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SUBJECT: DEFINITIVE GUIDE: Displaying Custom Resolutions on HDTV!

FORUM: Home Theater Computers

DATE: 10-14-2000

STATUS: Originally posted on old UBBS system.

NOTE: This information predates the Radeon but also applies to Radeon


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MARK REJHON'S DEFINITIVE SUPERGUIDE:

DISPLAYING CUSTOM RESOLUTIONS ON A HDTV!

OCTOBER 2000 EDITION



Many people are tearing their heads off trying to get computer images on a HDTV set to display at anything higher than 640x480. I have decided that this needs a definitive guide!


This information guide supersedes the wonderful-but-now-outdated Mark J Foster's 1080i timings for HDTV (Nov 1999) as being the most detailed integrated guide on the Internet for a computer connected to a HDTV set. This guide will assist you in configuring a computer to work at very high resolutions via direct VGA output with ANY HDTV set (bypassing low resolution S-Video) even if the TV manufacturer says that their HDTV does not support computers!


Because of the newer PowerStrip 3.0 software, the HDTV modes that results from this thread will be MUCH more accurate than the ones from Mark J Fosters' original instructions which are based on older software. So if you were unable to get a HDTV picture displayed properly using the Nov 1999 instructions, try again using these instructions - you will find it a lot easier this time!


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GLOSSARY OF COMMON TERMS
  • Custom resolution: Ability to choose any computer resolution in single pixel increments. For example 1352x773 or 1360x1024.
  • Custom timings: Ability to change the scanrate without changing computer resolution, as well as modify the size of sync signals, to fit the specs of a particular display. This also includes ability to choose refresh rate in tiny fractions of a Hz.
  • Progressive scan: Display is done in a VGA-like fashion by drawing all the scan lines of an image one at a time, during one vertical refresh .
  • Interlaced: Display is done in a TV-like fashion by drawing odd-numbered scan lines in one vertical refresh, and even-numbered scan lines in the next vertical refresh.
  • positive/negative polarity: Some displays use positive or negative polarity for horizontal and vertical sync, while others can support both. Most computer monitors and high end CRT projectors work with any polarity combination. You usually will not need to worry about this.
  • Resolution-within-resolution: Also called "letterboxing" by some. VERY useful for HDTV televisions. A trick to allow displaying a computer mode on a display that cannot directly support the mode. For example, a HDTV set cannot natively do 1024x768, but it is possible to run 1024x768i in the middle of 1920x1080i for full HDTV compatibility while being able to play videogames that require standard computer resolutions. It can also be a way of solving excessive overscan on HDTV sets.
  • PowerStrip: Shareware computer software that allows you to adjust all the above. You can download version 2.X or later at www.entechtaiwan.com . Registered users may be able to obtain the PowerStrip 3.0 beta from Entech Taiwan for use at their own risk.
  • RGBHV: These are cables and jacks for Red, Green, Blue, Horizontal-Sync, and Vertical-Sync. The signal is identical to VGA, except that they are in 5 separate cables instead of a single VGA cable. HDTV can be done at full resolution over VGA or RGBHV.
  • YPbPr: This is component video, which many HDTV sets have. In order to connect a computer, you will need a converter to convert YPbPr into VGA.


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RECOMMENDED VIDEO CARD


Many video cards will work fine on a HDTV set at 640x480. However, GeForce series cards are the favourite here because:
  • They have sharper than average DVD picture (its VGA twice as sharp as Hollywood Plus VGA!)
  • They support custom resolutions, even 1352x773 at 93 Hz.
  • They support interlaced, so you can do 1080i
  • They have contrast/saturation/hue adjustments
  • They are very fast
  • They are great for 3D videogames too
  • They are very well supported in this forum
  • They can letterbox lower computer resolutions inside higher computer resolutions

Additionally, VGA/HDTV DVD picture quality varies from video card to video card. The best picture quality generally comes from GeForce cards. (ATI Radeon cards are great too BUT do not support custom resolutions at this time. So it's not a good option for HDTV set owners at this time!) For an example of picture quality difference between video cards, please see GeForce256 versus G400 review 1 and GeForce256 versus G400 review 2 . Many video cards have been tested, but none come as close in terms of BOTH flexibility *AND* picture quality. So, if you want the best, get a GeForce series card. The ultimate is currently the GeForce2 GTS (as of October 14, 2000).


