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Poor picture quality for Cable TV

post #1 of 21
Thread Starter 

I've been VERY happy with my current gaming HTPC build. Everything is working well and humming along and I'm thrilled.

The one downside, though, as compared to my old cable box provided by TWC is the picture quality. It simply isn't as good now through the HTPC with the cable being brought in through the HDHomeRun Prime and cable card and watched through WMC.

At first it was REALLY bad, but I found that I had to change the levels to 0-255 and that made the image look better (before there was no contrast and everything was washed out).

What I'm seeing badly now is a lot of artifacts-I would say it is like macroblocking or compression artifacts. They are strongest in the shadows. It's pretty awful. Even my girlfriend, who can't tell the difference between BluRay and DVD, said something.

Any idea on how I could improve the image quality?

I'm recording with a HDHomerun Prime, Windows 7 Ultimate, via Cable Card tuner and Tuning adaptor from TWC. Playback is in WMC, obviously. Video card is Nvidia GTX 680, output via HDMI.

Thank you!
Edited by GrantMeThePower - 4/6/13 at 10:24pm
post #2 of 21
Are you on the latest firmware on the HDHR Prime? Do you have any "smart" switches or routers between the HDHR and the PC? What NIC is in the PC, if Intel include the model number.
post #3 of 21
Thread Starter 
I am not on the very latest firmware. The last one they came out with to allow DLNA service, was not one I upgraded to. Since I didn't need DLNA and since I wasn't having issues, I thought it was best to not upgrade to it. I am on the firmware before that.

I have a router between the HDHRP and the PC...isn't that a requirement? I thought the HDHRP had to go through your router. It is an apple airport extreme (newest version).

I am using the ethernet port on the motherboard. The motherboard is an Asrock Z77 Extreme 4. It appears this is a Broadcom BCM57781.
post #4 of 21
Does not have to go through a router. Can go through a switch.

NIC should be OK.

Anything like this?

post #5 of 21
Thread Starter 
No, no. Not nearly that bad. More like serious compression artifacts. Like of a shadow made out of only 3 gradients when it should be a smooth transition.

I feel like it is something in the playback, not the recording. That is because I haven't noticed the issue when watching on the extender, just through the htpc itself.
post #6 of 21
Are you set up in WMC as a Television or as a Flat Screen?

Edited by olyteddy - 4/5/13 at 10:03pm
post #7 of 21
Thread Starter 
I'm set up as a projector. My display is a Sony Projector.

I went back to the extender and watched a couple of scenes that were really bad and I did notice some of the macroblocking/compression artifacts...just not as bad. That may be because its the difference between a 42" flat screen vs a 100" projection screen.
post #8 of 21

Sounds to me like your cable provider is compressing the channels too much for your taste - check what all other channels are on the same frequency via the HDHR Config utility.  Not that knowing this will fix anything but it may give you some insight as to how many channels, how much content (between SD & HD per frequency) your provider is trying to push.  Maybe your contacting them at a high enough level may help them realize how degraded they've made YOUR service!


BTW, your thread started out focused on the Cable Box and never mentioned your issue is with the CableCard's tuning... I was lost when I first read it.  Seems you are NOT concerned about their box, but your Prime reception quality.  To that end, have you checked the signal strength of these channels?  Open your Prime device from your NETWORK and check the Status, then a particular tuner - it will tell you:




Signal Strength 100% (15.6 dBmV)
Signal Quality 100% (35.4 dB)
Symbol Quality



all of which could indicate a low quality cable line into your house or at the CableCard drop.

post #9 of 21
The reason I asked about your setting is because setting it to Television is the way to get one-to-one pixel mapping. Those other settings rescale the picture. That control should actually be called 'How much overscan would you like?'...wink.gif
post #10 of 21
Thread Starter 
Originally Posted by Andrew Hornfeck View Post

BTW, your thread started out focused on the Cable Box and never mentioned your issue is with the CableCard's tuning... I was lost when I first read it.  Seems you are NOT concerned about their box, but your Prime reception quality. 

I'm sorry. I reread what I had written and I can see how it was unclear. I've edited the original post to try to be more clear. I no longer have a cable box. I was saying that the image now is poor compared to the previous image I was used to with the old cable box that TWC gave me.

