All About HDTVs as a PC or Laptop Monitor

[Michael DeAbreu]

As I shopped for an HDTV, I got the uncomfortable feeling that few were PC friendly. Most new models sport HDMI inputs. Contrary to what I read in many AV magazines, HDMI isn't a backward compatible evolution of the DVI interface. This White Paper from the Video Electronics Standards Association (VESA) explains the incompatibility between personal computers and consumer electronics. In short:

A major contributing factor to this growing problem is the use of similar (and in some cases identical) digital interfaces used in both markets. Examples include the DVI and HDMI specifications, both of which are based on a common electrical interface definition and which are showing up more and more in both entertainment and PC systems. There is a growing likelihood of consumers having products of both types in their homes, and the apparent compatibility naturally leads the consumer to believe that such products will interoperate. However, due to the current incompatibilities between PC and CE industry standards and typical industry practices, a consumer attempting to connect CE and PC products will very often find that they do not work well together as expected.

The whole point of an HTPC is to connect it to a high definition display. Many people in this forum are having problems doing this. So, I thought I would start a thread that would specifically identify those high definition monitors and TVs that can't be connected to a PC or that do not allow the PC to use the panel's full native resolution.

[Michael DeAbreu]

Samsung LN series LCD TVs have an HDMI/DVI inputs which according to the User Manual cannot be used for a PC. Support for PC connectivity is actually quite good, even if not all digital. Instead it has an analog VGA PC input which supports a maximum resolution of 1360x768.

Applies to:
LN-R238W
LN-R237W
LN-R268W
LN-R2668W
LN-R267W
LN-R328W
LN-R3228W
LN-R327W

[Michael DeAbreu]

I was ready to buy the Sharp Aqous LC32D4U. That's the shiny black one with CableCard and ATSC tuner. Dealer then told me that a previous buyer couldn't hook up their PC to it through the HDMI input.

Poring through the manual gives no hint that it supports PC connectivity. Except for using a PC to control the TV through its RS-232 C serial port.

[Michael DeAbreu]

As a computer monitor, the Proview is limited to 1024x768 (XGA), 800x600 (SVGA) and 640x480 (VGA). The monitor is plug and play, but doesn't support the LCD panel's native resolution of 1366 x 768.

[hugh]

Excellent idea for a thread!

To clarify. should the subject say "List of Incompatible Personal Computer and HDTV's? I think it would be more instructive. If yes, just PM me and I will change the thread title

[57]

By way of clarification, there are many user manuals that say that the TV SHOULD not be used with a PC. There are several possible reasons.

1. Burn in on CRT-based and Plasma TVs.

2. A carryover from Burn in concerns, even though the particular model is not succeptible (ie the manuals are written for several models).

3. Concerns regarding a signal coming to the TV that could harm it from a PC. (I haven't heard of any harm to a TV due to a PC signal, but I have heard people say that it is "possible".

4. (Credit to Michael TLV) The manufacturers don't wish to field calls from people trying to connect their computers to their TVs since there can be 1000's of possibilities for synchs, etc.

[bobbinette]

I have a Toshiba 44HM85 which is a 720p native and I have hooked it to my Linux HTPC through a DVI to HDMI cable at the native 720p resolution. The result is very nice but the only real HD content I tried are HD .wmv samples from the Microsoft web site. The only problem I have with this setup is that I have a lot of overscan and I'm missing almost 1 inch of the image on every side, top and bottom. I can connect my HTPC through the RGB connection and correct the overscan but this way I'm limited to 640x480, 800x600 and 1024x768.

I have tried different 720p Modelines in my Linux video configuration but the overscan was always and issue. This page is a good reference for connecting a Linux computer to a HDTV. I have read that the "xvidtune" tool could help me create a custom configuration to cancel overscan but there may be some risk of damaging the TV! On the Windows side, The "Powerstrip" tool seems to be the most used to generate custom HDTV resolutions.

In the case of my HDTV, there is no indication in the manual about the possibility to use a computer with the native resolution of the TV but it is possible with the DVI->HDMI cable. So it is probably the same case with some other brand/model of HDTVs.

[57]

4-6% overscan is "normal" for many HDTVs. This doesn't help with HTPCs where you want no overscan. Perhaps Powerstrip can help your situation?

[Michael DeAbreu]

JVC HD-ILA 1080p

HD-56FH96
HD-61FH96
HD-70FH96

Unfortunately the full resolution of this HDTV is not available to HTPC users. According to the User Manual...