Custom resolutions are essential in order to safely shatter the 640x480 barrier with a HDTV set.


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RECOMMENDED CABLES AND ADAPTORS


For best picture quality from a HDTV, you should never use "TV-Out", using S-Video or composite cables between your computer and HDTV set. Video over S-Video or composite is always 480i, even if you try to do 800x600. This is why text looks fuzzy and terrible - because computer video is downconverted to 480i by the RAMDAC chip behind the TV-Out, S-Video or composite jack.

You should always use VGA output to connect to a HDTV set. First, you need to determine what type of input that your HDTV set has any of the following (in order of preference, starting with the most preferable method):
  • RGBHV input jacks

    This is identical to VGA, but these jacks are better quality than the tiny 15-pin VGA jack, and will degrade the signal less. If your HDTV set uses RGBHV jacks, you only need an adaptor cable. Sometimes the jacks are BNC type, and sometimes the jacks are RCA type. You can buy high quality adaptor cables at BetterCables.com . If you are in a pinch or a hurry, and don't mind cables of somewhat less quality, you may be able to buy prefabricated 6-foot-length VGA-to-RGBHV BNC adaptor cables at your local computer stores, because they are used for high end 21" monitors. Many 21" monitors have RGBHV jacks, just like the rear of some HDTV sets, so some of your local high end computer stores, may stock them. Your business superstore might have them, but you may have to call around or hunt around. But remember: a 42-feet BetterCables.com cable produces less degradation than many of these store bought 6-feet cables!
  • Standard VGA input jack

    If so, then you've got is pretty easy! All you need is a plain vanilla VGA cable between your computer and your HDTV set. For the best quality VGA cable, purchase one from BetterCables.com !
  • YPbPr component video input jacks

    If your HDTV set uses only YPbPr component video inputs, you will need to purchase a converter box (such as an Audio Authority) to convert high resolution VGA into YPbPr that is compatible with your HDTV set. You will also, additionally, need the correct cable to connect your HTPC to the converter box, and then another cable to connect the converter box to the HDTV set. Please consult BetterCables.com for the right high-quality cables for your converter box situation with your specific brand of HDTV set.


Either way - the bottom line is that ANY HDTV set will work with a Home Theater Computer, provided you follow the above steps.


Information for further reading:
42 feet BetterCables.com cable better quality than 6 feet storebought VGA-to-RGBHV cable



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WHAT RESOLUTIONS ARE SUPPORTED BY A HDTV SET


Let me begin that you can often safely do 640x480 at 60 Hz from any PC on any HDTV set. If this is all you need, then you do not need to read the following.


You can output almost anything to a HDTV set, as long as the horizontal scanrate is 31.5 Khz or 33.75 Khz (or 45 Khz if your HDTV can do 720p), and the vertical refreshrate is 60 Hz. (30 Hz for interlaced) Just like the old adage, "You can have it in any color, as long as it is black!".


All HDTV sets can safely support 480p, 540p, 960i, and 1080i. If you are lucky enough to have a HDTV set that supports 720p too, then you can also do 1440i. Horizontal resolution is not important here, as the HDTV set can safely support any horizontal resolution (within certain restrictions, as will be explained later).


480p and 960i is 31.5 Khz horizontal scanrate

540p and 1080i is 33.75 Khz horizontal scanrate

720p and 1440i is 45 Khz horizontal scanrate


The letter "p" stands for progressive scan (non-interlaced).

The letter "i" stands for interlaced.

What is horizontal scanrate? Scanrate is the number of scanlines generated per second. As an example, 480p is actually 480 visible scanlines and 45 invisible scanlines (vertical blanking interval, or the "sync" interval) for a total of 525 scanlines generated per 480p refresh. There are 60 refreshes per second at 60 Hz. This means 525 scanlines times 60, equals 31500. There you go, that's 31.5 Khz horizontal scanrate!


