Avisynth script suggestions

[pijetro]

I'm just starting to learn this great program (thnx rob1). I've noticed that filters can give you bad results after being ordered incorrectly, (ie resizing).
Is this script economical for my encoder?? I'm looking for better speed, and was hoping that somehow the separatefields() command would improve it
I'm serving to CCE, and the speed is only .38 on a P3 1ghz 512ram system. I'm trying to improve it. Does filtering within separated fields help for better quality??

loadplugin("e:\avisynth2\plugins\dnr2.dll")
AviSource("f:\Boki 8mnth.avi")
clip1=trim(0,28895)
clip2=trim(28896,33806).tweak(bright=65,cont=.9) #extremely dark VhsC source
clip3=trim(33807,45039)
clip4=trim(45040,55446).tweak(bright=60,cont=.9)
separatefields()
crop(0,4,-0,-10)
dnr2()
weave()
clip1++clip2++clip3++clip4
LetterBox(7,7)
lanczosresize(720,480)

Is there somewhere central that I can find what the filter values are for various spatialsofteners and noise reducers?? Like an AVIsynth For Dummies website??? The values seem confusing, especially when I don't understand the syntax that's presented

Thanxxxx

[kees1952]

Just my thoughts.
You use the tweak() function to enhance brightness and decrease contrast. Consider the use of the gamma function in levels(). This has the advantage that the black and white levels stay on the value you've adjusted during capturing.
Separatefields() deinterlaces and weave() interlaces again. Is this necessary?
Lanczosresize() resizes to the final format. If possible try to capture in this format so resizing functions are not necessary. All resizing functions give an unsharp picture more or less. Try to avoid them.
For filter values on softeners and noise reducers, experiment with them, try to overdue to see the effects.
As your final size of the avi will be 720x480. i assume you're working with DVD video. Filter as little as possible, DVD has enough bandwith to produce clean/nice video mpg's of you're VHS-C tapes, without blocking efects.
Regards, Kees Janssen.

[pijetro]

I use bright and contrast, because of its ease of use. I'm not familiar with the values or functions in gamma.
I separate fields, assuming that it's faster for the encoder to calculate and that dnr2()on a separated field will clean up more thouroughly.
I capture in 720x480, but unfortunately the VHSc tapes have garble on the bottom, thus the cropping and letterboxing.
Perhaps I should addborders rather than letterbox and resize. Thanks for the suggestion.

As for softeners and noise reducers, what do you suggest for 1)hard noise from sattelite broadcast, and 2)small artifacts on peoples faces.
I would be grateful if I new what those values meant. Like I said earlier, I don't understand the syntax on the guides, so the values don't mean anything to me.

Thanx......

[kees1952]

Use VirtualDub to experiment with the gamma correction in the levels function (video, filters, add, levels). It has a preview so you can see the result.
All VHS tapes give garbage at the bottom, it's the point where the 2 or 4 videoheads will have to synchronise again. It's common practise to crop this lines off but two rules: try to avoid changing of your resolution (720x480) and crop in multiples of 8, the MPEG encoders like this better.
For you: crop(0,4,-0,-12) and addborders(0,8,0,8) and you'll end up with a centered image of 720x480. No resizing necessary. Due to the overscan on a TV set you will not notice the black borders)
For softeners and noise reducers:
Spatialsoften(radius,luma threshold, chroma threshold)
SpatialSoften replaces each sample in a frame with the average of all nearby samples with differ from the central sample by no more than a certain threshold value. "Nearby" means no more than radius pixels away in the x and y directions. The threshold used is luma_threshold for the Y (intensity) samples, and chroma_threshold for the U and V (color) samples.
TemporalSoften(radius,luma threshold, chroma threshold)
TemporalSoften is similar, except that it looks at the same pixel in nearby frames, instead of nearby pixels in the same frame. All frames no more than radius away are examined. This filter doesn't seem to be as effective as SpatialSoften.
I cannot judge the "hard noise" of a sattelite broadcast, but for my VHS captures i use something like:

Spatialsoften(2,10,40)
Temporalsoften(1,8,40)

Just some values for you to start with. Experiment with them, encode a small piece of the avi to mpg with several settings and watch the results on your TV.

Good luck, Kees Janssen.

[DJRumpy]

Rather than cropping, you should use the letterbox function. It will simply 'black' out the border. This avoids a resize, and a potential loss in quality.

[pijetro]

Thanx alot kees1952. Simple English is what i like to read..Great suggestions.
DJRumpy, I tried a letterboxing and crop, but felt comforatable with crop, because it ensured that the encoder isn't gonna have to waste bitrates. I was under the impression that letterboxing just overlayed, and didn't truly cut out the potentially wasted bitrates.

To answer my own question about speed. I reencoded, and noticed a drop in encoding speed from .405 to .38 when I opted not to separate the fields. Does this altogether seem slow on a P111 1ghz/AsusCuslc-2 motherboard??

[kees1952]

You're Welcome.
To be clear: crop() + addborders() cut and add lines.
letterbox() overlays with black (default) borders. Letterbox() is a combination of crop() and addborders(). But by using the last you can end up with an vertical centered image (if you want).
As for the encoding speed: for me it's second place, quality is first. I do my encoding in batch at night or when i'm at work so it's no issue for me. I cann't judge wether it's fast or slow on your system. Computers get faster every month and yes, within a few years we will be encoding at half the time we're using now. But what we're doing at this moment is what counts for me.
Regards, Kees Janssen.

[DJRumpy]

Letterbox can be duplicated with Crop, and AddBorders, but it's not as fast. Don't worry, it completely blacks the image where specified, so no bitrate will be wasted. It's also faster than using the Crop and AddBorders combo. This is the command you should use when you want to avoid resizing, or you just want to remove edge noise.