On Mon, 04 Dec 2006 17:05:49 +0100 Harm Weidmann <[EMAIL PROTECTED]> wrote:
> http://www.schenck.de/dvdimg/seq0frame0001.jpg Ah. I can tell you why you get the flickering. Nicolas might have provided you with a command line to fix it; I haven't bothered to find out exactly what it does, but it's not commented. The problem lies in the difference between your monitor and your TV; your monitor is a progressive display, while your TV is interlaced. And your image contains text containing single pixel rows of black on gray. Progressive display: ---------------top-of-image----- 1: ........ 2: ...**... 3: .**..**. 4: .**..**. 5: .******. 6: .**..**. 7: .**..**. 8: ........ Each line is displayed after each other, once for each frame update. Nice image. Interlacing is a completely different beast. In order to save bandwith, each frame was divided into two fields, which are transmitted, and thus displayed, after each other. Each of these fields contain half the number of the frame's lines: Field 1: ---------------top-of-image----- 1: ........ 3: .**..**. 5: .******. 7: .**..**. Field 2: ---------------top-of-image----- 2: ...**... 4: .**..**. 6: .**..**. 8: ........ Note that the first field start right at the top of the image, while the second start a wee bit down from it (half a line, actually). The effect is that the eye sees an image with twice the vertical resolution, while glossing over the fact that the image is jumping and really weird in a number of ways. What happens when single pixel lines are displayed in this manner is that they only show up once every other _field_, which makes for a nice 50/60 Hz flicker. The fix is to make very sure that there are no single lines in the image you're viewing. And, to make things worse, it's not as simple as just doubling the lines; you must double the correct lines, or they will still flicker in a marginally less obnoxious way; by seemingly jumping one pixel up and down. I'm illustrating this with a modified version of your test image, available at http://sam.kfib.org/p_img/seq0frame0001.png > and create a 1000 frame video from it. Bother. :) /Sam ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