You can do interlaced resolutions that have twice the number of scanlines as a progressive scan resolution. You can think of interlaced resolutions as being the same thing as progressive scan resolutions, except that every other refresh (this is called "fields") has the whole image offset downwards by half a scanline. So that the second 540p refresh "fills in the gaps" between the scanlines of the previous 540p refresh! So basically, two 540p fields combine to make a single 1080i image. At the same vertical refresh rate (per field), 540p and 1080i has the same horizontal and vertical scanrate - which means it is safe to do 540p on all HDTV sets that supports 1080i. As long as almost exactly the same number of scanlines are generated per second for both 540p and 1080i. The same goes for the other vertical resolutions.


A few early HDTV's can only do 1080i and NOT 480p. In this case, do not attempt to do 480p or 960i with these HDTV's, unless you put them inside 1080i timings. (Letterboxing 480p inside 540p is a recommended workaround).


Some HDTV sets are improperly advertised as being able to do 720p. BE VERY CAREFUL to make sure that this is done by the HDTV set, and not by the settop box! Some HDTV sets can only do 720p through a settop box (which converts 720p to 1080i). You should NOT attempt to try to use 720p timings. Use 480p/540p/960i/1080i timings instead with such HDTV's.


Horizontal resolution does not matter - you can display any horizontal resolution on a HDTV set. Also, it is possible to display lower vertical resolutions by letterboxing the computer resolution inside the middle of a higher computer resolution! Like doing 1024x768i in the middle of a 1920x1080i signal.


Further recommended reading:
Why 540p Equals 1080i to the electronics in a HDTV set
More explanations of 480p-540p-960i-1080i
Greg Roger's HDTV Information on CyberTheater


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MORE INFORMATION ABOUT INTERLACED HDTV VIDEO - AND WHY IT IS BAD FOR HTPC


Interlacing must be done for 960i and 1080i. However, interlacing is not good for computer text - this causes a lot of flickering! Also, most people prefer 480p or 540p when it comes to playing back DVD's on a HDTV set. Those who are lucky enough to have true 720p HDTV sets will prefer to use 720p for DVD playback.


Also, some GeForce cards do not do interlaced properly; they simply vibrate even scanlines up/down rather than interlace between both odd and even scanlines. This means you've lost half of vertical resolution, and the even scanlines are simply vertically pixel doubled. There should have been more vertical resolution during stationary computer desktop images (if the GeForce interlace was working properly). This may or may not be fixed in newer GeForce drivers or newer versions of PowerStrip. Currently, most people never try to do 960i or 1080i, especially for GeForce video card setups.


To clear up any confusion, HDTV always uses 60 Hz vertical refresh. This is the refresh rate that I will refer to throughout this document. For 480p, 540p, and 720p, there is no confusion - it is always 60 Hz.


However, for 1080i (and 960i or 1440i) there is some confusion. Some people say 1080i is 30 Hz, and other people say 1080i is 60 Hz. Both groups of people are correct - when you consider 1080i is all of the following:


30 full frames per second; and

60 fields per second (odd scanlines or even scanlines); and

60 vertical blanking intervals per second (60 sync signals per second).


This is exactly where the number 30 comes from. You may remember the old days where interlaced 1024x768i used IBM 8514-compatible computer monitors were referred to as 43.5 Hz or 87 Hz even though there is only one refresh rate for 1024x768i used on IBM 8514/A - this is precisely the same confusion occuring as well.


Most forum members prefer to refer to HDTV as always being 60.0 Hz. However, PowerStrip needs to be told to do 30 Hz when doing 960i or 1080i, even though there are actually 60 vertical blanking intervals per second. So we need to bear this in mind when adding interlaced resolutions to PowerStrip.


To keep your life easier - don't worry about interlaced resolutions. Worry only by adding progressive scan computer resolutions, such as 540p.


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POWERSTRIP: ESSENTIAL SOFTWARE FOR HTPC USERS WITH HDTV SETS


Let me begin that you can often safely do 640x480 at 60 Hz from any PC on any HDTV set. If this is all you need, then you do not need to read the following.


This makes it possible to "break the 640x480 barrier" on a HDTV set.

