On Tue, 22 Jan 2002, Billy Biggs wrote: > For a good overview see: > http://www.microsoft.com/hwdev/archive/TVBROADCAST/TempRate.asp I read and really enjoyed this article. It does open your mind to the subtleties of "moving image" reproduction. One thing I hadn't really absorbed before is that with video material, not only do the two fields represent two distinct points in time, but even within one field the pixels are sampled sequentially in time. IE - if you have a field in 50Hz field rate video, the first sample of the first line of the first field was sampled from the original scene at time 0ms, the last sample of the last line of the first field was sampled from the original scene at time +/- 17.43ms For film material, on the other hand, each film frame does represent a single point in time (well - nearly; each frame actually integrates the original scene image over a period of about 20ms). So - it is correct to show the whole frame at once. All this has very subtle implications when you are trying to achieve highest fidelity reproduction of the original scene in temporal terms. My application is fairly simple because my output is a TV, which is the "expected" output device for the vast majority of video material. But solving this where the video material and the display device have different, "non-integral-related" sample rates looks quite tricky... Steve
