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H264 for iPod may be larger than 320 pixels wide
Authored by: stephanos on Jan 19, '06 07:47:12AM

Formula for calculating video size:

x=sqrt(76800*r)
y=x/r

Where r is the aspect ratio (e.g. for 16:9 it's 16/9), x is the pixel width and y is the pixel height. If you round down to integers, for 16:9 video it comes out to 369x207 = 76383 pixels, though 370x207 and 369x208 also come out to less than 76800.

This is where I recommend the excellent FormulaCalc widget - the only Dashboard calculator you'll ever need.

As to what that looks like on an HD screen, I'll leave that for someone who can afford the hardware to find out :-)



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FormulaCalc Issues
Authored by: richardab on Jan 19, '06 09:48:24AM

I just downloaded FormulaCalc from the German website. But how do you do the square root? I tried X^(1/2) but that only yielded X. In fact how do you do exponents? Because 9^2 yields 11 not 81. It seems like a nice widget but not very powerful if it can't do exponents. Maybe I'm just using old school notation or they use different symbols in Germany.



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H264 for iPod may be larger than 320 pixels wide
Authored by: lstewart on Jan 19, '06 09:51:24AM

Obviously video at this size will have to be scaled to play back on the iPod itself. And while the iPod is capable of this video scaling, some people have reported smoother playback of scaled videos when the resolution is evenly divisible by 16. While the original poster's 2.35:1 aspect ratio suggestion of 416x176 fits this suggestion, the formula suggested here does not.

My question is: I think I read about the divisible-by-16 rule as it was being applied to MPEG4 video. Can anyone confirm whether it applies to H.264 as well? Will odd-pixel-sized H.264 scale smoothly for playback on the iPod? (Or are there flashing/flickering/choppy artifacts during playback?)



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