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Life after 56Hz ...

markhudds2

Active Member
Some interesting reading for HTPC users with Sony projectors (models prior to HS50/51)....

After being happy for many years with Sony widescreen projectors (WVL-400QM, VPL-VW11HT and VPL-VW12HT) and HTPC rigs set-up at a native resolution/refresh of 1366x768/56Hz, I've started to become more and more critical of the pan smoothness on films especially now that HD seems to exhibit more of a problem.

Of course the issue is with the well-known limitation of the Sony's native resolution refresh of 56Hz not being film/video friendly (not a multipe of 24, 25 or 30). I've managed to live with the set-up until now on the basis that driving the projector at native res was the most important factor to bypass it's internal scaler and that slightly less than perfect pans were acceptable. I viewed a friends set-up using a stand-alone DVD player and although the projected image was no where near my Theatertek/FFDshow resize combo, I realised just how much smooth pans added to the film experience. Time for some experimenting ....

As my Sony VPL-VW12HT reverts to 4:3 aspect in 'computer' mode when using any resolution/refresh other than 1366x768/56Hz, I set my input to 'Video-GBR' mode. According to the instructions, this mode accepted the common HDTV signals.

Not wanting to upscale 720p to the panel res, I aimed at getting 1080i working which could be downscaled to the panel res. First I tried 1920x1080i/30hz - although the projector accepts this (flags as 'HDTV) it gives massive overscan and therefore all the desktop isn't shown. I then found that a popular setting for a non-overscanned 1080i signal was 1776x1000i/30Hz - I tried this (via powerstrip) and with a bit of fiddling with the H-SIZE and H-POS and V-POS settings on the projector, I got a very pleasing picture with the entire desktop. Not quite as sharp as native res but not far off. I then tried some film/video material after setting my FFDShow resize to 1776x1000 ... wow, I got a perfect, fuild, smooth picture ... quite a success! I can only conclude that the VPL-VW12HT internal scaler is really quite good and does a great job of downscaling to native.

I went on to try 25Hz and 24Hz settings at the 1776x1000i resolution and although they were both correctly flagged by the projector as 1080i/50 and 1080/ps24f, I couldn't get the same film smoothness as the 30Hz refresh. This was the case even for PAL material - why on earth would PAL be more smooth at 30Hz interlaced rather than 25Hz interlaced? Simarly for NTSC film material - why would this be better at 30Hz rather than 24Hz?

I wasn't too concerned with 24Hz as it did show flickering when close to the screen and the projector does pulldown anyway for NTSC (CINE-MOTION set to 'auto).

So advice to Sony owners - if you're using your HTPC for mainly movie watching and don't mind losing a bit of sharpness from your desktop then I would say try 1776x1000i/30Hz rather than native res. Of course you could always switch between 'computer mode' using native and 'video-gbr' mode using 1776x1000, although it's quite a few button presses through the projectors menu!
 
D

DaveP

Guest
Thanks for that Mark. I think I shall give that a try, it may help with the 6 Nations Rugby this weekend! (Sky+ to Sweetspot/Dscaler then nVidia 6600 DVI to my Sony HS20)
 

markhudds2

Active Member
No probs Dave.

Let me know how you get on with 1080i/50.

Can anyone offer an explanation as to why I see judder when running PAL material at 1080i/50 and yet PAL at 1080i/60 is smooth? :confused:
 

drummerjohn

Well-known Member
Weird... I have a 10HT and have tried lots of resolutions\refresh rates. Im a PAL person btw. Trust me when I say I am horrendously critical of poor pans.

1080i @ 50Hz (1920x1080) = unacceptable overscan but was perfectly smooth.
720 @ 50HZ (1280x720) = unacceptable overscan but was perfectly smooth
720 @ 50Hz (1184x666) = no overscan and perfect pans.

I initially fed my 10HT with a 720p @ 60hz and panning was dreadful.

I will try your settings tonight.

Just to add - I dont understand how the 10HT can have a refresh rate of 56Hz. That means PAL wouldn't work. I've examined it in detail using Reclocks scrolling bar and other tools. It doesnt make sense.
 

markhudds2

Active Member
drummerjohn said:
Just to add - I dont understand how the 10HT can have a refresh rate of 56Hz. That means PAL wouldn't work. I've examined it in detail using Reclocks scrolling bar and other tools. It doesnt make sense.

That'll be because the 56Hz doesn't apply to the 10HT ... just the 11HT, 12HT, HS10 and HS20? ...

Sony, in their wisdom, didn't allow the 10HT to be fed native resolution so they corrected that in the subsequent models however they still messed up as the 1366x768 native mode (WXGA - think it's mode '51' in the instructions) can only be acheived if the refresh is 56Hz :suicide:

Any deviation from 56Hz, in computer mode, results in fallback to 4:3 ratio.
 

Mr.D

Distinguished Member
I prefer the [email protected] mode to any of the others with the exception of [email protected] for NTSC field based material.

Its way sharper than the fudged 1776 res.

PAL at 56Hz results in regular repeated frames that are little different to 3:2 pulldown ( or rather 24fps with regular frame repeats to bring it to 30fps).

If anything film based NTSC material ( assuming its been deinterlaced correctly) has even less judder than at 60Hz as its only 4 frame repeats per second instead of 6.

i'd rather have the sharpness than the slightly smoother playback. Film strobes a little anyway , I think a lot of people mistake natural strobing for a refresh issue.
 

markhudds2

Active Member
Keith - I would argue that you only lose sharpness when viewing the desktop.

To my eyes the downscaled 1776x1000 ffdshow resized image actually looks sharper when viewing material than a native 1366x768 ffdshow resized image.

I'll be doing some more comparisons at the weekend...
 

markhudds2

Active Member
Mr.D said:
I ran with 1776x1000 for about a week when I first got my HS20 ...won't be going back to it.

Strange, I just can't see any decreased sharpness (when viewing material) at 1776x1000. Do you think the HT series have a better on board scaler than the HS series and that's why the 12HT was twice the price of the HS10/20? If so that would probably explain the differences at 1776x1000 ???
 

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