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Discussion Starter · #1 ·
I'm beginning to realize that the more I read, the more questions I have. I have been fine with my setup for over 6 months now but now I have a question:


I'm running an HTPC with a 9500 Pro card using the DVI port to a SE 12sf DLP PJ (ScreenPlay 110). The PJ displays 848x480 as the signal detected. But on occasions you would see the setting set at 480p really quick and ends up the setting above. Now my question is, is this an interlaced setting? If so, is the DCDi proccessing being used? I always thought that if you don't use the s-video or composite, the DCDi won't be used by default. Up until now, I still think the HTPC and Theatertek is doing all the de-interlacing and sending the progressive picture to the PJ bypassing the DCDi. Can anyone confirm or shed light on this subject?
 

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The DCDi process de-interlaces, it require interlaced signals to work on. You are indeed bypassing your projector's processor when you feed it progressive image.
 

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Quote:
Originally posted by lsdavinci
I'm beginning to realize that the more I read, the more questions I have. I have been fine with my setup for over 6 months now but now I have a question:


I'm running an HTPC with a 9500 Pro card using the DVI port to a SE 12sf DLP PJ (ScreenPlay 110). The PJ displays 848x480 as the signal detected. But on occasions you would see the setting set at 480p really quick and ends up the setting above. Now my question is, is this an interlaced setting? If so, is the DCDi proccessing being used? I always thought that if you don't use the s-video or composite, the DCDi won't be used by default. Up until now, I still think the HTPC and Theatertek is doing all the de-interlacing and sending the progressive picture to the PJ bypassing the DCDi. Can anyone confirm or shed light on this subject?
Your HTPC and TheaterTek are reading the DVD, de-interlacing the data to progressive, and scaling.


DCDi is a de-interlace algorithm - and since the PJ is receiving a progressive signal - it is out of the loop.


Additionally, if you are watching a movie on DVD - for any given movie frame, the two interlaced fields come from the

same frame of the movie - and hence correspond to the same instant in time. De-interlacing a signal in which the two

fields come from the same movie frame is unambiguous - they just need to be "woven" together.


DCDi is only pertinent to material that was shot with a video camera, and hence was interlaced from the get go.
 

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Discussion Starter · #4 ·
So what I'm to understand here is that just because my PJ doesn't say 480p, the image is indeed still progressive. I always did assume this but after reading a few lines from this forum, I got a little curious.


Now this brings me to the next question, do you think the HTPC and TheaterTek does a better job than the onboard DCDi processor?
 

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Quote:
Originally posted by lsdavinci
So what I'm to understand here is that just because my PJ doesn't say 480p, the image is indeed still progressive. I always did assume this but after reading a few lines from this forum, I got a little curious.


Now this brings me to the next question, do you think the HTPC and TheaterTek does a better job than the onboard DCDi processor?
As explained in my last post - if you are watching movies on DVD - the DCDi algorithm is totally superfluous.


If the PJ is working correctly, if it sees a 480i signal that is properly tagged as film-based material, it should

bypass the DCDi algorithm and "weave" the fields together - properly accounting for 3:2 pulldown.


If the PJ were to invoke the DCDi algorithm on film-based material - it would only mess it up - since a "weave" is

the proper de-interlacing algorithm for film, not DCDi.


Depending on the projector, the de-interlacer may / may not be saavy enough to deal with 3:2 pulldown [ inverse telecine ].


An HTPC and TheaterTek certainly is saavy enough to properly deal with 3:2 pulldown. Short of a very high end stand-alone

scaler - an HTPC will beat most other scalers - including the vast majority that are internal to PJs.
 
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