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PostPosted: Sun Feb 10, 2008 8:35 am 
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I just started looking at HDTV sets and am wondering what features you guys would point me to in a set specifically relating to mythtv.

I know nothing about the video input formats really. I'm assuming that HDTV output (looks like s-video but seems to have more pins) is the standard? What about DVI? Pros/cons of each? Are there others to consider?

Thanks for any suggestions.

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PostPosted: Sun Feb 10, 2008 9:01 am 
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Your usual best bets for connecting a computer to a HDTV for HDTV use is either VGA or DVI (if the TV has those inputs), or getting a DVI to HDMI cable and using a HDMI input on the TV.

The only other way to get a HD signal into a HDTV is a component cable (three RCA connectors, colored red green and blue). You can't send HD from anything via S-video (round connector) or composite cable (single yellow RCA).

Pros for using VGA or DVI inputs on a TV is that there's usually an audio connector associated with it, so it will play the computer's audio as well. That's the catch on using DVI to HDMI... the TV is expecting audio over HDMI as well and the simple DVI to HDMI cables don't do a thing about audio.

Of course if you're using an external audio amp, you may not care about TV audio.

The only other thing to watch out for is the input resolutions a TV accepts. Some 1080p TVs don't accept a 1080p signal via their VGA or DVI inputs. Check AVS Forums for specific TV models.


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PostPosted: Sun Feb 10, 2008 9:43 am 
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See http://www.mythtv.org/wiki/index.php/ComponentOut for a quick rundown.

You can expect to find VGA / Component / HDMI inputs on current TVs. Component and HDMI are digital, VGA is analog. Personally I would look to a DVI -> HDMI cable as ceenvee703 mentioned, unless you go with one of the nVIDIA cards with HDMI output (although I've read that audio over HDMI is not yet supported in the Linux drivers - http://forums.nvidia.com/index.php?showtopic=58215)


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PostPosted: Sun Feb 10, 2008 10:33 am 
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I would have said DVI->HDMI over VGA as well, except that with my new TV (an LG HDTV) the VGA signal looked great, worked fine at 1080p, and had ZERO overscan. DVI->HDMI has some overscan (I have to use the VGA input for my Xbox 360).


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PostPosted: Sun Feb 10, 2008 10:49 pm 
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You might want to read this info about 1 to 1 pixel mapping

http://www.avsforum.com/avs-vb/showthread.php?t=748074

it seems pretty important if I was going to buy a new Tv ...)


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PostPosted: Mon Feb 11, 2008 10:40 am 
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ceenvee703 wrote:
I would have said DVI->HDMI over VGA as well, except that with
my new TV (an LG HDTV) the VGA signal looked great, worked fine
at 1080p, and had ZERO overscan. DVI->HDMI has some overscan (I
have to use the VGA input for my Xbox 360).

I've been reviewing manuals while shopping for TVs (currently
LG is top on the list), and I believe that most current LG
models have a "PC mode" you can select that will eliminate
overscan an enable 1:1 pixel mapping on the HDMI input as long
as you're driving it at the native panel resolution. I found a
wiki page somewhere (the site was in the UK, IIRC), that seemed
to indicate that some older LG models had a 1:1 PC mode for VGA
inputs but not HDMI inputs.

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PostPosted: Mon Feb 11, 2008 5:05 pm 
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I got the LG 42LB5D and really like it. It was one of Consumer Reports' picks in the 42" LCD category. I checked the manual and the TV's menus and don't see an obvious way of setting the HDMI input I have the PC going into into the 1:1 pixel mapping mode. Nevertheless the overscan isn't horrible so I don't mind.


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PostPosted: Mon Feb 11, 2008 5:12 pm 
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ceenvee703 wrote:
I got the LG 42LB5D and really like it. It was one of Consumer Reports' picks in the 42" LCD category. I checked the manual and the TV's menus and don't see an obvious way of setting the HDMI input I have the PC going into into the 1:1 pixel mapping mode. Nevertheless the overscan isn't horrible so I don't mind.


That's disappointing.

At what resolution are you driving the display?

