joe briggs (jbriggs@xxxxxxxxxxxx): > Isn't this standard conversion a hardware process? Being able to output a composite NTSC signal, a VGA signal, or a PAL signal is a hardware process handled by the video card. However, software still needs to provide the images to display. > For example, you have long been able to buy analog standard converters > from RadioShack, and you have certainly been able to purchase digital > standard convertser which frame grab in one standard, and clock out in > another - these are used by tv stations and tape conversion houses. There are many poor methods of framerate conversion. See my repost where I describe one way of using 50-50 image blurring to deal with motion. Other converters screw motion. I see some really strange artifacts sometimes when watching PAL-recorded material broadcast here, and often the motion is just messed up. Do a search on 'pal ntsc conversion' for more discussion. There's also a really great article on it that I found once and I'll try to find again... > However, many "book pc's" - these small footprint PC's, usually a i810 > chipset, have both VGA and composite/s-video output as well. In the > bios setting for these, you have the option of selecting the TV video > mode to PAL/NTSC/SECAM. Even if you are running Linux and set X to > 640x480, it looks great on the TV out. Watching low-framerate material, like using your desktop or watching a 24fps video, looks fine on displays at 50hz (PAL TV), 59.94hz (NTSC TV), and a VGA monitor (50hz+). Watching 25fps or 29.97fps material on an NTSC TV is also pretty safe, you'll likely only see a stutter every 30 seconds or so depending on how different your clocks are. But watching true 50fps or 59.94fps material on any of these displays, you start to get into trouble. Remember, when you watch a PAL TV, you're watching 50 images per second, and with NTSC TVs, it's 59.94 images per second. Recording at half rate like 25fps or 29.97fps you're already protecting yourself against framerate judder. -- Billy Biggs vektor@xxxxxxxxxxxx
