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Not happy with my DVD-ROM screenshots

Discussion in 'Archived Threads 2001-2004' started by Brian Dobbs, Nov 21, 2002.

  1. Brian Dobbs

    Brian Dobbs Ambassador

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    I've taken a couple of screenshots of AOTC playing through my computer's DVD-ROM and I'm not pleased with the results. I'm trying to understand more about HTPC, but these results do not leave a good impression. What bothers me about the quality of the picture is the way curved and diagonal edges look. I've provided two pictures so you know what i'm talking about.
    1) STAR WARS logo - look at the diagonal lines in the middle of the the 'S' and on the sides of 'A' and you'll see what I mean.
    http://userpages.umbc.edu/~bdobbs1/PDVD_005.jpg
    2) Anakin and Padme - look at Padme's neck and Anakin's back and chin.
    http://userpages.umbc.edu/~bdobbs1/PDVD_015.jpg
    Can anyone tell me why the picture looks like this? Here are my specs.
    Video Card - nVidia RIVA TNT 2 Pro w/ 32 MB RAM
    Monitor - 1024 x 768
     
  2. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    It looks like an artifact caused by scaling the original 720x480 non-square pixel image to the square pixels of the display for proper viewing. It's duplicating about every 8th column of pixels, and that has to be the cheesiest, cheapest way to scale horizontally.
     
  3. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    So what would be the solution?

    Would he need to buy a descaler PCI card to do the work?

    Can you download a new software decoder?

    Or is there a utility out there that will solve the anti-aliasing/artifacts or what not.
     
  4. Josh Lowe

    Josh Lowe Screenwriter

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    That is strange. What software are you using? I have PowerDVD XP and have never had those kinds of problems. Those jaggies are caused by the picture being improperly resized.
     
  5. Vince Maskeeper

    Vince Maskeeper Producer

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    The big question is what software you're using.

    Another important point to remember is that if you're doing screen caps like this, they are decoded in the software realm- while real htpc uses hardware accelerated mpeg decoding on the card (Which is much better on ATI by the way) to provide the output everyone is excited about.

    -V
     
  6. Brian Dobbs

    Brian Dobbs Ambassador

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    I'm running Windows 2000 and using Power DVD v2.55. I didn't enlarge the picture as I took these shots, so that means I'm not even scaling them up and it's still having this problem.

    What's the difference between software and hardware decoding?
     
  7. Dave Sabo

    Dave Sabo Stunt Coordinator

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    How about the obvious... you're display is set to 32-bit color, correct? The second image almost looks like the banding you'll get from a lower colorspace.

    Also, make sure that what you're using to capture is set to capture in at least 24-bit color.
     
  8. Dave Sabo

    Dave Sabo Stunt Coordinator

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    Hey Brian, I just saw your sig... I had no idea Dream Theater was still together, that's awesome. I guess I'd assumed they wouldn't have been. Man, they were one of my favorite bands years ago. Images and Words is one of my all time favorite albums. I have to check some of their new stuff out. Is it still the original members?

    Sorry to get off-topic.
     
  9. Brian Dobbs

    Brian Dobbs Ambassador

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    You know, i usually keep my display to 16 bit color. I can use 32 bit, but i can't seem to notice any difference so I just use 16 bit. Maybe someone can tell me where to look to see a difference between 16 and 32 bit color? I assume using a lower bit depth would be less stressful on the video card right? Correct me if I'm wrong there.
    I'll have to go into Power DVD and make sure that I'm capturing at the highest bit depth. I'm at work now, so i'll check it later. Even if my bit depth wasn't optimal, how could that affect the quality of the edges from the picture?
    Dave S., wow you lost touch with DT?? They are still around and kicking so much a**. Seriously, they are still going strong and don't show any signs of retiring quite yet. In 1999 they had a concept album come out entitled Metropolis part II: Scenes From A Memory, then live DVD of the album played in it's entirety (oh man is this a must buy), and just this past January they had a double CD come out entitled Six Degrees of Inner Turbulence. The title track is over 42 minutes long but is one of the most incredible compositions ever created. Man have they evolved! To keep up to date, go to either dt.net's message board, or mp.com's message board. I check mp.com more often cause that's where most of the latest info comes up the quickest.
    http://www.mikeportnoy.com/forum
    and
    http://www.dreamtheater.net/bb/
    The current line up is as follows
    James LaBrie
    John Petrucci
    Mike Portnoy
    John Myung
    Jordan Rudess (3rd keyboard player - after Sherinian, who was after Moore. Rudess is so far the most advanced and melodic keyboard player around nowadays and makes the perfect fit in DT.)
     
