Jerky picture after upgrade to Samsung 40" (2 Viewers)

[SweMart]

Hi,

I replaced my old 32" Philips CRT with a new Samsung LE40R51 LCD this week.

After the monitor switch I also upgraded the drivers for my Asus Nvidia 6600 Silencer card. When watching sports like football or icehockey the picture becomes quite jerky, the old TV did not expierence this.

I'm connecting to the TV using a VGA cable, have also tried DVI->HDMI with the same result.


I use the Nvidia PureVideo codecs but I have also tried Intervideo, PowerDVD, Descaler and MPV with the same result. I have also enable/force Vsync on in the Nvidia application. I'm running MP in exclusive DX mode.

What else can I try? Any recommendations on PureVideo codec, driver settings, i.e de-interlacing methods etc etc.

I'm using the latest RC4 SVN, screen resoultion is 1360x768 @ 60Hz which is automaticly picked up by the Nvidia driver and all of the timing settings are according to the Samsung manual.

The FIFA World Cup is approaching fast so I really need to iron this out asap

 

[ctgoodman]

I've heard that about other LCD's as well. From some things I've read LCD's may experience issues with seeming choppy during programing that has alot of action or fast camera panning as in action movies and sports. Do a google for some similar topics including LCD, Ghosting, Streaking you'll find some out there. Do any of these describe the issue you are experiencing. Is there anything in your specs that list the response time? Seems like when you start getting above that 20ms is where you start start seeing the ghosting and streaking.

 

[ziphnor]

You should be more specific as to what kind of jerkiness it is, does the image tear, freeze or is it just that panning is jerky? Ghosting and streaking are different issues entirely.


I would watch out for the following:

1. 50Hz -> 60Hz conversion
If you run the display at 60Hz but the TV signal is PAL (720x576i at 50hz) you might experience some jerkyness.

Try hitting Shift+! on the keyboard it will display information regarding framerates, dropped frames etc.

2. Higher resolution
You new TV has a much higher resolution than the old CRT TV and is progressive. The computer has to upscale the video signal to the higher resolution as well as perform de-interlacing, which can be demanding. Check that the CPU load doesnt spike at any time while watching.

3. New Driver
Have you tried reverting to the old driver? Its always a bad idea to change more than one setting/device at a time on a HTPC

On a side note:
I would recommend using DVI->HDMI, my HDTV at least black tones were rendered incorrectly using VGA, and the HDMI input was much better.

 

[SweMart]

You should be more specific as to what kind of jerkiness it is, does the image tear, freeze or is it just that panning is jerky? Ghosting and streaking are different issues entirely.

My problem is panning.

1. 50Hz -> 60Hz conversion
If you run the display at 60Hz but the TV signal is PAL (720x576i at 50hz) you might experience some jerkyness.

VMR9 show 50 when doing "shift+!", all of the other figures are zero(drop, jitter, fps etc etc).

50Hz is the theory I'm working on right now, the standard Nvidia drivers only lets me set 60, 70 and 75. I guess I could solve it by using Powerstrip but I haven't used it before and I currently have no idea how to populate all of the settings.

CPU load is something like 35%, nothing to worry about... right?

I'll try to revert to the old Nvidia driver as well.

Do you know of any good Powerstrip howto that actually covers PAL? The ones I've found are really focused on NTSC.

Cheers,
Martin

 

[tourettes]

VMR9 show 50 when doing "shift+!", all of the other figures are zero(drop, jitter, fps etc etc).

I think it's only showing that what MP is outputting, but the video card is still using 60Hz and that will cause the jerky playback as there is no way 25fps material can be presented in 60Hz display. It's like you would be sharing 100 candys between 60 people, it's just not possible to get an even share for everyone

NVidia's drivers have option to create custom resolutions, use that option to make 50Hz display mode.

 

[surfermc]

I think it more to do with the refresh rate of the screen than the output of Medaiportal. Have you tried any other input sources?

 

[ziphnor]

I think it's only showing that what MP is outputting, but the video card is still using 60Hz.

Im not sure whether its the video card or MP which is doing the 50->60 conversion, but i have noticed that if i run a 50Hz movie at 60Hz on my HDTV MP will report a high jitter number, while running at 50Hz will reduce the jitter to zero if i remember correctly.

 

[ziphnor]

Do you know of any good Powerstrip howto that actually covers PAL? The ones I've found are really focused on NTSC.

Dont worry about PAL vs NTSC, just focus on changing the desktop res. to 50Hz. My HTPC uses ATI, but im betting that the nvidia drivers will allow you to set 50Hz if you look closely. You probably also want to set the frequency override, because otherwise MP might decide to switch to 60Hz again. I would try to download the Moninfo util from the Powerstrip homepage, it will list the timings the tv claims to accept, but dont be surprised if this information turns out to be bocus.

There is of course also the possibility that the LCD display doesnt really support 50Hz, ie it will convert anything 50Hz to 60Hz itself. In that case you should still try to set the HTPC output to 50Hz as the TV might be better at performing this 50->60 conversion.

 

[SweMart]

Dont worry about PAL vs NTSC, just focus on changing the desktop res. to 50Hz. My HTPC uses ATI, but im betting that the nvidia drivers will allow you to set 50Hz if you look closely.

I'll try to fiddle around with the refresh rate settings as soon wifey & co will leave the tv alone

Another question, someone at a swedish HTPC forum recommended me to use a multiple of 25 because of PAL. I set 75Hz but that just made the jerkiness even worse, I know for a fact that it was 75Hz since I have a "info" button on the LCD remote that show current resoultion+refresh.

Cheers,
Martin

 

[ziphnor]

Another question, someone at a swedish HTPC forum recommended me to use a multiple of 25 because of PAL. I set 75Hz but that just made the jerkiness even worse, I know for a fact that it was 75Hz since I have a "info" button on the LCD remote that show current resoultion+refresh.

As i said previously its hard to tell whether or not that information can be trusted, it might just be showing 75Hz as *input*, while it converts to 60Hz internally. PAL is completely smooth only at multiples of 50Hz.

However PAL consists of 50 interlaced half-images which can be de-interlaced to 25 progressive frames which can theoreticly play smoothly at 75Hz, but i would be surprised to see it working practice, since the 25 frames will be duplicated for a 50Hz progressive output and then the 50->75 conversion will take place.

Forcing 50Hz is the best way overall, i havent had jerkyiness problems on my HDTV after i forced 50Hz(as mentioned above, its a good idea to use the frequency override in the drivers to prevent programs from suddenly switching to 60hz).

EDIT:
If you have a standard SCART-output DVD player you could try playing back a DVD through that, it will output 50Hz interlaced, and the TV will deal with it as best it can, if its still jerky, then the LCD is simply incapable of doing 50Hz!