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Discussion Starter · #1 ·
hi

i am using a htpc, ati 4650 card, to output to a 1280x720 projector. i am having problems noticably with HD material that causes a shimmer when the ati is set to 720p that almost disapears when changed to 1080i/p.

when set to 1080 does the pj downscale it to 720?

if so does that mean the pj is better at scaling than the pc?

i thought that setting the ati to 1280x720 gave a perfect pixel match or am i wrong?

would using say dscaler improve things or do i need a new pj?

thanks
 

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What make/model projector?

What is the native resolution of the HD material you are sending 720p or 1080i?

Is the PJ the only display on your system? If not how are the multiple displays configured?
 

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Discussion Starter · #3 ·
pj is a sanyo z4

hd is 1080 material, dont see any picture difference between 1080i or p apart from pj no longer offers progressive mode

pj is only display

most noticable scene is ch1 of batman where the distant tower block shimmers as do vertical lines

thanks
 

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Discussion Starter · #4 ·
ok so done some research and as the pj is native 720p then any input greater WILL be downscaled by the pj to its native res, in my case giving a better picture for 1080i material.

this begs the question WHY is the PC so bad at downscaling the 1080 material itself?

different software players make no difference and i have tried all the catalyst settings i can find

is there software that will do this?


i really dont want to have to keep swapping resolutions for hd viewing, to start with i cant read the menus etc cos the fonts are too small
 

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Most likely because the algorithims embedded in your graphics chip do not do as good a job of comnpensating for the 1 million pixels of detail being removed by adjusting the content of the adjacent pixels as the chips in your PJ do.

Also it is important to not that prior to being downscaled the 1080i input has to be de-interlaced to 1080p so a difference in de-interlacing algorithims is also important.

I do not know if there is any good downscaling software.
 

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Discussion Starter · #6 ·
thanks Walford v interesting

as said it would appear the pj does a better job of down downscaling

sending 1080i or 1080p to the pj makes no noticable difference, does this confirm the htpc does an equally good job of de-interlacing?

if so the only difference is then the downscaling which as said i find confusing as i thought the htpc did an excellent job of upscaling.

as i cant send out a 565i signal i cant compare scaling but i know the pc blows away a good quality dvd player
 

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Sending 1080i to the PJ just interlaces allready de-interlaced 1080p content so after it re de-interlaces it to downscale it would start with the same 1080p content.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by walford /forum/post/15511548


Sending 1080i to the PJ just interlaces allready de-interlaced 1080p content so after it re de-interlaces it to downscale it would start with the same 1080p content.

thats a lot of conversions

makes it even more confusing understanding why the pc is making such a hash of the 720p output as that is the most simplistic way of dealing with the issue . ie 1080i-1080p-720p.
 

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Your current ATI card has excellent scaling features.

Since you source material is 1080p I suggest that you continue to send 1080i/p to your PJ since the PJ apparently has better scaling hardware components then your PC card. Broadcastes use hardware scaling systems which cost many thousands of $ which is why SD programs broadcast over HD channels have much better PQ then the same program broadcast over SD channels on a HDTV.
 
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