  10. Wayne Bundrick

    Wayne Bundrick Cinematographer

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  11. Brian Dobbs

    Brian Dobbs Ambassador

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    Update....

    My roommate has a copy of Power DVD 4.0 that came with his new Dell computer. I installed it on my machine and looked at the scenes again. This version of Power DVD made the jaggies less noticeable. They were still there, but not quite as distracting. Unfortunately his copy of Power DVD won't let you capture screen shots for some reason. Maybe that it came with his computer has something to do with it. I played the disc on his computer, and he has a nVidia GeForce 4 64MB video card, and it looks much better on his computer. I really don't see any jaggies at all. Can anyone post screen shots of their copy of AOTC so i can compare?

    thanks
     
  12. Josh Lowe

    Josh Lowe Screenwriter

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  13. Brian Dobbs

    Brian Dobbs Ambassador

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    wow, those look great! How did you get them to a 960 x 540 pixel resolution?
     
  14. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    That's how PowerDVD XP 4.0 gives it to you when you view a DVD in a window.

    I think the reason that 480 lines are scaled to 540 is because that is one way of converting a 4:3 image to square pixels. The native 4:3 image is 720x480, and converting to square pixels requires either squeezing it horizontally to 640x480 or stretching it vertically to 720x540. Squeezing reduces detail so they stretch the vertical instead. Then, the corresponding 16:9 image would be 960x540.
     
  15. Brian Dobbs

    Brian Dobbs Ambassador

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    I installed the trial version of WinDVD, upped my color bit depth to 32 and took some shots. The results are much better.
    BAD - Power DVD v2.55
    http://userpages.umbc.edu/~bdobbs1/PDVD_005.jpg
    GOOD - WinDVD version 4 trial
    http://userpages.umbc.edu/~bdobbs1/cap001.jpg
    and
    BAD - Power DVD v2.55
    http://userpages.umbc.edu/~bdobbs1/PDVD_015.jpg
    GOOD - WinDVD version 4 trial
    http://userpages.umbc.edu/~bdobbs1/cap003.jpg
    So how do these new screen grabs compare now? I don't have a trained eye, but there doesn't appear to be much difference in quality between Wayne B's STAR WARS logo screen captures and my new ones. I've read Vince's review on Theatertek, and most likely will buy it if i choose to pursue HTPC, but how much better can the screen capture be? Vince, could you post a screen shot of the STAR WARS logo by using your THEATERTEK software?
    thanks
     
  16. Vince Maskeeper

    Vince Maskeeper Producer

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    I can later this week when I upgrade to the most recent versions (which does screen caps)- but I'd say that my actual picture performance is significantly better than the caps since using the dedicate MPEG engine on the ATI card in hardware mode looks at least 10-15% better than using the CPU for software based decoding.

    -Vince
     
  17. Brian Dobbs

    Brian Dobbs Ambassador

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  18. Wayne Bundrick

    Wayne Bundrick Cinematographer

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  19. Bruce Hedtke

    Bruce Hedtke Cinematographer

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    The "Good" shots compare favorably. Much, much improved.

    Bruce
     
  20. Dave Sabo

    Dave Sabo Stunt Coordinator

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    Brian,
    16bit doesn't produce all the colors that you're eye can see, you definately want 24bit to get all the colors. The most obvious degrading in images that you'll see with 16bit is banding in subtle blends of colors, there just aren't enough colors to make the transitions smooth. I worked as a retoucher for 12 years, color was my business. Banding was always an issue with digital images.
    On the Dream Theater subject... I guess I'm gonna have to catch up with their current stuff... and I'll definately check out their DVD [​IMG]
     

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