Screen Refresh Rates For High-Def TV

[CyberSimian]

Is there anyone who uses HDMI to drive their TV with 1920x1080 at 50Hz (UK, Europe), or with 1920x1080 at 60Hz (USA, Canada)? If you do, what graphics card and TV are you using?

The reason I ask this is that my Nvidia 8600GTS connected to my Toshiba 32WL56 allows me to choose 1920x1080, but does not offer me 50Hz; it offers only 25Hz or 30Hz. I really, really, really do not want to use 25Hz, as it gives jerky movement on TV pictures (it is OK for the Windows desktop). Thanks for any info.

-- from CyberSimian in the UK

[richard1980]

I drive mine at 1920x1080 at 59.94 Hz. Using an NVIDIA GeForce 9300. Your TV doesn't offer 50 Hz because 1920x1080 at 50 Hz is 1080p. Your TV is only capable of 1080i or 720p, not 1080p.

[holidayboy]

I'm using 1080p@50Hz

I used to have issues with weird colour reproduction with my AMD card at 50Hz but now that I'm using an Nvidia GT430 everything looks good.

I'm outputting straight to a 40" Samsung LCD TV (LE40A656A I think).

Is your TV a 1080i model maybe?

[richard1980]

I looked up the specs on his TV and confirmed that it is only 1080i/720p. Sounds like a good excuse to buy a new TV

[newfiend]

Its a great excuse, but try getting that past the wife... Unless it "totally stops working".. Good luck! (at least in my house anyway..).

Sent from my WP7 using Board Express

[barnabas1969]

Just throw a toy car at it and blame the kids!

[newfiend]

Just throw a toy car at it and blame the kids!

DAMN THOSE KIDS!!! HAHA!!

[CyberSimian]

Your TV doesn't offer 50 Hz because 1920x1080 at 50 Hz is 1080p. Your TV is only capable of 1080i or 720p, not 1080p.

Thank you Richard, you have hit the nail on the head. I had not appreciated the significance of the distinction between 1080i and 1080p with regard to the refresh rates that were supported.

My HTPC is currently using a resolution based on 1280x720, as that is the highest resolution that allows me to choose 50Hz refresh. The Nvidia Control Panel labels this resolution as "720p". As my TV has no built-in "suppress overscan" setting, I created a custom size in the Nvidia Control Panel to eliminate overscan, so the actual dimensions in use turn out to be 1228x690 (that gives me one or two pixels of overscan along each edge -- enough to ensure that bright random pixels that sometimes occur at the extreme edges of DVD video are just off-screen).

I tried the 1920x1080 setting out of curiosity. I have been toying with the idea of getting a true high-definition TV, but was concerned that I might still be limited to 25Hz refresh. Now I know what to look for to be sure of getting 50Hz refresh. Many thanks,

-- from CyberSimian in the UK

PS: And thanks to all of the others who responded.

[winterescape]

On a 32 inch TV you can’t tell the difference between 720P and 1080P, save your money. (Unless you sit like 6 inches from it) You have the best configuration for that display.

[richard1980]

That's a good point that I completely missed. You would actually have to sit no more than about 4.2 feet from the TV to be able to resolve a 1920x1080 image.

[barnabas1969]

I agree. And I'll add that your best picture depends on which device has the best scaler built into it. Also, if you scale the material more than once, you may degrade the picture quality.

For example, let's say that your source device can output 720p, 1080i, or 1080p. If the source MATERIAL differs from the source DEVICE's output resolution, then the source device will need to scale the material to match the output. Then, if the output resolution does not match the TV's NATIVE resolution, the TV will then need to scale it again.

If the TV has an EXCELLENT scaler built-in, then you should make the source device output whatever resolution the source material is recorded in. Of course, only your eyes can judge which device has the best scaler.

The problem is that not all source material is in the same resolution. For example, in the U.S., CBS is 1080i, but ABC is 720p. So, if your TV is 720p, and you make your source device output 1080i, ABC will get scaled 720p -> 1080i -> 720p.

The most likely best-choice is to make the source device output the native resolution of the display. So, if the TV has a native resolution of 720p, then the PC should output 720p. The PC's graphics card will scale 1080i source material to 720p... resulting in a single re-scale of the material. However, as I wrote above, your eyes need to be the judge. And... on a 32 inch display, it's unlikely that you can tell the difference unless you sit VERY close to the screen.

