1 Reply Latest reply on Apr 26, 2010 6:15 AM by able123

    Interlacing

    robocop676

      Hi,

       

      There is an issue I can't understand. I have progressive footage from my digital still camera and after finishing my edits now I am going to export it to encore. As I know it, I have 2 options.

       

      1. From premiere CS4 direct linking to encore with transcoding the files in Encore. By this way, I guess the resulting DVD will be upper field interlaced in Encore.

      2. Or like I used to do it, I can export it as progressive mpeg-2 .m2v file. Then import these files to a new project in Encore. This way, the files won't be encoded again in Encore. So the result will be progressive DVD I guess.

       

      The resulting DVD will be watched on a regular TV, so will there be much quality difference between them? Do i have to interlace the progressive footage?

       

      Thanks in advance

        • 1. Re: Interlacing
          Level 4

          Hi...

           

          Here's some info from this link

           

          http://www.projectorcentral.com/hdtv_edtv.htm

           

          The Problem with Interlacing: Screen Size

           

          For most of the 50 years that the plain ole "525i" television has  been in existence, it has worked just fine. That's because TVs were  small. On a 19" TV set the picture looks great because the scan lines  and the errors introduced by interlacing are too small to see. But as  TVs have gotten larger, the scan lines have become more visible.

           

          Not only that, but the interlacing system creates weird "artifacts"  when blown up to big-screen proportions. When there is motion in the  picture, an object will have moved between the time the first half and  the second half of the frame are recorded by the video camera. That  makes straight lines break up and look like they've got jagged edges.  And on a 60" TV or a genuine large-screen image from a front projector,  the visible scan lines and jaggies can be enough to drive you nuts. Many  will remember the very poor picture quality from the earlier generation  big-screen TVs—if you sat too close to them you'd go blind in a hurry.

           

          The fact is that the 525-line interlaced system we have today was  invented in 1953 when televisions were small. The picture was never  designed to be blown up to large screen proportions. What works  beautifully at 19" is a disaster at 60". And TV designers and marketers  know that they couldn't continue to sell really bad video forever just  on the WOW factor of the screen size. So they came up with ways to clean  up the picture.

           

          The New Solutions

           

          The single largest step that was taken toward better big-screen video  is to eliminate the interlacing. Interlacing was originally invented to  save transmission bandwidth, since with an interlaced signal you only  need to send half the frame (either the even lines or the odd lines) at a  time. But now we have media such as DVD from which we can read and  transmit picture information much faster than ever before. So there is  no need to stay with an interlaced format.

           

          The alternative to the interlaced presentation of the odd and even  numbered lines is a process called progressive scanning.  Progressive scanning simply means that all of the lines in the frame of  video are painted onto the screen in sequential order from 1, 2, 3, 4, .  . . up to 480 in one pass. This has the potential to give us a cleaner  and more stable picture. However, the video signals are still being  broadcast in interlaced format, half the frame information at a time. So  the frames need to be assembled into full 480-line frames before they  can be painted progressively on the screen. This process is commonly  referred to as deinterlacing or line doubling (more on  this in a minute). This 480-line progressive scan technique is commonly  referred to as 480p. However, there is still the interframe gap, and  there are still 525 total lines. So some people call it 525p instead of  480p. But it's basically the same thing.

           

          Of course the marketers needed to come up with a snazzy name for this  simple new concept. So they did—Enhanced Definition Television, or  EDTV.

          EDTV is a major advance

          EDTV, or 480p, doesn't sound like much compared to HDTV. But it is in  fact a major step forward in picture quality. On a big screen it looks  closer in quality to HDTV than it does regular television. And it is  here today. Most DVD players on the market output both interlaced and  progressive signals, and they are getting better and cheaper by the  month. (At the moment, the Costco down the street is selling a little  progressive scan DVD player for $79.99). That means that every DVD movie  and video on the market can be played in EDTV right now.

          So here is your first absolute rule for buying a new video display,  whether it is a projector or a TV: make sure that it is 480p  compatible.

          But, you ask, what about regular interlaced video  sources like cable television, VCR, and so on—how do I play those  signals on a progressive scan video system?

          Well, no problem. You simply feed your new projector or TV the  interlaced signal just as you always did with your regular TV or VCR.  All of the newest video systems will accept interlaced signals as well  as progressive. They can do this because they have a device on board  called a deinterlacer or line doubler.

           

           

          Rod