Ever dream of playing Unreal Tournament at sharp 1920x1080i from your HTPC?

Or playing DVD's upconverted to 960x540p?

This is when life get very interesting (or complicated)!


What makes this possible? PowerStrip! PowerStrip is a power user software program available from EntechTaiwan.com . It allows you to tweak your computer video card to the max, and do a lot of other useful stuff!


You can download a shareware version of PowerStrip. Unfortunately, it is only PowerStrip version 2.x. To do custom resolutions safely on a HDTV set, you must use PowerStrip 3.0. The instructions that follow in this article assumes that you are using PowerStrip 3.0. My instructions will not work on PowerStrip 2.x.


How do you get PowerStrip 3.0? Easy:
  1. You first register PowerStrip 2.x from EntechTaiwan.com .
  2. Next, you contact Entech Taiwan to obtain the PowerStrip 3.0.56 beta (or later) that is available for registered users.
  3. Install PowerStrip 3.0.56 into the same directory.
  4. Add a shortcut to the PowerStrip 3.0 executable to your StartUp folder of StartMenu->Programs, so that PowerStrip 3.0 loads everytime you boot your computer.


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DOING HDTV COMPATIBLE COMPUTER RESOLUTIONS WITH POWERSTRIP


Let me begin that you can often safely do 640x480 at 60 Hz from any PC on any HDTV set. If this is all you need, then you do not need to read the following.


As an exercise, we will begin by creating 960x540p. This will guide you through all the essential steps of using PowerStrip. These instructions are compatible with PowerStrip version 3.0.56 (October 15, 2000) and may be different with newer versions of PowerStrip. If so, please let me know and I will amend these instructions if I can.
  1. First, hook up an ordinary 15" or bigger computer monitor to your computer. Do NOT hook your computer up to your HDTV yet! You want to do your testing on a computer monitor first before connecting your HTPC to a HDTV set.
  2. Make sure PowerStrip 3.0 is installed and you see a PowerStrip icon in your Windows system tray next to your clock.
  3. Right-click on the PowerStrip icon and then select "Display Profiles"->"Configure".
  4. Click "Advanced Timings options..." button. (You might be startled at the airplane cockpit style screen that pops up. Don't worry too much. Do not touch anything in this screen yet.)
  5. Click "Custom Resolutions..." button
  6. Underneath New Resolution, enter the desired custom resolution.
    For this exercise, enter 960 in the first box (horizontal) and 540 in the second box (vertical)
    Note: If entering a number greater than 540 in the second box, you must enable the "Interlaced" checkbox right now at this point.
  7. Enter "60" as the Refresh Rate under "Vertical".
    Note: If you enabled the "Interlaced" checkbox, use "30" instead of "60"
  8. Click "Add new resolution"
  9. If your video driver supports the custom resolution, you will be prompted "The display driver has accepted the new resolution. Do you want to try to switch to the new resolution at this time?"
  10. Click "Yes"
  11. Click "Close". You're back to "Advanced timings options".
  12. Look at the "Total" number under "Vertical Geometry". There are two "Total" numbers, so make sure you are looking at the one under "Vertical" instead of "Horizontal".


    Vertical Total MUST be match 525 or 563. Use the smallest possible vertical total that is at least 5% bigger than your desired vertical computer resolution. This means the following:

    480p - Vertical Total must equal 525 lines (on 480p capable HDTVs)

    540p - Vertical Total must equal 563 lines (on 1080i capable HDTVs)

    720p - Vertical Total must equal 750 lines (on 720p capable HDTVs)

    960i - Vertical Total must equal 525 lines (on 480p capable HDTVs)

    1080i - Vertical Total must equal 563 lines (on 1080i capable HDTVs)

    1440i - Vertical Total must equal 751 lines (on 720p capable HDTVs)