Thanks for catching that, and I apologize about the confusion.

I'll start checking the signal strength on the channels I notice the issue most. I think it was FXHD that I noticed it the most, but I'll double check.
post #11 of 21

I've also reread and feel pixelation is due to either poor signal quality (not compression which usually shows up in fast motion scenes which you didn't mention), or more specifically a non 1:1 pixel setting.  What is your display/TV, and are you driving it with the PC set to its native panel resolution???  You could be seeing 'smearing' due to the TVs internal scaler.  OK, ok... read more and you have a Sony PJ - which model?  I had a 10HT and AW15 before my Epson 8350 I have today -- again, you need, more absolutely MUST send a Sony it's native panel resolution from your PC and this can not be altered by your video application and/or AVR, or the Sony will kick in its scaler and you'll not like the image quality!


How's your desktop look?  Have you run the CableAdvisor for WMC?  Look at your Sony menu and read what it says is the resolution it's receiving when you're playing WMC and while you're simply at your desktop.

post #12 of 21
Thread Starter 
Thanks for your reply.

The desktop and games look great. Sharp. Smooth. Perfect. I believe I have 1:1 pixel mapping. The projector correctly shows 1080P60.

The projector, by the way, is the VPL-HW30ES.

I tried to check the cable strength and for whatever reason the HDHomeRun Prime software doesn't show me the signal strength for channels over 157. Very weird.

That being said I flipped through a lot of the channels between 2-157 and saw a wide range of stregth percentages. It seems like the average would be in the mid 70's.

Is that a low enough number to explain what I'm seeing? Is there a way to improve it? Wouldn't an amplifier add noise to the image?

Thank you!!
post #13 of 21
You can also check signal strength and quality from a browser by going to the address of your Prime. You'll find a menu that leads to this:

More important than signal strength are the two quality figures. Have you tried changing your display type to Television yet? It really cleared up the PQ on both of my HTPCs.
post #14 of 21

You're comparing the picture quality of the CC to your old STB - where do you have the Prime?  Specifically, did you add a splitter to create a cable connection to the Prime?  Where along your home's "distribution" does it tap in?  Is this closer or farther than where the STB was?  I'm trying to get you to assess how your cable strength/quality could be degraded from where the STB was installed.


That's one fine PJ -- I was on the fence when my AW15's bulb grew old and couldn't justify the $2,500 ~ 3,000 for the 30 and opted for the Epson.  At 1080P60 it's receiving full resolution which is what it needs, YES, this is 1:1.  Are you certain that never changes when you open WMC?  If not then I'd say signal strength is causing your mild pixelization and signal in the 70's supports that.  Try testing the Prime by hooking it up closer to the entrance point to your home, where the signal strength should be best, and YES, a small distribution amplifier ($20~25) would help, especially if your cable is being split into TV, internet Modem, Phone Modem as mine is!  They provided one for me when they saw I have a HDHomeRun Prime, their DVR cable box (free for a year, included), and 3 other NTSC tuners needing a feed (to capture their remaining analog stations) in support of my HTPC/whole house setup.  I'm telling you what MY house has, yours may not be the same, but the Prime has a signal meter as ted and I have explained, use it!  If you have an internet modem it will have a home page where you can read its signal - use it to establish a baseline on whet's (hopefully) entering your home - if it's too low or poor quality a visit from your cable provider is in order.  You need to get the entry point value and then the value at your equipment as arranged, then adding an amp to see your improvement.


One other point: how's your network usage?  The Prime is a NET device, are you saturating your LAN?  Surely you're not connected via Wi-Fi, I hope...

post #15 of 21
Thread Starter 
Thank you for all of the feedback.

The HDHomerun Prime is in the same place in the loop as the STB used to be. It was a straight swap. What I have is this:

Main line to the house links to a 3 way splitter outside. These three go to the living room, projection room and bedroom.

The projection room feed then has a 2 way splitter right before going to the cable modem and the HDHomerun Prime/Tuning Adaptor. The distance between that splitter and the tuning adaptor is only like three or four feet. It is right next to each other in a closet.

