Interlace, let's talk about it.......
I know what interlace is and why it exists but I'm confused about how it operates between different hardware and software.
I'm working on my never ending home movies restoration job. All my VHS tapes are caped in HUFFYUV
720x480i. So the files look more or less identical to the original VHS except the rescale. Now when I play the HUFFY files back in, say, VLC and choose the de-interlace option, it does a fairly good job on playback. Also AVISynth does a good job of de-interlaceing.
But... if I want to leave the video interlaced, how does software and hardware understand how to de-interlace video? I derailed my logic when I realized that 720 is a higher resolution than the original VHS frames, therefore I have effectively doubled up on some pixels. How in the world does my playback system know which pixels belong to which fields? If I place a black mat over my frame or resize the footage and encode is to MPEG2 and burn it to DVD, do I get some weird multiple interlace? How does anything in the encode/playback chain keep track of "fields" when footage has been re-scaled?