You've got it backwards. Interlace runs at 60fps, progressive runs at 30 (or 24) fps. You're right it's not technically 540p, but in 1080i there are only 540 lines displayed at any given time (hence the double frame rate, which is required to deliver the two half-images at 30fps),. Also keep in mind that your HDTV is not natively capable of displaying interlaced video (interlace only works natively with CRT displays). If fed interlaced video it has to run it through a deinterlacer, which degrades the video, since one interlaced frame is actually comprised of two half frames shot at different moments in time. If you were to simply combine two consecutive interlaced half frames into a 1080 line still image and look at it there would be motion blur (combing) on anything that is moving. So the deinterlacer has to 'interpolate' (fake by guessing) the other half of the information that it thinks should be part of each progressive frame.
1080i upconverted to 1080p will never look as good as something shot and displayed in 720p. It's actually a bit smoother to downconvert to 720p from 1080i because there's a lot less missing information that the deinterlacer has to interpolate to make each progressive frame.
1080i upconverted to 1080p will never look as good as something shot and displayed in 720p. It's actually a bit smoother to downconvert to 720p from 1080i because there's a lot less missing information that the deinterlacer has to interpolate to make each progressive frame.
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