www.hometheaterhifi.com/volume_7_4/dvd-benchmark-part-5-progressive-10-2000.html
Great material tends to look fine on just about every player, and we find ourselves squinting and striving to tease out the tiny differences in sharpness and resolution. But, as you will see from this article, there are really substantial differences in how well players handle badly encoded DVDs. There are plenty of DVD player reviews that will tell you how terrific a player looks when playing The Fifth Element or Starship Troopers, but really, that's like testing a car by only driving it on a perfectly smooth, level road. We're going off-road and showing you how well these players handle the rocks and potholes. This article is all about problems you might encounter with progressive DVD players, when you will encounter them, and what those problems look like. We took most of the currently available mass-market progressive DVD players, and a few expensive boutique players, along with some PC DVD software, and tested them with the most difficult DVDs we could find. It almost goes without saying that all of these players will deliver a very nice image when fed good material (with a few exceptions, which we'll cover later). There are differences between the players' basic image quality, but for the most part, you're going to notice very minor video quality differences when the players are firing on all cylinders. When the players are dealing with a crummy DVD, though, that's when things get interesting. Many people wonder how important these hiccups and glitches really are, and why we spend so much time and energy testing for them. This is a difficult issue, and depending on how you ask the question, you can get several different answers. That represented our best guess as to how often these glitches intruded, based on our experiences watching a lot of movies. Since then, we've done a lot more research and discovered that nearly all movies have at least some glitches. Sometimes the glitches are very minor, and will trip up only a few DVD players, and then only for a couple of frames. Sometimes they last longer, and extensive sections will be messed up on many DVD players. Sometimes a section has glitches, but is not a particularly revealing scene for deinterlacing problems, so most viewers will never notice that their player isn't giving them the correct picture. Other times the scene is messed up in really obvious ways. The biggest problem is that most people don't know that it's the DVD player. People assume their DVD player "just works" and thus when they see a deinterlacing glitch or other problem, they are most likely to assume it's just the DVD transfer (the movie disc). Many current progressive players fall back into a very watchable but very soft video mode when they aren't sure whether the source is film or not. In the worst case, the entire film will look excessively soft, which means they're getting exactly no benefit at all from their progressive player. They're being sold a bill of goods, because their player isn't delivering the crisp film image they were promised. We think the user should demand a player that "just works fine," and that is what our tests revolve around. We think you should be able to just drop in a disc and get a great, crisp, full-resolution image. It shouldn't matter whether the encoding software on the front end is buggy, or the disc manufacturer cut corners, or whether the original material was shot on film or NTSC video or HD progressive video, or some kind of film/video/computer hybrid. If you think that standard is not worth working towards, you're reading the wrong article. To answer the original question about how important these tests are, we think that our deinterlacing tests are relevant to everyone - including studios, manufacturers, and consumers - no matter what movies you watch. If you care about getting the best picture all the time, not just when the disc is mastered perfectly, then you should care about these tests. And if you watch any low-budget films, animation, documentaries, TV shows on DVD, concerts, or kid's videos, you should care about these tests a lot. We also want to warn you: if you have a progressive-scan DVD player that you are happy with, you probably should not read this report. With some of these artifacts, you are much better off not knowing they are there, because once you start to notice them, they'll drive you nuts, and then you will inevitably want to replace your player. Once someone points out a flaw in your player, it's very difficult to ignore it. If you don't have a progressive player, and are thinking about getting one, then this report is for you. Or if you have a progressive player, and are seeing artifacts that are bothering you, and you want to find out more about those artifacts, or find a player that doesn't have them, then again, this is a report you will want to read. But the rest of you: don't blame us if reading this article ruins your enjoyment of your expensive DVD player. If you want a review that will tell you, "Oh yes, this is a reference quality player," for most players, there are plenty of A/V magazines out there to do that for you. Before we begin, Brian Florian will explain how film is transferred to video. The Nature of Interlaced TV, Film-to-Video Conversion, and Other Interesting Gambits To better understand the upcoming concepts on Progressive Scan DVD Players, one must first be armed with some basic knowledge of how the NTSC television system works, how film gets transposed to it, and how all that relates to the newer progressive scan television displays. The following information is not intended to be a definitive paper on the subject, but should serve as a good introduction for all. The visuals and animations presented here, though large in file size, are key and will reward repeat viewing. Motion pictures are comprised not of motion at all, but numerous stills shown in rapid succession. For the films we all watch at the theater, 24 frames are shown in one second (24 frames per second, or 24fps). The NTSC television system generates its visuals in a very different fashion . The resultant images that make up the motion picture are comprised of alternating interlaced fields: that is, one field consists of all the odd lines (1,3,5 etc. The result is that only half of the video's display is drawn every 60th of a second. Traditional talk quotes NTSC television as having 30 frames per second, each being comprised of two interlaced fields. The NTSC interlaced system shows 60 unique images (fields) per second, and each field is an independent snapshot in time. So we don't want to think of interlaced televisions in terms of frames but rather in terms of fields, interlaced fields, and 60 of them per second. As long as nothing in the picture changes (such as when showing a still image), the alternating fields will actually complement each other and form a complete picture. The display will flicker and scan lines will be visible (both a inherent of an interlaced system), but that's life in an interlaced world. We don't spend the evening looking at a still picture on the TV though. The moment something moves, we get interlacing artifacts! Remember we said each field is a unique snapshot in time. When there is motion, the subject will be in one position for one field, and in another position for the next. The alternating fields no longer complement each other and we have a bit of a mess. Each field shows the tomato a little farther to the right than the previous. Because the fields are interlaced, jagged vertical edges can't help but exist, except during for the last two fields (5 and 6) where the tomato is stationary (and being that the subject is stationary, the fields complement each other). The further back you are from an interlaced display (or the smaller the display is), the less this and other artifacts are noticed. If you want to see the effect in real life, get yourself a little too close to an interlaced TV. Focus in on an object's edge that is stationary and wait for it to move. Not only is the flicker of the rapidly alternating fields annoying, but have a good look at the ski-pole: It comes and goes because it's so fine it can only b...
|
http://csua.com/feed/