[CyberSimian]

Some interesting points; thank you.

I have not yet decided whether to get a new TV, but if I do there would be three reasons for doing so:

(1) Bigger screen. My current Toshiba is a 32-inch, which seemed enormous when I first got it in 2006, but that was stepping up from a 24-inch CRT. Nowadays, 32-inch seems quite pedestrian. Any new TV would certainly be in the 40's... a 46-inch perhaps.

(2) True high-def (1080p). None of this "poor-man's high def" (720p) for me!

(3) A DVB tuner. The Toshiba was (I think) the last model that Toshiba marketed in the UK that had only an analogue tuner. Although I rarely watch live TV these days, a built-in DVB-T2 tuner would be a useful standby for when Media Center starts having tantrums. (There are no longer any analogue TV broadcasts at my location in the UK.)

And finally, of course, let us remember that we are all obligated to spend, spend, spend, in order to help the economy climb out of recession. (Go on, buy that piece of shiny new high-tech that you have always promised yourself; you know it makes sense!)

-- from CyberSimian in the UK

[winterescape]

Both posts above add good points. The content and scaling is another issue that is not well understood. On the resolution topic, for your eye to perceive the difference between 720P and 1080P you need to go bigger than 42” AND have content that is higher resolution. This graph might help …
http://s3.carltonbale.com/resolution_chart.html

[makryger]

I like that resolution chart... haven't looked at one since 4K was introduced through.

Just goes to show that for the vast majority of users, 720p will be sufficient. But if you happen to have a larger TV (60" and higher, than 1080p becomes noticeably better. The 4K resolutions may be great for movie theaters or projectors, but most users won't find it any better.

Although, as someone who makes logos for really small spaces, I'd jump at the chance to have double the pixels to work with. Even if the user doesn't notice it, I Sometimes stare at my 46" screen from a few inches a way to inspect logos...

[richard1980]

for your eye to perceive the difference between 720P and 1080P you need to go bigger than 42” AND have content that is higher resolution

It doesn't matter how big the screen is. Every screen size has a viewing distance where 1080p can be distinguished from 720p....you just have to be sure to place the screen no further away than that distance. It doesn't matter if it's a 60 inch plasma TV, a 42 inch LCD TV, or a 21 inch computer monitor.

[makryger]

for your eye to perceive the difference between 720P and 1080P you need to go bigger than 42” AND have content that is higher resolution

It doesn't matter how big the screen is. Every screen size has a viewing distance where 1080p can be distinguished from 720p....you just have to be sure to place the screen no further away than that distance. It doesn't matter if it's a 60 inch plasma TV, a 42 inch LCD TV, or a 21 inch computer monitor.

..I'm assuming that winterescape is assuming a "normal" viewing distance of about 10 feet.

[barnabas1969]

In my last house (pre-divorce), I had a 110" tab-tensioned, motorized projection screen. My seating position was 17 feet from the screen. In my current house (post-divorce), my room isn't big enough for that. I have a 64" plasma now. I sit 12 feet from the screen. Honestly, I'd like to go a little larger, but a projector isn't feasible in my viewing room... and I really wanted a plasma this time. It's a 1080p miracle of technology... a truly "smart" TV. It's gorgeous... and I can tell the difference between 1080p and 720p.

[winterescape]

for your eye to perceive the difference between 720P and 1080P you need to go bigger than 42” AND have content that is higher resolution

It doesn't matter how big the screen is. Every screen size has a viewing distance where 1080p can be distinguished from 720p....you just have to be sure to place the screen no further away than that distance. It doesn't matter if it's a 60 inch plasma TV, a 42 inch LCD TV, or a 21 inch computer monitor.

..I'm assuming that winterescape is assuming a "normal" viewing distance of about 10 feet.

Thanks for clearing up what I assumed was obvious from the link to the chart I posted… Of my statistically insignificant sample of HTPC users (all 6) have 8-10Ft viewing distance.

And Yes, I can see why you would like more pixels but I would guess you are atypical of the majority with your viewing distance