Decimating a 'progressive' NTSC DVD

[beerbohm]

Hi, I've had this problem a few times:

I've been trying to convert an NTSC DVD to AVI using DGIndex and Avisynth. The film itself has an original framerate of 24fps. However, instead of the usual telecined patterns, the DVD simply contains 1 dupe in every 5 frames. There is no combing whatever and the pattern is consistent throughout the stream. DGIndex recognises the stream as 100% progressive and when I try to decimate it using Avisynth, I come up against a brick wall: no frames are removed and the framerate stays the same at 29.976 fps.

Is this a common problem? I'm assuming that the d2v file is over-riding the avs command. Is there a way around this? Any help would be appreciated.

Here are the relevant parts of the avs script I've been using:

LoadPlugin("C:\PROGRA~1\AutoGK\DGMPGDec\DGDecode.dll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\decomb.dll" )

movie = mpeg2source("C:\...\DVD.d2v")
Decimate(movie,mode=0)

Thanks in advance for your help.

[manono]

mpeg2source("C:\...\DVD.d2v")
Decimate()

This assumes you made the D2V using 'Honor Pulldown Flags'.

Even your original script works, though, what you showed us of it, so something else is screwing it up. What's the full script?

[beerbohm]

Here is the full script:


LoadPlugin("C:\PROGRA~1\AutoGK\DGMPGDec\DGDecode.dll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\autocrop.dl l")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\decomb.dll" )

movie = mpeg2source("C:\...\DVD.d2v")
cropclip = autocrop(movie,mode=0,wmultof=4,hmultof=4,samples= 10,aspect=0,threshold=34,samplestartframe=0,leftad d=0,rightadd=0,topadd=0,bottomadd=0)
fixed_aspect = 0.888888888888889
c_width = width(cropclip)
c_height = round(height(cropclip) / fixed_aspect)
input_par = float(c_width)/float(c_height)
input_par = (input_par > 1.4) || (input_par < 1.25) ? input_par : (4.0/3.0)
out_width = 640
out_height = round(float(out_width) / input_par)
hmod = out_height - (floor(out_height / 16 ) * 16)
out_height = (hmod > 4) ? (out_height + (16 - hmod)) : (out_height - hmod)
new_aspect = (float(out_width) / float(out_height)) / fixed_aspect
Decimate(movie,mode=0)
autocrop(movie,mode=0,wmultof=4,hmultof=4,samples= 10,aspect=new_aspect,threshold=34,samplestartframe =0,leftadd=0,rightadd=0,topadd=0,bottomadd=0)
LanczosResize(out_width,out_height)

[manono]

If you're not actually using AutoGK, why use the scripts it generates?

Have you tried that script you showed earlier, leaving out all the other stuff. I did and got 23.976fps as expected.

I don't see how the rest of the stuff might prevent the decimation, but AutoGK has to use all that autocrop mumbo-jumbo, while 'normal' people don't. Do you know how to crop and resize on your own? That's what most of the script is all about.

[beerbohm]

I just tried the original script with everything else eliminated and the framerate comes out exactly right (23.976fps).

I don't know how to crop or resize on my own, so rely on the generic AutoGK script. I always have. Never imagined it would cause a problem like this.

This is encouraging. The main thing I need to sort out now is the resizing; then I'll let you know if it still comes out right.

Thanks for the help.

[beerbohm]

UPDATE:

This gives me the exact result I want:

LoadPlugin("C:\PROGRA~1\AutoGK\DGMPGDec\DGDecode.dll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\decomb.dll" )

movie = mpeg2source("C:\...\DVD.d2v")
Decimate(movie,mode=0)
LanczosResize(640,480)

Cropping isn't necessary as I want to keep the 4/3 aspect without losing any detail from the top and bottom.

I'm still not sure what caused the original problem but I was obviously over-complicating things. Thanks again for your help.

[Gavino]

I'm still not sure what caused the original problem but I was obviously over-complicating things.

Here is the full script:
...
movie = mpeg2source("C:\...\DVD.d2v")
...
Decimate(movie,mode=0)
autocrop(movie,mode=0, ...)
LanczosResize(out_width,out_height)

You applied autocrop to the original ('movie') instead of to the result of Decimate (which then gets ignored).

You should have written either

movie = Decimate(movie,mode=0)
autocrop(movie, mode=0, ...)

or

Decimate(movie,mode=0)
autocrop(mode=0, ...) # using implicit 'last' as input

[manono]

Thanks Gavino. I should have been able to spot that. But I didn't.

I don't know how to crop or resize on my own, so rely on the generic AutoGK script.

Do you have Gordian Knot installed? If so, you can do an easy crop and resize in it.

Open the DGIndex generated D2V in GKnot and go to the Resolution Tab. Make sure the correct Input PAR is already ticked (4:3 or 16:9). Start cropping the picture using the Pixel Crop. Move the slider to get the width you want (640 in this case, I guess) and after the cropping and resizing is done, above the video picture go File->Save And Encode->Edit and grab the crop and resize lines from the GKnot generated script. You might even want to begin using it as your 'template' because it's more understandable than is the AutoGK one. Remove all the lines beginning with '#' since they don't do anything.

Oh, in the Options Tab I check the 'Follow ITU...' box.