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Digital vs. HD Quality via Cable

post #1 of 8
2/15/09 at 6:58pm
Thread Starter 
OK, educate me guys-

I have an HP z557 with mostly stock configuration (including ATI Wonder and Hauppauge PVR-500 dual NTSC cards) -- I have only upgraded the video card to an Nvidia 7600GT and am running XP-MCE 2005. The quality of recorded TV (live or playback) fed from my Comcast cable connection through the z557 was always less than what I'd hoped for, but until recently I suspected that was the fault of a poor quality TV. I have recently upgraded the TV to a Samsung 4234 Plasma and have the z557 connected to it using a DVI/HDMI cable. I can now compare (with the TV's PIP feature) the same cable signal rendered through the internal Samsung tuner and also the through the z557. The quality difference when viewing a DTV/HD channel is obvious!

I am set to record "Best" quality in MCE. Since my ATI Wonder is HD capable, my 7600GT is HD capable and everything else is the pretty much the same (cable input and TV display/output) - I am at loss to explain why the TV seems to be giving me such better quality than the z557.

Is this normal? How do I improve it?

Thanks
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post #2 of 8
2/15/09 at 8:06pm
You can't record HD or digital cable using XP-MCE, only Vista with the TV Pack or Windows 7 can work with a tuner card that has a QAM tuner installed which is the type of tuner required to received unencrypted digital/HD broadcasts from your cable company. There are some other media center type programs that will work with QAM tuners also.

In short with your current configuration you have no way of recording HD from cable, there's no way to make it look as good as the QAM tuner built into your TV.

For more info on options to use QAM, try the Home Theater PC section.
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post #3 of 8
2/16/09 at 12:45am
The reason for the diff in PQ is that you're comparing a clean (sometimes HD) digital signal on the TV vs an analog signal via the HP PC (it is not the same signal when you are comparing them in PIP).

As was mentioned above, to get the same signal you'd need an upgrade of both the tuner and the OS on the PC if you want to use MCE. You could keep the OS and get just a QAM tuner which will probably come with some QAM recoding app of its own.
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post #4 of 8
2/16/09 at 7:32am
The analog channel (2-67) are being encoded using a low cost encoder chip on your tuner card for use with MC and are being decoded by PC graphics card for output. The TV's own analog tuner just displays the normal analog signal
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post #5 of 8
2/16/09 at 11:17pm
Thread Starter 
Thanks, all. Obviously, I have a bit more to learn here. I assumed that because both tuner card and video card were HDTV capable they they should be able to handle digital signals as well as the TV. It sounds like that applies to OTA, but not the QAM signal that comes over a cable channel, correct?

One last question -- if I get a new QAM-capable tuner card, is it worth upgrading to Windows 7 MCE, or is something like BeyondTV (with inherent support for QAM) on my existing XP box a better option?

Appreciate your advice!
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post #6 of 8
2/17/09 at 4:27am
If you do decide to add new hardware, consider the SiliconDust HDHomeRun. It can remap the QAM channels to trick MCE and VMC into working with them just like they were ATSC, and it also supports all the other PVR packages out there so you can use whatever software you like best.
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post #7 of 8
2/17/09 at 7:29am
MC-N....,
With either the HDHR or a QAM capable tuner card you will only receive the Unencrypted QAM channels from your cable company. These channels are normally only a subset of the local OTA digital channels that you can receive with an antenna since the cable companies are not required to provide more then one digital sub-channel from any local broadcaster
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post #8 of 8
2/17/09 at 7:43am
Quote:
Originally Posted by coyoteaz View Post

If you do decide to add new hardware, consider the SiliconDust HDHomeRun. It can remap the QAM channels to trick MCE and VMC into working with them just like they were ATSC, and it also supports all the other PVR packages out there so you can use whatever software you like best.

This would be your most pain free option. Make sure you have plenty of disk space also, HD recordings take up more space then their SD counterparts.
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