Determining correct order in AVISynth Script?

[Killer3737]

I've used AVISynth for quite some time now but I've never really delved deep into it and understood everything it does, rather finding other peoples scripts and modifying them for my needs.

I know what most of the fuctions I use do (Mainly MPEG2 conversions of some sort) but what I don't know is the correct order items should be in? Is there a correct way, will it affect things greatly in the wrong order? For example, I butchered this script together:

mpeg2source("E:\Foo.track_4113.d2v")
Load_Stdcall_Plugin("E:\Random\MeGUI\tools\yadif\yadif.dll")
Yadif(mode=1)
Spline64Resize(720,576) # Spline64 (Sharp)
ColorMatrix(mode="Rec.709->Rec.601")
DeGrainMedian(limitY=5,limitUV=5,mode=3)
SeparateFields()
SelectEvery(4,0,3)
Weave()
ConvertToYV12(Interlaced=True)

Now I know what it's doing there, basically de-interlacing, resizing, applying a color mode change and a slight degrain before re-interlacing and converting to YV12 but is that in the right order? Should the degrain and colormatrix come after the re-interlacing? I don't know. I've seen people say to test your avs file in VirtualDubMod but how? I can open the file but then what? A bit of help understanding the logic of ordering AVISynth files would be great.

[AlanHK]

Resize and sharpen will both make noise worse and harder to filter.

So as a general rule, you should do de-noising (eg, DeGrainMedian) before resizing (Spline64Resize), and definitely before sharpening (Spline64Resize again). And also before any colour changes : basically, clean first then enhance.

I think better:

mpeg2source("E:\Foo.track_4113.d2v")
DeGrainMedian(limitY=5,limitUV=5,mode=3)
Yadif(mode=1)
Spline64Resize(720,576) # Spline64 (Sharp)
ColorMatrix(mode="Rec.709->Rec.601")
SeparateFields()
SelectEvery(4,0,3)
Weave()
ConvertToYV12(Interlaced=True)

Just being able to open a file in VirtualDub tells you that it the script is valid.
I do like VirtualDubMod, which has a simple AVS script editor built in.
You can do F5 or F7 to reload and play.

But much more powerful is AvsPmod. You can click to duplicate a script to a different tab and them modify and compare. And it creates sliders for most parameters. Only can't "play" (though it can launch a player).

Also if you put your plugins in the Avisynth plugins folder, they will be automatically loaded and you don't need to do that in the script, so I omitted that.

[Gavino]

Also if you put your plugins in the Avisynth plugins folder, they will be automatically loaded and you don't need to do that in the script, so I omitted that.

But Yadif is not a standard plugin and requires to be loaded using Load_Stdcall_Plugin (or LoadCPlugin).

[jagabo]

I've never used DegrainMedian()

mpeg2source("E:\Foo.track_4113.d2v")
DeGrainMedian(limitY=5,limitUV=5,mode=3)
Yadif(mode=1)
...

but don't you need to specify interlaced=true if you run it on interlaced video?

[Killer3737]

I've never used DegrainMedian()

mpeg2source("E:\Foo.track_4113.d2v")
DeGrainMedian(limitY=5,limitUV=5,mode=3)
Yadif(mode=1)
...

but don't you need to specify interlaced=true if you run it on interlaced video?

Just checked back on the release page and yep I missed that, thanks for pointing it out. I've never used it before either, my reason for it was the source video looking like this - http://www.mediafire.com/?54upty666x6f8y7 at times. Is that the right filter choice to try and tone that down a bit or is there a better alternative?

[jagabo]

I think using DegrainMedian() after Yadif() would work better (though more time consuming). In which case you don't need the interlaced=true flag.

[Killer3737]

Ok thanks.

Are there any other general script rules regarding ordering?