Cable card box equal HD output? - AVS Forum
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Old 03-24-2013, 07:28 PM - Thread Starter
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I just got a cable receiver box from Comcast (coaxial cable/not sure if this matters)

I was gonna go by local Comcast and pick up a cable card and then buy a InfiniTV 4. Since I'll get the cable card and bypass the "digital" receiver box and plug it striaght into my PC does that mean I now can get 720p/1080p output?
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Old 03-24-2013, 07:54 PM
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your output will be whatever you set your PC's resolution to. if you have a 1080p tv it will be 1080p - your video card will upscale 720p to 1080p, and will deinterlace 1080i into 1080p.

on my bedroom tv it is actually 768p that my PC outputs.

this does not mean Comcast is going to send 1080p - they don't do any of that. But your computer will scale to match your display.

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Old 03-24-2013, 08:01 PM - Thread Starter
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So that is a yes? smile.gif Can't wait to buy one of these suckers!!! Love how fcc regulated these things
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Old 03-24-2013, 08:53 PM
 
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You will set the output of your video card to match the maximum resolution your TV can play. For most people (in the US), this will be 1080p 60Hz. It will no longer matter what the input resolution of your cable channel is, the video card will change it to be 1080p 60Hz and send it to your TV that way. If the channel is 720p, your video card will change it to 1080p and send it out. If your channel is 1080i 30Hz, the video card will change it to 1080p 60Hz and send it out. The higher the resolution of the original channel the better - but all the non-HD channels will be converted to 1080p and sent out that way.

The nice thing about this is you do not have to worry about any of the other components in the system needing to perform HDMI handshakes, etc., each time the resolution changes - since it will never change for you.
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Old 03-24-2013, 09:16 PM
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Precisely speaking, it's 59Hz. And if you care about pulldown judder in movies (telecined in broadcast movies), it's 23Hz.
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Old 03-25-2013, 06:47 AM
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^^ But the conversion from 23Hz to 59Hz is made elsewhere before the signal gets to you tuner card or HTPC, Right?

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Old 03-25-2013, 07:01 AM
 
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Precisely speaking, 23.976 does not round to 23 and 59.94 does not round to 59. wink.gif


What he is trying to say is that some video cards will give you the option of using 23 or 24 and 59 or 60. Given the choice, choose 23 and 59. The 23 and 59 are used as a shorthand method of describing the longer numbers I listed above, even though it is an imprecise way of denoting them. As a note, most people do not notice the judder in movies - but if you do it can be quite maddening I have heard.
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Old 03-25-2013, 07:08 AM
 
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Quote:
Originally Posted by Sammy2 View Post

^^ But the conversion to 59Hz is made elsewhere before the signal gets to you tuner card or HTPC, Right?

It is broadcast (or sent from disc) in one or the other, no conversion is done prior to your tuner card getting them. Most broadcast TV is done in the 59.94 format now, so that is what you will receive. If you set the vid card to 60, it will output 60 and does its frame magic to do so - if you set it to 59, it will get closer to the actual 59.94, though I have read that no video card actually does it perfectly. BluRays (and DVDs I believe) display in 23.976, so the same thing applies to them with the 24 and 23 settings in the video card, and (again, from what I have read) no video card can output the exact correct number.
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Old 03-25-2013, 07:33 AM
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Okay. I edited my comment probably about the same time you were responding thereto. What I meant is that for broadcast TV, the change from 23.xxx to 59.xxx is not made in any equipment I have but rather somewhere else along the delivery chain.

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Old 03-25-2013, 08:03 AM
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Movie is usually 23.976fps regardless of resolution, that is encoded in MPEG-2 (or AVC) at 29.97fps interlaced by 3:2 pulldown (= telecine), then broadcast by modulation. The tuner demodulates the signal and reproduces the MPEG-2 (or AVC) 29.97fps interlaced stream. The software player/hardware decodes MPEG-2, then produces a 23.976fps progressive video stream by *inverse telecine*. If the refresh rate is 59.94Hz, then the graphics card repeats frames in 3:2 pattern (another 3:2 pulldown) and you may see pulldown judder. If the refresh rate is 23.976Hz, you won't see judder unless your display does not support 23.976Hz properly.

If the source is video (29.97fps interlaced), (omitting broadcast process here) the software player/hardware decodes MPEG-2, then creates a 59.94fps progressive video stream by *deinterlacing*. So the refresh rate should be set to 59.94Hz.
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