Converting 30fps Progressive to 25fps interlaced ? (Avisynth & VDub)

[blewyn]

I have been unable to convert my PAL video to 30fps progressive without unacceptable loss of quality (using VDub and smooth deinterlace then convertfps etc) so am now trying to convert my 30fps progressive to PAL video, in order to retain picture detail and fluidity. What's the best way to do this ?

So far I have tried :

Doubleweave()
Selectodd()
Convertfps(25)

Which is nice and fluid but looks a bit blurry. Is there a better way ?

[guns1inger]

You might want to take a look at this page, which is for an avisynth port of smooth deinterlacer written specifically for format conversion. Scripts to sho wit in use and discussion of why he has done things the way he has are at the bottom of the page

http://www.guthspot.se/video/AVSPorts/SmoothDeinterlacer/

[manono]

That page is for interlaced sources and output. It's all about 50fps to 59.94fps and vice versa. Of course, that's the way it should be done, starting with treating the 30fps progressive source as if it's interlaced

If you're willing to get an interlaced result it can be done reasonably well. Otherwise 30fps progressive to 25fps progressive is either blend everything together and make it play blurry or drop unique frames and make the result play jerky. It just can't be done well. Either that or slow the thing down, slow the audio, and have everyone move in slow motion and talk in deep voices. Or unless you want to use AviSynth's MVTools to create new frames and take forever to do it.

Here's xesdeeni's page on standards conversions:

http://www.geocities.com/xesdeeni2001/StandardsConversion-Preview-0.html#_From_29.97p_2

This is the script to use:

1. Without audio processing:

xxxSource(“30p.xxx”)
LanczosResize(width, height)
ConvertFPS(50)
SeparateFields()
SelectEvery(4, 0, 3)
Weave()

[jagabo]

I hate the kind of blending ConvertFPS() introduces. Anyone ever tried something like this:

AVISource("filename.avi")
AssumeTFF()
AssumeFPS(30) #instead of 29.97
LanczosResize(720, 576) #or whatever
ChangeFPS(60) #dup each frame
SeparateFields() #split into fields
SelectEvery(24, 0, 3, 4, 7, 10, 13, 14, 17, 18, 21) #pick 10 fields out of 24
Weave() #output 25 fps interlaced

I tried this on a true 29.97 fps progressive source and it looked pretty smooth, a bit like 3:2 judder with NTSC film. Note that the audio will get out of sync by about 1/10 of a percent.

I wonder if the OP's file is really 30 fps though. It might be 23.976 with duplicates to make 29.97. Or the result of a blend deinterlaced.

<later>

After thinking about this a bit, the above script can be optimized. Though it looks tricky:

AVISource("filename.avi")
AssumeTFF()
AssumeFPS(30) #instead of 29.97
LanczosResize(720, 576) #or whatever
SeparateFields()
SelectEvery(12, 0, 1, 2, 3, 4, 7, 6, 9, 8, 11) #pick 10 fields out of 12
Weave()

[blewyn]

It's 30p from a Pentax Z10 (X10 ?) digi camera.

I tried converting the PAL footage to 30fps and it looked OK, a little blurred in some frames but it was acceptable. I then appended a 30p sequence to it in the hope that media player classic and ffdshow would be able to deinterlace on the fly and render the whole without combing (ie interlaced and progressive 30fps in the same file) but it didn't work -the combing and ghosting was too visible.

I'll try your script, thanks.

[guns1inger]

It is also 640 x 480, I am guessing, so you may be losing something in the resize as well.

[blewyn]

Worked like a dream ! Far better detail and fluidity preservation that anything I achieved trying to convert 25i to 30p, the only noticeable difference between the converted 25i and the 30p original is a very slight shimmer in high-brightness areas, but really it's the kind of thing you wouldn't notice if you weren't looking for it.

Seems like this is the definitive 'best solution' I have so far found for combining 25i and 30p footage, in terms of visual quality.

Thanks !