    Increase or decrease the Vertical Total until it matches one of the above numbers.
    For the 960x540 exercise, make sure the Vertical Total is 563.
    Note: You are not restricted to computer resolutions matching 480/540/960/1080, as long as Vertical Total are 525 or 563. Basically, you will be letterboxing a computer resolution inside a higher resolution that is supported by your HDTV set. For example, 1024x768i centered in the middle of 1920x1080i. In this case, you need a Vertical Total of 563.
    Note: For your information, 960i/1080i is actually 951 and 1125 total lines respectively. But do not enter these in PowerStrip! The timings are per-field even when vertical scanrate is per-frame (30.0 during interlaced) - this is a confusing point! So enter 525 or 563 respectively for 960i/1080i instead.
    Note: For many video cards, interlaced resolutions work best when configured with an odd number of scanlines. This forces the GeForce card to do an even number of scanlines for one field and odd number of scanlines for the next field. Thus, the one-line difference between 720p and 1440i.
  13. Now look for "Refresh rate" (Vertical) and "Scan rate" (Horizontal).

    Increase or decrease these values until you get as close as possible to:

    Vertical Refresh Rate of 60.0 Hz ...(or 30.0 Hz for interlaced)

    Horizontal Scan Rate of 31.5 Khz or 33.75 Khz ...(or 48.0 Khz for 720p *if* supported)



    This means that:

    480p and 960i should use Horiz Scan Rate as close to 31.5 Khz as possible

    540p and 1080i should use Horiz Scan Rate as close to 33.75 Khz as possible

    720p and 1440i should use Horiz Scan Rate as close to 45.0 Khz as possible
    For the 960x540 exercise, aim for a 33.75 Khz horizontal scan rate.


    Your adjustments will often jump by counts of 0.3. Everytime you adjust one of these adjustments, it will affect the other. The two are interrelated! Just keep alternating between adjusting "Horiz Scanrate" and "Vertical Scanrate" in an attempt to get as close as possible to the above values!


    Try to get less than 0.1 away from the goal, so try:

    Vertical Refresh Rate between 59.9-60.1 (progressive) or 29.9-30.1 (interlaced)

    Horizontal Scan Rate between 31.4-31.6 for 480p or 960i

    Horizontal Scan Rate between 33.65-33.85 for 540p or 1080i

    Horizontal Scan Rate between 44.9-45.1 for 720p or 1440i (*if* true 720p is supported!)


    Otherwise, your HDTV may not be able to display anything! Your HDTV set has very, very, very, very fussy and tight tolerances.
  14. Click "Ok" at the bottom of Advanced timings options.
  15. Click "Save as" near the bottom of the PowerStrip Display dialog box under "Profiles".
  16. Enter the new name for the custom resolution.
  17. Click "Ok"
  18. Finally, disconnect the computer from the computer monitor and and connect to the HDTV set (do not turn off the computer when doing this!).
  19. Turn on the HDTV set.


Cross your fingers - your Windows Desktop should display itself after having adjusted the above! If the image looks stable, then go to the next section.


If you want to study another source of wonderful information about configuring a computer for a HDTV set, take a look at the Mark J Foster's 1080i timings for HDTV (Written November 1999). It is a great guide that still has very useful information. Be warned that some of the


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TWEAKING POWERSTRIP ON A HDTV SET


While the computer is connected to the HDTV set, you can go back to make adjustments by right-clicking on the PowerStrip icon and then select "Display Profiles"->"Configure" and then clicking "Advanced Timings options..." button. Do NOT make adjustments or click anything (except "Cancel" button) without being familiar with what you are clicking on - this advanced screen is very dangerous. A single click on the wrong number or button and your HDTV screen may blank out or screw up automatically. In this case, unplug the HTPC immediately (or turn off the HDTV set first, if faster to do so) Then re-connect your HTPC to your computer monitor. This is what you should do whenever something is wrong with the image on the HDTV set.


You may run into the following common problems with computer images on a HDTV set. Here are included solutions, in the order that you should follow:
  • Computer Image is too tall for HDTV set

    The proper way to fix this is to refer to the next section, "FIXING VERTICAL OVERSCAN/UNDERSCAN ON A HDTV DISPLAY".

    Important! Fixing this is somewhat cumbersome and requires creating a new custom computer resolution all over again. Try to live with it for now if possible - play a DVD for fun. You cannot safely fix this by adjusting PowerStrip vertical image size adjustment.
  • Computer image is too narrow or too wide for HDTV set.