My question on checking the strength is this...how do you change the "virtual channel"? When I go to the hdhomerun prime through a browser it isn't tuned to anything, so it doesn't show a strength. I had to go to the other application to change the channel and see the strength, but that is where it wouldn't let me scan past 157.

I did change the type to television, but I did not find any difference, unfortunately. The projector does still report the correct resolution and frequency. It is just during playback that I notice this.

I've been paying much closer attention when watching on the extender in the bedroom, and it is definitely happening there too. I'm thinking it is more related to the recording quality than the playback settings.

Where in my chain would I add the amplifier? Is there not a concern about adding noise to the signal?

Thank you!
post #16 of 21

When you installed the s/w for Prime they gave you a folder in the programs list.  Inside there is an app called config, use it.  It allows you to pick which tuner -0, -1, -2 and to manually enter/scan and view what it has tuned.  WHILE that has a channel tuned it will show you the signal values as well as you can then go look at the Prime in your browser and see the pic ted showed. 


You say you had to go to another application to change the channel, what application are you referring to?  Actually, you can use WMC (in a window) to "tune" your channels and watch the Prime in a browser to read signal strengths as well as RF and subchannel numbers!  In fact, when you installed the Prime S/W you did a scan, that scan will allow the Prime application called QuickTV to tune a channel - again, now you can use the browser to view the signal strength.


I'd say if only the Prime has signal issues, place it just upstream of it and not the leg to your modem.  First, you need to gather all the signal strength values for your Prime and modem.  Once you have these you may get your cable company to assess the levels because they should be providing you a signal level that will not pixelate... put this on them before you buy new equipment - especially since the cable route is so straight forward.  Also, I don't have a TA which may be adding to your signal issue - what if it's faulty, itself?  Again, reason to contact them.


Recording quality is not an issue because the ATSC signal is mpeg-2 encoded and streams right onto your HDD.  If you have playback issues you should look at the h/w and codecs you're using... or, again, how's your LAN usage?  You mention an extender - don't they need lots o' RAM in the "server" to stream programs to an extender?  As I understand it, low RAM would create a bottleneck and quality would suffer on the extender... you are talking about a WMC extender, or is it a Roku or other device that needs .264 compression on the fly (CPU intensive) to send the stream?

post #17 of 21
Thread Starter 
I have 16 GB of RAM, and it is an Xbox 360 extender. My network usage is very low. There are not other people or computers using it.

I am retarded for not thinking of just tuning in WMC. lol. I'll try that next.

The Config application is the one I was using. That is where it wouldn't let me change the channel past 157. Quick TV doesn't work without a full channel scan. I ran the channel scan again until it got to somewhere in the mid 400's and it took forever so I canceled it, thinking that was enough...it wasn't. I didn't go back through the whole thing. I can set it to run tonight before I go to bed, i suppose.

I need to be able to split the signal to both the modem and the HDHomerun Prime, because otherwise I have no way of getting the cable to the modem. I could install an amplifier before the split or after the split.
post #18 of 21
Originally Posted by GrantMeThePower View Post

I have 16 GB of RAM, and it is an Xbox 360 extender.
Another thing to try is the network tuning wizard in WMC on the Xbox. That will confirm whether you network bandwidth is as good as you think it is. If you don't get 100% green bars, your picture will be bad, just as you've described.
post #19 of 21
Thread Starter 
Ok I checked the network tuning wizard on my xbox. All green.

I checked a few of the channels by tuning in WMC and then minimizing. I'm seening 80-95% on the signal strength, and 100% on the signal quality and symbol quality. I think on one channel I saw signal quality at like 96%.

Those numbers seem pretty good, don't they?
post #20 of 21
Those look pretty decent.

What you haven't mentioned is what CPU/GPU graphics you are using, and if you have up to date drivers and any codecs installed.
post #21 of 21
Thread Starter 
I have a Core i5 3570K and a GTX 680. My graphics drivers are up to date (the latest came out about two weeks ago or so). I do not have any codec packs installed beyond what is baked into WMC. I do not use the HTPC for any dvd, bluray, rips, iso's, etc. Only for cable. Since it is copy protected I can only use WMC.
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