Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.


Go Back   Doom9's Forum > Capturing and Editing Video > Avisynth Usage

Thread Tools Search this Thread Display Modes
Old 25th August 2008, 04:33   #121  |  Link
*.mp4 guy
Registered User
*.mp4 guy's Avatar
Join Date: Feb 2004
Posts: 1,350
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.
*.mp4 guy is offline   Reply With Quote
Old 25th August 2008, 06:27   #122  |  Link
Resize Abuser
mikeytown2's Avatar
Join Date: Apr 2005
Location: Seattle, WA
Posts: 623
@*.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/
mikeytown2 is offline   Reply With Quote
Old 25th August 2008, 21:09   #123  |  Link
*.mp4 guy
Registered User
*.mp4 guy's Avatar
Join Date: Feb 2004
Posts: 1,350
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.
*.mp4 guy is offline   Reply With Quote
Old 30th August 2008, 05:20   #124  |  Link
Registered User
Join Date: Jul 2006
Posts: 118
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:

Global NewHeight = 480
Global NewWidth  = 720

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

# Pick one manually, DirectShow has no idea


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
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?
Florin Andrei

florinandrei is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +1. The time now is 12:13.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.