    The proper way to fix this is to refer to the next section, "FIXING HORIZONTAL OVERSCAN/UNDERSCAN ON A HDTV DISPLAY". Important. You will need to readjust timings. But resist the temptation to use the PowerStrip picture size and position adjustment buttons!
  • Computer image does not appear or is badly distorted

    Unplug your HTPC from the HDTV set immediately! Connect your computer monitor back to the HTPC. Then you will need to follow steps 12 and 13 of the previous section, "DOING HDTV COMPATIBLE COMPUTER RESOLUTIONS WITH POWERSTRIP" to make sure that the VGA signal from your HTPC is as close as possible to HDTV specifications. If you can, try to get even closer than you were before, to 31.5/33.75 Khz horizontal scanrate (or 45.0 Khz for 720p HDTVs). If you fail, there are a few last resorts you can do while following steps 12 and 13 of the previous section:
    (A) Try the remedy for "Computer image is too narrow or too wide for HDTV set" listed above. Chances are that the horizontal retrace is well beyond spec of your HDTV set - this can happen when the computer image is too wide or too narrow.
    (B) Try changing the horizontal scanrate by a fraction of 1% - if you were a value close to 33.8 Khz before, try a value close to 33.7 Khz this time around. Do NOT go more than 1% below or above 31.5/33.75 Khz (and 45.0 Khz for 720p HDTV's).
    (C) Try adding one to eight pixels total to the horizontal front porch or back porch.
  • Computer image is flickering

    If you are doing interlaced resolutions such as 960i or 1080i, this is normal. There is nothing you can do about the flickering. Just make sure that you've followed the steps in the previous section correctly (especially critical steps 12 and 13!) If this is a non-interlaced resolution, then something is wrong and you should unplug the computer and replug your computer monitor into the HTPC.
  • Windows taskbar is 100% fully chopped off at bottom of screen

    Resize the Windows Taskbar by dragging its edge upwards, to make it thicker. If you cannot see the Windows Taskbar to do this, unplug the computer from the HDTV set and connect to your computer monitor. After you're done, reconnect to the HDTV set.
  • Computer image is offset towards the left or right

    Under "Position and size" click the left or right arrow to move your computer image leftwards or rightwards until it is centered (Ignore the other buttons; ignore the text that says "Pick up and move"). You can normally keep the computer connected to your HDTV set while doing this adjustment.
  • Computer image is not vertically centered

    Under "Position and size" click the up or down arrow to move your computer image upwards or downwards until it is centered vertically, until it has an equal amount of overscan at the top and bottom. (Ignore the other buttons; ignore the text that says "Pick up and move"). You can normally keep the computer connected to your HDTV set while doing this adjustment.


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FIXING HORIZONTAL OVERSCAN/UNDERSCAN ON A HDTV DISPLAY


IMPORTANT! Resist the temptation to resize the computer image while the computer is connected to the HDTV set. This is VERY important! Why? Because the procedure of resizing the image WILL change the horizontal and vertical scanrate. With most HDTV sets, you will experience frustration if you try to resize the image without testing on a regular computer monitor first.
  1. First, unplug the computer from the HDTV set and plug it into your compuer monitor.
  2. Right-clicking on the PowerStrip icon and then select "Display Profiles"->"Configure" and then clicking "Advanced Timings options..." button.
  3. Now, under "Position and size" click the sideways double arrow buttons (">
 

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Awesome document!


=============================================


>> If you want to study another source of

>> wonderful information about configuring a

>> computer for a HDTV set, take a look at the

>> __Mark J Foster's 1080i timings for HDTV__

>> (Written November 1999).


Unfortunately that link doesn't work anymore

since the forum seems to delete postings

older than a certain amount.
 

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Hello:


That is an excellent article!


Just one remaining question: The best resolution I'm likely to see with my Mitsubishi WS-55411 is going to be using 1080i timings. You mention setting up 1280 x 1024i, this is a horizontal to vertical size ratio of 1.25:1, yes? What about something that fills the HDTV screen completely? That is 16:9, like 1280 x 720? Is that achievable? Is anything higher likely?


Thank you,

Jeff
 
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