Path: utzoo!attcan!uunet!cs.utexas.edu!csd4.milw.wisc.edu!lll-winken!ames!sun-barr!newstop!sun!vector!poynton From: poynton@vector.Sun.COM (Charles A. Poynton) Newsgroups: sci.electronics Subject: Re: Converting PAL to NTSC on the fly Summary: Flicker, twitter, judder indeed. Message-ID: <120927@sun.Eng.Sun.COM> Date: 11 Aug 89 07:18:36 GMT References: <15315@pasteur.Berkeley.EDU> <10350003@otter.hpl.hp.com> <893@corpane.UUCP> Sender: news@sun.Eng.Sun.COM Reply-To: poynton@sun.com (Charles A. Poynton) Organization: Sun Microsystems, Mountain View Lines: 29 John Sparks writes: > Interlacing does not reduce flickering, it increases it. Television egineers have precise terminology for this otherwise confusing topic. Interlace improves wide-area FLICKER for a given frame rate, such as 29.97 Hz, over a non-interlaced sytstem of the same frame rate. However, this improvement comes at the expense of introducing inter-line TWITTER. Of course motion rendition is implicated in selection of a frame rate, and depends on interlace as well. Poor motion rendition can lead to JUDDER. > The even lines are sent in one frame and the odd in the next. No, the even lines are sent in one FIELD and the odd in the next. An odd field and an even field comprise a FRAME. > As far as we know, our computer has never had an undetected error. As far as we know, As far as we know, As far as we know, As far as we know, C. ----- Charles A. Poynton Sun Microsystems Inc. 2550 Garcia Avenue, MS 8-04 415-336-7846 Mountain View, CA 94043 -----