IPB

Welcome Guest ( Log In | Register )

Tweaking the DVI/HDMI monitor for smoother video playback., Rant about jerky video playback.
psycho
post Apr 12 2012, 19:27
Post #1





Group: Members
Posts: 241
Joined: 14-October 05
Member No.: 25099



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


--------------------
lame -V 0
Go to the top of the page
+Quote Post
 
Start new topic
Replies
psycho
post Jun 25 2012, 18:14
Post #2





Group: Members
Posts: 241
Joined: 14-October 05
Member No.: 25099



All this time later and I have come up with the solution to my problem and I would like to share it so anyone with similar problem can maybe benefit from this...

So, the culprit was in AMD(ATI) "Catalyst Control Center". First, I had to uncheck "Enable GPU scaling" under "Digital Panel (DVI)", then I had to check under "HDTV Support", "Add 720p50 format to the Display Manager (PAL)" and I also checked "Add 1080p50 format to the Display Manager (PAL)" for full HD resolution to be able to refresh at 50 Hz. After all that I could use the "Force" button under "Displays Manager", "Displays Properties" to set it to either "HDTV Mode" 1280 x 720 @ 50 Hz or 1920 x 1080 @ 50 Hz.

Now I get super smooth 25 fps video playback!

So the "Enable GPU scaling" was forcing my monitor to always operate at 1920×1080@60Hz no matter what I have set. Strange, I can understand the resolution part of this logic but not the refresh rate part of it... Well, nevermind - solved! And just in time to watch UEFA 2012 championship via IPTV on the PC! smile.gif

(to be fair though, on this monitor I just can't see the difference in picture quality between D-sub and DVI... on my old monitor D-sub had some nasty noise, especially if displaying grey color... well, that's not the case with this one and all this quest for setting appropriate refresh rate via DVI was almost not necessary... almost, because 50 Hz was never before available to me and is even smoother than 75 Hz - guess it's because 50 is an even multiple of 25 and 75 is an odd multiple of 25...)


--------------------
lame -V 0
Go to the top of the page
+Quote Post

Posts in this topic


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 21st April 2014 - 09:22