CurtPalme.com Home Theater Forum

rs232guy · Joined: 30 Aug 2008 Posts: 5

There has been some interest on this forum and over at AVS in 1920x1080p72 (or 75hz) - to eliminate judder for film sources.

From what I've read, an HTPC is the easiest way to achieve this. Most (if not all) scalers will not output 1080p72, due to hardware bandwidth constraints. Some have discussed workarounds, with custom timings that fall within the 165Mhz limit. There are Blu-ray players and scalers that can output 1080p24 (and 25?) today. Some flat panel displays claim to accept 24p and produce 72hz or 120hz judder-free images. Please correct me if I am wrong so far on any of this.

The product I imagine would:
- Accept an HDMI input, up to 1080p60
- If the frame rate is standard 50 or 60hz, pass it through unchanged
- If the frame rate is 24hz (or 25hz), triple it to output 72hz (or 75hz)
- Output RGBHV analog

So I am wondering:
1) Would you be interested in this product?
2) Is it technically possible to build at a reasonable price?
3) Would anyone (like Moome or HDFury, etc.) be interested in producing this product?

One frame of 1920x1080 8-bit content is only 6MB (6,220,800 bytes) of memory. Theoretically, the delay could be no more than 1 (24hz) frame, or 40ms.

It seems to me like a 'frame rate tripler' would fill a specific unmet market niche. But I will defer to the experts (both users and technical wizards) on this thread. Wink

**kal** · Posted: Mon Sep 01, 2008 1:28 am Post subject:

This is certainly an interesting idea. Not sure of the feasibility of something like this but I've forwarded the request.

They way I see it, this could be a value-add to existing HDMI converters: If the input is 24 Hz then I could see the user having a switch or setting that lets you choose either x1, x2, x3, x4, or x5 refresh rate for the output. This would allow someone to take a 24Hz signal and output it at 48/72/96/120Hz.

And why stop at 1920x1080 (1080p)? Why not allow it for any resolution who's refresh rate is 24 or 25 Hz?

Kal

P.S. I'm 99% sure the reason something like this isn't done easily is because most HDMI converters are limited by what the IC they use can do. Yes, you can design chips or circuits to do absolutely anything but the cost goes up astronomically. Still a good idea however.

rs232guy · Joined: 30 Aug 2008 Posts: 5

Thanks for your response, Kal - and for passing this idea on!

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

It would be a neat idea to add after VP too, since most go up to only about 60hz at 1080p. the only scaler i know to go higher is the new Tv-Ones that have been overclocked to close to 200mhz, they tried 1080p@85hz just for "fun".

Athanasios

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Yeah, I wished for a tripler like this quite a while ago. Nobody jumped on the idea, though.

rs232guy, it's certainly possible to implement stuff in an FPGA. But you've just dramatically increased the effort and complexity of the project if you do that. Not only do you have the hardware design, now you've got to design the programming of the FPGA -- NOT a trivial job.

**AnalogRocks** · Posted: Mon Sep 01, 2008 5:38 am Post subject:

Wonder if you can do it with an analog circuit?

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

http://www.avsforum.com/avs-vb/showthread.php?t=1057629

Seems that Prehjan has inputcard on his marquee that does framedoubling..Sounds very special Rolling Eyes

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

Not sure if there are 1080p-capable capture cards for PCs that are any kind of reasonable price, but if so you could build a pretty cheap (for the PC components) PC-based solution - build it on a light RTOS. Then it'd be pretty easy to implement various scaling features too, and it would basically be a software / packaging problem.

There's at least one company that claims to have such a card for $250, so you could probably throw this together for a reasonable amount of money (Depending on what that is - you'd still be looking at a $2k price on the low end), plus have nifty on-screen menus, custom timing, and so forth.

If fifty people want one, I'll build 'em. Wink

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

SisterOfMercy · Posted: Thu Nov 20, 2008 5:01 pm Post subject:

I don't think the Lumagen HDP does 1080p72.

It seems to be limited to 150 MHz:
http://www.avsforum.com/avs-vb/showthread.php?t=808591

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

SisterOfMercy · Posted: Thu Nov 20, 2008 7:38 pm Post subject:

Because we can? For PAL material I'd like to watch 1080p75. The PJ might not be as sharp at that resolution, but the scaler can't do it at all. It would be nice if you don't run into bandwidth problems with the stuff before the PJ.

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

SisterOfMercy · Posted: Thu Nov 20, 2008 10:10 pm Post subject:

No. It might, but I can't see it because of the scaler limitation.

Come to think of it, it doesn't matter at all what my display can do or can not do. We want to convert any material (video and film based, SD, HD, whatever) to 1920 x 1080 @ 75 Hz and beyond. That's the problem, not whether it is necessary or not. That's not interesting at all.

Person99 · Joined: 09 Mar 2006 Posts: 4899 Location: Flower Mound, TX

SisterOfMercy · Posted: Thu Nov 20, 2008 10:40 pm Post subject:

Oh please, no car analogies. I've read enough of those. Sad

Mark_A_W · Posted: Mon Dec 08, 2008 5:16 am Post subject:

At 1080p 72hz you will need custom porches. A simple tripler will not work.

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

I'd have to agree with Person99, and just what PJs are going to be able to use a 1080P/72hz signal without it looking very very soft. BW folks, it takes lots of BW to use that and I know of none that will including stock cine9 boards. Even my modded boards or Gregs or MPs won't handle this.