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-   -   SansGrip Filters: Sampler with bob issue (http://www.digitalfaq.com/archives/avisynth/2592-sansgrip-filters-sampler.html)

Fiz 02-13-2003 03:48 AM

Sampler with bob issue
 
Not sure if anyone else has had this. I have a pure interlaced 29.97 fps movie. I was trying different deinterlace filers to see which gave the best results for kvcd3 resolution 528x480.

I tried FieldDeInterlace, Bob and TomsMoComp filters to do comparisons. The sample was supposed to be 2m 20s for this movie but when I use Bob to deinterlace the sample becomes 1m 10s :? The movie does not seem to look sped up but Sampler is clearly taking half the frames for each segment of the movie.

The other deinterlace filters don't seem to have a problem. I am calling the deinterlace filter just after the Mpeg2Source line in my avs script and Sampler at the end. This also happens if there are no other filters in between.

I ended up using a res of 352x240 for this rip which deinterlaces naturally but was just curious to see if anyone else has had this problem.

urban tec 02-13-2003 07:20 AM

Yep, I was wonder why I was getting such good compression with my samples until I did the final encode and the file was twice the size it should have been.

muaddib 02-13-2003 06:04 PM

That's from AviSynch docs: :wink:

Bob takes a clip and bob-deinterlaces it. This means that it enlarges each field into its own frame by interpolating between the lines. The top fields are nudged up a little bit compared with the bottom fields, so the picture will not actually appear to bob up and down. However, it will appear to "shimmer" in stationary scenes because the interpolation doesn't really reconstruct the other field very accurately.

This filter uses BicubicResize to do its dirty work. You can tweak the values of b and c (see BicubicResize). You can also take the opportunity to change the vertical resolution with the height parameter.

Fiz 02-14-2003 03:39 AM

Thanks muaddib :) . Still curious though to why Bob would halve the number of total frames in Sampler :?

rendalunit 02-14-2003 04:25 PM

it might have something to do with the fact that bob() doubles the framerate :?:

muaddib 02-14-2003 06:17 PM

That's strange, cause it should double the frames... :roll: :?:
Well, at least if you fixed the length like this: Sampler(length=24)
Is that the way you are using it?

Fiz 02-16-2003 05:00 PM

Quote:

Originally Posted by muaddib
Well, at least if you fixed the length like this: Sampler(length=24)
Is that the way you are using it?

yup, sure is! And I agree, it should double the frames, but for some reason it seems to be halving them!

btw it's not such a big issue, was just being my curious self :roll: I like to know why things "happen" the way they do!

rendalunit 02-16-2003 05:12 PM

I wonder if it would work right if you doubled the # samples

bob()
sampler(samples=movietimeinminutes*2, length=24)

muaddib 02-16-2003 11:42 PM

Quote:

Originally Posted by Fiz
I like to know why things "happen" the way they do!

I always keep saying that! :D

If you find the answer... please tell us! :wink:

kwag 02-16-2003 11:48 PM

Quote:

Originally Posted by Fiz
I like to know why things "happen" the way they do!

Because Murphy is alive :mrgreen:

Fiz 02-17-2003 06:13 AM

Quote:

Originally Posted by kwag
Because Murphy is alive

lol! :mrgreen:


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