Pg 24
The digital-in terminal is not compatible with the picture signal of a personal computer

Pg 28-29
The PC connection is through the standard VGA D-Sub analog connector
Unfortunately it only supports VGA and XGA at 600Hz. Apple Macintosh computers are not supported

[WilJP]

Have you personally tested this or is it just the manual? What about component-in or other?

[Michael DeAbreu]

GRIDER in his thread found that with a little tweaking, it could be connected to a PC via the HDMI input. Because of overscan, the PC video output is set to 1840x1028 @ 30Hz (interleaved) even though the TV's native resolution is 1920 x 1080p.

The details are on the AVS Forum (start at post 181)

This isn't exactly plug-n-play and going by JVC''s own documentation you shouldn't be doing it. As 57 points out, this might be undue caution on the manufacturer's part. Nonetheless, I'll still consider this to be an incompatibility.

[testikoff]

I only can comment on RGB PC input of the HDTVs since I don't have a DVI out om my laptop.

All of the Sharp LCxxGDxU TVs that have DVI-I in only support 1280x720, 1280x768 and 1280x1024 resolutions over RGB portion of the DVI-I. The native resolutions of the panels in these TVs are 1366x768 (23, 26, 32, 37'') and 1920x1080 (45, 65'').

Sony Bravia KLVSxxA10 series TVs with native panel rez of 1366x768 support maximal PC input resolution of 1280x768 (the picture is centered & pillarboxed). However, Bravia XBR TVs support 1360x768 resolution over RGB input.

BenQ DV3750 LCD TV (1920x1080 panel) supports maximal RGB input resolution of 1360x768 (scaled up by the monitor to full screen size).

BTW all of the TV series mentioned (except Sharp's) I tested myself.

In my experience Samsung LCD HDTV monitors are the most consistent when it comes to PC input over RGB (HD15). They offer native panel resolution support and have plenty of adjustments for a PC monitor mode in their menus.

[Michael DeAbreu]

The User Manual doesn't explicitly warn user's not to use the HDMI input for a PC. However, the preferred connection is via the DVI or VGA inputs.

Although the native resolution of the panel is 1366 x 768 the PC compatibility chart only lists the following PC resolutions:

VGA: 640x400, 720x400, 640x480
WVGA: 848x480
SVGA: 800x600
XGA: 1024x768
WXGA: 1280x720, 1280x768
SXGA: 1280x1024

The TV cannot automatically distinguish between pairs of 4:3 and widescreen resolutions. The correct one must be set manually.

640x400 and 720x400
640x480 and 848x480
1024x768 and 1280x768

[jvincent]

I missed this thread earlier. It's a good idea to identify which HDTVs are easily supported.

As 57 pointed out, most of the warnings in the user manuals relate to either support or warranty concerns of the manufacturer.

However, it is possible to hook up an HTPC to ANY HDTV that has component inputs. Repeat, ANY HDTV with component inputs, irrespective of what the manual says. This will allow you to send 1080i or 720P to the TV, depending on what it supports.

The caveat here is that if you intend to use it as a computer desktop you need to be ready to mess around with all of the following: Powerstrip, your TV's service menu, and your PCs graphics card driver/configuration panel. This only applies to component inputs since there is no feedback from the TV to the graphics card via component so the graphics card will do what you tell it to and in the analog world of component, you can make this work with any HDTV. The question will be how much overscan you are left with.

Support for true PC connectivity, i.e. DVI, HDMI, or VGA is often trickier because the TV sets will report back supported resolutions to the graphics cards via the DDC interface and this will limit the graphics cards output capabilities. All is not lost however, as I believe most of the newer driver support the ability to ignore the DDC information, essentially allowing you to force whatever resolution you like. That being said, not all HDTVs will sync to a forced resolution.

[Michael DeAbreu]

In my opinion, to be PC compatible the HDTV should adhere to existing plug and play standards and work out of the box to it's full potential with no hassles.

All I'm saying is that we would never buy a computer monitor that had problems with "overscan", or that required us to use a utility like PowerStrip to guess at and match the monitor's scanning frequency, or that restricted us to using only 70% of the screen's native resolution or required us to hack the monitor's service menu or dicker with varoius driver configurations.

Nowadays, the cheapest LCD monitors support plug and play connectivity at PC resolutions and scan rates greater than those of an HDTV. So when I pay, $1000, $5000 or $10,000 for a TV, I don't think I should have to risk voiding my warranty or tying myself up in knots.

As for using a PC's component outputs, note that DVD's with macrovision protection cannot be upconverted to 720p or 1080i. Due to DRM restrictions, compliant video cards like ATI's and software like MCE restrict the component output to the DVD's native resolution of 480i/p.