Ubuntu + NVIDIA + Twinview == video tearing

[BicyclerBoy]

Spending too much time on the internet is a good way to find out mostly useless information.

The 9600GT video performance was as good as it was in 2008..
The 8400GS & some nVidia IGP were almost as good.
The 9400GT was the best lower power HTPC card but the 9500GT was fast enough to post-process.

(Wikipedia)
The GT2xx family (end 2009) (not GTX2xx) introduced the better VPU.
GT430 Oct 2010
The GT520 (April 2011) has introduced the best VPU to date but...

The modern video card has (2) main functional blocks: openGL core & video bitstream decoder VPU.
The VPU performance is the feature set or PureVideo designation.
The openGL performance is linked to mem bandwidth & clock speed etc.
Old gaming video cards were all openGL performance only.
The GTX580 video decode is likely the same as GT520.

The openGL processor core shaders are used for post decode processing: de-interlacing, scaling, denoise, sharpen & colour-space conversion.

So from a datasheet you could try to compare shader clock & core configuration, not sure if this would help. You would need to be GPU designer to be able to compare the different architectures of AMD, nVidia & Intel.

[Roasted]

Considering the GT520's price is actually very affordable, I might go for that instead of the GT430.

The problem I have now is what other gear to buy. I suppose a low powered dual core proc and mid-range board should do the trick...

[BicyclerBoy]

Don't buy a GT520..
There will certainly be new cards out next months..
So far only GT520 NVS 4200 have VP5/ feature set D..but both of these are non-starters.

VDPAU decode & CPU de-interlace is not feasible due to massive bus traffic except maybe in optimus graphics setup. You need so fast a PC you may as well use the CPU only..

I would guess that a new GT530 would be VP5 (4Kx2K or 3d 60Hz HD) so perfect & future proofed.

[Roasted]

Don't buy a GT520..
There will certainly be new cards out next months..
So far only GT520 NVS 4200 have VP5/ feature set D..but both of these are non-starters.

How does that help me.. now?

I'm likely buying a GT 430 now that I look more into it. The 520 looks to be rock solid for a HTPC setup but the 430 seems to be far more common with what users are talking about. Now I just need to figure out... do I go with a more budget build and get an AM3 combo or should I get a quieter and more power friendly Sandy Bridge? Either way, despite the SB having IGP, I'd much rather have a dedicated GPU such as the 430.

[BicyclerBoy]

It helps by making it harder to make a decision..

I would get the intel CPU & see if the GPU works okay, & have a PCIe x16 slot free.

Check out the B model (GT430).
http://www.anandtech.com/show/4374/c...x-motherboards

[Roasted]

I saw that, but @ 220 bucks it's FAR more expensive than getting the board and GPU separately.

[BicyclerBoy]

Yes, Zotac + ITX + iCPU = expensive.

But at least these non-atom ITX solutions with real GPU have started to come out..

[Roasted]

I ended up finding a 50 dollar visa gift card, which pushed my decision that much easier. I ended up getting the i3 2100 3.1ghz, an MSI H61 board, 4gb DDR3 1333, and a GT 440 1gb GDDR5 card.

I think this is overkill for a standard HTPC, but it was hard to justify getting gear that I haven't experienced with a real HTPC setup before. But considering I may rip my collection I decided a little more horsepower couldn't hurt to be safe.

I also re-tested the video tear thing last night with my dual monitor desktop setup and it's definitely true. A single monitor is great. My duals... tearing.

Anyway, appreciate the help you offered through this. I hope somebody else can learn what I learned.

[BicyclerBoy]

To clarify/summarize previous posts.

single screen tearing (VDPAU) caused by compiz/composite redirection
- solve by un-redirect full screen

opengGL tearing
- triple buffering maybe fix
- set refresh rate in composite (twinview) else auto detect.
- set vsync
- composite settings

twinview tearing caused by incorrect refresh rate reporting
- solve by manually setting refresh in composite & above.
- not a flexible fix.

Workable:
-composite workaround settings

Best soln:
non compositing desktop manager
purge compiz
separate X screens, no twinview.
10.04 10.10 work

There is no tearing with openGL or VDPAU if you use Ubuntu 10.04 & separate X screens. This should also apply to Xunbuntu/mythbuntu/Xfce desktop no compiz.


The VDPAU benchmark qvdpautest does not seem to be affected by composite settings maybe because it does not run full screen or it benchmarks reusing a small number of frames.