option.


Now we come to my problem. All of the above works if I connect my monitor via D-sub (VGA). It doesn't work with DVI and I haven't tried HDMI yet, as my manual says it's only for connecting to standalone players and not for computers (it explicitly says "HDMI not for connecting to a computer")... And I don't have the expensive HDMI cable anyway. So with DVI, my refreshrate is always 60 Hz on my monitor, no matter what I set on the PC. So the jerky video playback is always present as I almost never have 30 FPS video and for 25 and 24 FPS 60 Hz just isn't OK.

I can't help but wonder why on earth does DVI use the archaic mode of refreshing the screen?? As far as I know, LCDs don't refresh the screen as the CRTs do and DVI is meant for LCDs. So the logic suggests that there should be a mode of operation for LCDs to operate at "whatever-the-input-Hz" so to speak. I mean, it would rock to have such a mode of operation for DVI that it would actually send only changes of current display at any rate it happens... say with 24 FPS video, the DVI would refresh 24 times per second and that's it... Is there something like that? Can one achieve something similar with a PC and LCD monitor? Maybe HDMI (I have no experience with HDMI whatsoever so far)?


Well, that's it... I wish you all a smooth video playback and I hope someone can help me with some tricks. smile.gif


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psycho
post Apr 13 2012, 18:47
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Thanks for that review link (dankeschön! smile.gif). I'll read it whole later on.

I can also set only 59 Hz, 60 Hz and even 70 Hz when connected with DVI, but with D-sub I can select from 56 Hz to 75 Hz as it should be according to specs... so the specs clearly describe D-sub values. However, as I said, with DVI it doesn't matter what I select on the PC, the monitor is always at 60 Hz if I check it's menu... And that is what causes my problems.

Well, I will leave it connected via D-sub for now...


I will also try to somehow achive that some IPTV player will send interlaced picture to the monitor with the information that the picture need deinterlacing... I'm not sure how I will do this yet, but you gave me something to play with. smile.gif

EVR Sync on XP IS possible, but you must install NET Framework 3.5 Service Pack 1 (Full Package).

And I have also played with CTRL+J in MPC-HC and there I can see confirmation of the judder. No matter if I set overlay, VMR9, EVR Sync, the refresh rate matters and if it's a multiple of fps it's smooth and if not it isn't. How do I see that with CTRL+J? Well, when the refresh rate is a multiple of fps, the graph you see with CTRL+J is almost a perfect flat line, if however I look at the graph with say 60 Hz and a 25 fps video, the graph is a lot of triangles - jitter(?).


Thankyou for any input guys. smile.gif


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