Quote:
Originally Posted by IanB
Effectively all the pixels in the new fields are vertically blurred slightly.
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Yes, demonstrably true,
but...
1. You will then resize vertically to less than half the original resolution (or a little more than half the original resolution for "PAL") - that's a fair amount of blur!
2. You will then throw away half the remaining lines in each field to interlace the signal - that's a fair amount of lost information.
3. You will then rely on the deinterlacing in the display, if any, to restore those missing lines - or view on a native interlaced display, which will display inter-line twitter on sharp vertical details unless they are blurred before interlacing! Either way, you will be very lucky to see any extra detail you recovered with a "smart" bob.
As for "why not use X smart bobber - it's still fast?" – fast, yes, but everyone one I've seen (that counts as "fast") is prone to artefacts on something - sometimes quite nasty artefacts. The artefacts can be far more visible on the downconversion than any slight softness due to bobbing.
Of course mcbob to tgmc will do a better job and are almost always artefact free - but with these the slow down is considerable.
Cheers,
David.