WMC jittery playback

[PLBarton]

have a dedicated Mac Mini i7 quad-core (2.3GHz), 16 GB RAM, 2 x 1 TB (5400 - rpm) hard drives and built-in Intel HD Graphics 4000. I run Windows 7 natively on the box without bootcamp (I have installed all the bootcamp drivers so that everything is recognized in Windows). My tuner card is a single HDHomeRun Prime with a cable card from Charter Cable. I have 2 Xbox 360 extenders networked together over a DECA Modem network. The Mac Mini is connected directly to my main TV while the 360s are connected to other TVs throughout the house.

Here is my problem, when I watch TV on the main TV through the Mac Mini there are some channels that come through very jittery. While other channels are perfect. Examples of each are Velocity Channel is choppy and it seems like the Mac MIni has to get to a point in buffering before it stabilizes. Even when the output stabilizes when the channel broadcast switches to a commercial the jittery playback will occur again. To contracts that all network channels (FOX, NBC, CBS, ...) work perfectly all the time.

Here is the weird part, those same channels (Velocity Channel) that are jittery on the Mac Mini, playback perfectly on my Xbox 360 extenders.

Does anyone have any experience with this sort of issue?

If you have any questions or request for information let me know and I will do my best to fill in the blanks. Any help is appreciated.

Thanks,

Peter

[Crash2009]

Could you diagram your system for us. Also we need model numbers for the DECA devices, and any splitters, amps, etc.

Also please show any Ethernet switches, routers and the model # of your HTPC's NIC.

Am I reading you right? Are you running Charter Cable through a system designed for Direct TV?

[richard1980]

Based on the fact that playback is perfect on the extenders (which route everything through the host computer), I'm inclined to believe this is an issue with the graphics system on the computer. Is there any way you can capture a video of the issue?

[PLBarton]

I do not want to disregard Crash2009's questions, but I believe ricahrad1980 is hitting the nail on the head. The Mac MIni model I am using has an Intel Graphics 4000 video card built-in with an HDMI output directly on the back. In doing more research I did read a recommendation to disable "dynamic contrast" in the Intel Graphics control panel. I have done that this evening and the results are not exactly perfect. I get limited jitter on the same channels I did before, but they appear to clear up after 10 or so seconds. I can live with this, I just have to ensure this is the case for a longer sampling period. If anyone has more information on the dynamic contrast I would love to hear it.

Crash2009, in response to your comment about charter cable through a system designed for DirecTV. I use the DECA modems, which are a remnant of my DirtecTV installation, because my only alternative is a wireless network. I do not have Ethernet throughout my house. The shared 200Mbps provided by the DECA modems is more than enough for the two extenders I have on it.

[Crash2009]

That's OK.

[cKuR6]

OP, since your extenders play perfectly, I'm on the vid card bandwagon for this issue.

How do you have the hdhr connected to the HTPC? Is it over MoCA?

[PLBarton]

To clarify that point. My Charter Cable signal comes in directly to my computer room and has a single splitter passing the signal between my cable modem and the HDHR Prime. The HDHR Prime is connected to a Gigabit D-Link switch which my Mac Mini is plugged into as well.

[cKuR6]

Perfect, then MoCA is not your concern.

[Crash2009]

While we are waiting for your video capture, and Richards diagnosis, how are the MoCa devices connected to the Ethernet Network?

[richard1980]

There's not really anything I can offer without seeing what the OP is seeing. I suspect this is yet another 29/59 related problem.

[Crash2009]

To me it's hard to understand how the extender plays it correctly, And the htpc can't get it right. Doesn't that suggest a htpc display problem?

[richard1980]

Yes. The extender is getting a signal through all the same cable and network connections, and the data is still going through the computer's NIC and storage system, so about the only thing left is the graphics system.

[Crash2009]

These Intel guys sure are serious about seeing exactly what's going on with the Graphics System. I never realized these Ivys were so customizable. I have one over here but I never really looked into it because there were no problems, well except for bypassing display port in favor of HDMI.

Richard, have you used any of these Graphics Performance Analyzers? Looks like a 6 month project just to read the manuals.

[PLBarton]

Thank you all for your comments, it does appear that I am suffering from the 59/29 problem mentioned throughout post on this board. I was lucky enough to have a third Xbox 360 already attached to my main TV so I am now running exclusively over Xbox 360 extenders. Also, now that you do not need a Xbox gold membership to download apps I have installed PLEX on all the Xboxes. Except for the long boot up time for this seems to work really well.

Thanks again everyone.

Peter

[richard1980]

Richard, have you used any of these Graphics Performance Analyzers? Looks like a 6 month project just to read the manuals.

I haven't had a reason to...but it does look like something I would be interested in given the spare time.