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-   -   HD Stuttering on 720p HDTV but not 1080P Monitor (http://www.nvnews.net/vbulletin/showthread.php?t=96351)

Jon 08-10-07 06:50 AM

HD Stuttering on 720p HDTV but not 1080P Monitor
 
I have my PC connected to a Dell 24" monitor and an LG 32" HDTV. The Dell can do 1080p and when I play HD content using powerdvd it runs really smooth. However, watching it on the LG TV (720p) it appears to have micro stutters which are really annoying.

Any ideas why this could be?

hordaktheman 08-10-07 11:31 AM

Re: HD Stuttering on 720p HDTV but not 1080P Monitor
 
It could depend on any number of things. What kind of media is this (Matroska, WMV, h.264) and how do you connect the computer to each respective display? Are you, for example, using DVI for the monitor and component for the TV? Are you using a PAL television at 50hz and the monitor at 60hz?

You might want to try making sure your TV is running at 60hz, or even unplugging the Dell and using your TV as a single display. My first thought was that the two displays are running at different timings, but it could also be that your TV (being a secondary display) isn't getting enough processing resources allocated to it.

Also, try shutting off any video acceleration on the graphics card and have your CPU process the video. If the video stream is native 1080p resolution, it could be that either PowerDVD or your graphics card is having issues downscaling it.

Jon 08-10-07 04:20 PM

Re: HD Stuttering on 720p HDTV but not 1080P Monitor
 
Quote:

Originally Posted by hordaktheman
It could depend on any number of things. What kind of media is this (Matroska, WMV, h.264) and how do you connect the computer to each respective display? Are you, for example, using DVI for the monitor and component for the TV? Are you using a PAL television at 50hz and the monitor at 60hz?

You might want to try making sure your TV is running at 60hz, or even unplugging the Dell and using your TV as a single display. My first thought was that the two displays are running at different timings, but it could also be that your TV (being a secondary display) isn't getting enough processing resources allocated to it.

Also, try shutting off any video acceleration on the graphics card and have your CPU process the video. If the video stream is native 1080p resolution, it could be that either PowerDVD or your graphics card is having issues downscaling it.

Hmmmm, now I'm even more confused... I just tried with/without hardware acceleration and there is no difference in cpu%. 6-13% cpu usage with or without hardware acceleration... surely somethings wrong there?

To be more clear, I am playing HD content from an xbox 360 HD-DVD drive. So I believe its VC-1. Both the monitor and the tv are connected using dvi cables (1m dvi for the monitor, 5m dvi for the tv if it helps). Also, both are 60hz according to nvidia control panel. I believe the tv is pal.

hordaktheman 08-11-07 10:01 AM

Re: HD Stuttering on 720p HDTV but not 1080P Monitor
 
Did you try setting the TV as a primary monitor? Or even use it as a single monitor by unplugging the Dell? I know hardware acceleration sometimes goes a bit wonky on a secondary monitor. The same goes with hardware overlays, where if you start playback on the primary monitor and move the window over to the secondary, there could be some slight synchronization issues. For example, your Dell could be using a 60.25hz timing while your TV uses a 59.75hz timing; both would be reported at 60hz while still not being in sync.

As for the hardware acceleration, that is a bit odd; I tried turning hardware acceleration on and off in PowerDVD and CPU usage went from 25-30% to 50-55%. I'm admittedly using a C2D at 2.66ghz (same gfx card), so it's not quite comparable. Does PowerDVD use all 4 cores on your system? If so, your CPU usage may be normal, but if it only uses 2 cores it's a bit on the low side, especially with hardware acceleration off. Then again, it may all be moot and irrelevant to the issue.

You can check if it's using hardware assist by setting the CLEV setting in PowerDVD (which is only available with acceleration off) to split screen. If you see a split image, hardware assist is off.

A third thing I'd like to ask is what resolution is your TV set at, and what is it's native resolution? TVs tend to treat signals a bit differently depending on resolution, and if it's (say) a 1360x768 panel and you're feeding it a 720p signal then it may be treating as a television broadcast or DVD player and using overscan and all sorts of post-processing 'enhancements' which may be further affecting playback. I assume you can pick some other resolutions on your TV than you've been using (say, 1280x768 or even 800x600); you might want to try playback at those resolutions just to see if you still get the stutters. Ideally, you'd want your TV to treat the signal as a computer signal rather than a television/DVD player signal.


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