Here's the site that reports most recent LGs will do 1:1 via HDMI:

http://pixelmapping.wikispaces.com/LG+TVs

I'll have to check my downloaded users manual to see which model I was looking at.

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PostPosted: Mon Feb 11, 2008 6:42 pm 
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I stand happily corrected! Did some searching and it says you enable 1:1 mapping by setting the HDMI input label to "PC". Sure enough, once I did that things shifted and I have no more apparent overscan. Thanks!

PS: this is at 1920x1080p using the nVidia predefined HDTV modelines.


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PostPosted: Mon Feb 11, 2008 6:52 pm 
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ceenvee703 wrote:
I stand happily corrected! Did some searching and it says you
enable 1:1 mapping by setting the HDMI input label to "PC".
Sure enough, once I did that things shifted and I have no more
apparent overscan. Thanks!

PS: this is at 1920x1080p using the nVidia predefined HDTV
modelines.


Glad to hear it! I can order an LG without worry now. I've
been shocked at how hard it is to find out whether 1366x768 TVs
will do 1:1 at native resolution via HDMI. LG is one of the
few major brands that talks about it the manual (Sharp mentions
it, but it's rather confusing and not 100% obvious that 1:1
works on the HDMI input or just on the VGA input). Several
major brands (Toshiba is one that comes to mind) simply don't
support 1:1 on the HDMI inputs of their 768 line panels (it
seems to be more common on 1080 line panels).

Based on reports from users seems that almost all of the second
tier brand names like Olevia and Westinghouse do support 1:1
768p on HDMI, but their manuals are also pretty vague.


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PostPosted: Tue Feb 12, 2008 2:38 pm 
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ceenvee703 wrote:
I stand happily corrected! Did some searching and it says you enable 1:1 mapping by setting the HDMI input label to "PC". Sure enough, once I did that things shifted and I have no more apparent overscan. Thanks!

PS: this is at 1920x1080p using the nVidia predefined HDTV modelines.


Cool. Just curiously, what is your mythtv hardware for that set (processor and video board)? Also, how are you handleing your sound for the TV since HDMI sound doesn't work in LINUX (or so I've read).

Thanks!

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PostPosted: Tue Feb 12, 2008 2:54 pm 
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Location: Virginia, USA
graysky wrote:
Cool. Just curiously, what is your mythtv hardware for that set (processor and video board)? Also, how are you handleing your sound for the TV since HDMI sound doesn't work in LINUX (or so I've read).


My frontend/backend is over 3 years old... it's an Athlon XP 2400+ in a Chaintech 7NIF2 motherboard. It looks like I have a NVIDIA GeForce 6200? That's what /var/log/Xorg.0.log I think is telling me. Nothing very expensive, I think I paid $50 or so for it a few years back.

I can play back at 1920x1080p no problem with XvMC but it's unable to do the fade effects between menus so I've switched that off.

Digital audio is going out of an external USB device into my receiver, avoiding TV altogether.


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PostPosted: Tue Feb 12, 2008 4:11 pm 
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graysky wrote:
..... Also, how are you handling your sound for the TV since HDMI sound doesn't work in LINUX (or so I've read).

Thanks!
My Sharp Aquos 46D64 has one of the HDMI inputs with two analog RCA inputs to that HDMI input, so a PC sound plug to RCA 'Y' cord does the trick. The rest (2) HDMI inputs require the sound go in on the HDMI.


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PostPosted: Fri Feb 15, 2008 9:50 am 
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snaproll wrote:
graysky wrote:
.....Also, how are you handling your sound for the TV since
HDMI sound doesn't work in LINUX (or so I've read).
My Sharp Aquos 46D64 has one of the HDMI inputs with two analog
RCA inputs to that HDMI input, so a PC sound plug to RCA 'Y'
cord does the trick. The rest (2) HDMI inputs require the
sound go in on the HDMI.

That's the case for every HDTV I've looked at in the past
couple years. You can get a DVI+audio -> HDMI combiner box,
but they're not cheap. AFAICT, 99.9% of the HTPC crowd either
runs analog audio through the TV as described above, or runs
their audio (either analog or digital) through a separate amp.


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