[Mark_A_W]

JUDDER.

The hardware is perfectly capable of running a multiple of 23.976hz.

3:2 judder is unbearable to me.


Surely I can't be the only one trying to run a custom resolution with XBMC?

[davilla]

Interesting post about judder.

http://www.projectorcentral.com/judder_24p.htm

[ashlar]

Interesting post about judder.

http://www.projectorcentral.com/judder_24p.htm

I honestly find the article misinformative. Stating "Leaving conventional wisdom aside, if you have the option to play your Blu-ray movies in either 24p or 60p, don't be surprised if you prefer the relative stability of 60p." is unbelievable for me, IMHO. Being in PAL land I could *never* consider 3:2 judder "preferable" in any way.

Maybe if you are used to it after years and years of being forced to accept it. But I still find this tough to digest.

It is an interesting post, anyway, I concur.

[davilla]

What I found interesting was that some 24fps content has native "judder". I'll quote the section of the article;

If you've still got your Casino Royale disc in the Blu-ray player, you can see a good example of this. Go to chapter 9 again, and to 1 hour, 9 min, 6 seconds. Here Bond is walking through the hotel. Notice that the cinematographer places Bond in the right half of the frame, and the camera retreats as Bond approaches to keep him in a stationary position while the background pans. Bond turns to his right, and the cinematographer continues to hold him in the right half of the frame. When this scene is played in 24p, Bond remains stable and in focus while the background judders like crazy. When you play it back in 60p, the juddering effect in the background is still there, but it is reduced--it is easier to live with.

What this means to me is some 24fps content might have "judder" effects even if play back at 24fps. Zero sum game, then. Even with fancy anti-judder frame interpolation, you're going to end up with something blurred. Think of this too. When the studio did the original video content transfer to blue-ray, they had the chance to "fix" this but choose to leave it alone. They have much better hardware/software available too. But for example, in the Bond scene above, judder exists. So you really have to ask, is the "judder" you see an artifact of the display process or is it a native artifact in the video content.

[Mark_A_W]

Well, I've had a fun weekend..

My TV would not sync to any res higher than 640x480 from the intel onboard graphics. Tried custom timings, tried sync polarities....nup.


I ended up buying a cheapo Nvidia 8500GT from ebay, and after 4 hours battling with the Nvidia driver's custom timing settings, I got 1080i at 60hz and then 1080i at 71.928hz running. (You have to set it to 540 lines in the Nvidia settings, not 1080 like all other custom timing programs I've played with.)


And yes, XBMC sees my resolution as 72hz as you can set the GDI timing in the Nvidia settings.


PHEW!!!

[Mark_A_W]

The only way around this is to measure the refreshrate, but that's a bit error prone.

I've been playing with the syncing options for a while now.

I get the best results with them turned off.

- Using Audio sync I get tearing.

- I haven't used drop/dupe audio as I'm using analogue out and this option has just gotta be for SPDIF encoded DTS/DD packets.

- Using resample audio it's not smooth. And I can hear the audio pitch changing. It "warbles".

My refresh rate is set to 71.928hz. But XBMC detects this as 72hz, the GDI refresh rate. I think this mismatch causes issues.

There really is no way round measuring the refresh rate. Reclock, MPC-HC EVR Custom Renderer, and madVR all measure the refresh rate.

You can see this process as reclock is fired up for the first time - the reclock icon blinks red/green while doing the measurement. Once it's locked on it stays green. It only needs to do this once, not everytime it's used.

Back on XBMC I may get better results running a custom refresh rate of 72.000hz to match the GDI refresh rate. But that's not right. The source FPS is 23.976. The refresh rate should be an exact multiple of the source.

Anyway, I hope this feedback is useful.

Mark

[bobo1on1]

The mismatch in refreshrate doesn't matter.
Do you have triple buffering enabled by any chance? You shouldn't get any tearing at all unless you disable vsync.

[Mark_A_W]

Triple buffering?

In the video driver control panel?

I will check.


Re your tearing comment...umm..

I've found the exact opposite.

The PC is an E5200 dual core, in a dedicated system for XBMC running XP SP3. XBMC is basically the only application on the PC.

So far I've tried:

- Intel onboard video. Bad tearing if started with -fs, but ok without the fullscreen switch (known issue as I found reference to it here). My TV won't sync to it however...grr.

- ATi HD2600XT, borrowed from another PC. I did see some tearing, which it never does on the other PC. I didn't investigate due to the Powerstrip refresh rate issue.

- Nvidia 8500GT. Works with TV, Nvidia custom refresh rate is detected correctly by XBMC. But it tears at the slightest provocation. It's not powerful by today's standards, but it should be enough. I've fiddled around and got it working ok - by choosing the v-sync settings and fullscreen mode carefully (can't remember offhand which settings work). But one thing that absolutely causes tearing is Audio Sync.

Thanks

Mark