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Old 25th August 2008, 04:33   #121  |  Link
*.mp4 guy
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It does lowpass between 120 and 240 lines, but because it is low ringing and has a low number of sample points (relatively speaking, you need more and more sample points the more frequencies you eliminate) it loses a lot of frequency amplitude all the way to around 60 lines. This filter is a simple chebyshev windowed sinc fir filter.


frequency response graphs:
The filter I posted
A bit more aggressive filter
non windowed sinc, with 2x the sample points

The line shows the aproximate location of the ideal cut off point, the boxes indicate manifestations of ringing.
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Old 25th August 2008, 06:27   #122  |  Link
mikeytown2
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@*.mp4 guy
would you mind explaining what software package you used to create the numbers/graphs?

My guess is http://octave.sourceforge.net/
found this graph with GNU Octave Code: http://en.wikipedia.org/wiki/Image:Phase_Plots.svg

web front end of Octave http://hara.mimuw.edu.pl/weboctave/
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Old 25th August 2008, 21:09   #123  |  Link
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In this case I used winfirdesigner which is a simple freeware fir filter design program that supplies some nice graphing functionality. I've never heard of Octave, but it looks interesting.
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Old 30th August 2008, 05:20   #124  |  Link
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I tested the convolution script posted by *.mp4 guy but it's very slow and it's very blurry. The vertical resolution is bad and the conversion speed is like 0.5 fps on a fast machine.

I tested the new corrected shift/interleave script:

Code:
Global NewHeight = 480
Global NewWidth  = 720

DirectShowSource("hd.m2ts", audio=false)

# Pick one manually, DirectShow has no idea
AssumeTFF()
#AssumeBFF()

SeparateFields()

Shift = (GetParity() ? -0.25 : 0.25) * (Height()/Float(NewHeight/2)-1.0)

E    = SelectEven() . Spline36Resize(NewWidth, NewHeight/2, 0,    Shift)
O    = SelectOdd()  . Spline36Resize(NewWidth, NewHeight/2, 0,   -Shift)
Echr = SelectEven() . Spline36Resize(NewWidth, NewHeight/2, 0,  2*Shift)
Ochr = SelectOdd()  . Spline36Resize(NewWidth, NewHeight/2, 0, -2*shift)

Interleave(E, O)
IsYV12() ? MergeChroma(Interleave(Echr, Ochr)) : Last
Weave()
Compared with the initial version (that didn't process chroma separately), this one looks very similar. I didn't do an A/B comparison, but viewing them successively I can't tell any difference.
The corrected version is a bit slower (10.3 fps vs 12.7 fps) but that's OK. This new script supposedly deals with chroma correctly, so I think I'll just use it.

Are we out of ideas yet?
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