Vidiot (brown@xxxxxxxxxxxxxxxxxx): > > It is the only TV app that I know of under linux that deinterlaces > > to field rate. > > Why would you want to deinterlace NTSC, or PAL, video? If the idea is > to capture, edit and burn a DVD, or even send back out the firewire to > tape, the last thing you want to do is screw up the video by > attempting to deinterlace it. The purpose is for watching it. tvtime is a realtime deinterlacer, and is not intended for recording. The deinterlacing filters are optimized for best quality for realtime performance, not high quality for recompression. Obviously, if you are burning a DVD, you should record the interlaced stream and encode to interlaced MPEG2 (unless it is film material as you mention next). There are two reasons to deinterlace. If your monitor's refresh rate is genlocked to the input, then deinterlacing is simple. Linear interpolation looks identical to a real television or high quality studio monitor, and a higher order interpolator or motion adaptive interpolator can get rid of some of the spacial artifacts. Excellent stuff. So, one reason to deinterlace is simply to stabilize the picture, that is, try and do a better interpolation of each field to a full frame for added spacial resolution. However, in the PC world we have a problem. I have found it a challenging problem to software genlock a computer monitor to the video input, although some progress is being made. Also, many data projectors, the refresh rates they provide are limiting. Because of this, you see temporal aliasing as the 59.94fps content of NTSC video conflicts with the 75hz or 85hz refresh of the display. This aliasing appears as bouncing artifacts, as the eye shifts between a sequence biased towards top fields to one biased towards bottom fields. Using a motion adaptive interpolator removes this effect and can regain quality, but there's nothing to be done about some of the judder that results besides finding the best amortization of 60fps content on an 85hz refresh. tvtime attempts to achieve this. > Even if you want to attempt to inverse telecine film that was > transferred to NTSC, you still do not want to deinterlace it first. > Let the inverse telecine software do its job on the real NTSC > interlaced file, as it will have a better chance of determining the > pulldown pattern. We can do pulldown detection, in realtime, and it operates on the interlaced content. > As far as I am concerned, deinterlacing reduces vertical resolution. > I've yet to find a use for it. Only if you do something like deinterlace 59.94fps content to 29.97fps, as most 'deinterlacer' filters do. -- Billy Biggs vektor@xxxxxxxxxxxx
