AviSynth Order of Operations

[Gramps]

Hi,

I've used Avisynth for a number of years. Great tool that lets you perform all sorts of stuff with video in an almost infinite number of ways. I'm far from being an expert with it, but I can generally get it to do what I want with it through trial and error.

Anyway, I was wondering if the Avisynth gurus here could offer any kind of rule of thumb guidelines as to the order of operations when cleaning up and enhancing video for playback on a PC or via streaming media player. I don't burn to DVD anymore. I generally prefer having progressive video rather than interlaced. The approach that I generally take and the order I do it in is as follows:

- Specify the source file
- Deinterlace if needed
- Deblock it
- Do the cleanup activities (noise removal/halo removal/smoothing/etc)
- Color/ levels/hue/contrast/sat correction
- Resizing or Aspect Ratio changes
- Framerate adjustment
- Sharpening

Of course, most of these steps are optional as it all depends on the individual video.

Just curious if that is the correct order that such activities should be performed when restoring video, or is a different order more effective, and why?

[sanlyn]

- Specify the source file
- Deinterlace if needed
- Deblock it
- Do the cleanup activities (noise removal/halo removal/smoothing/etc)
- Color/ levels/hue/contrast/sat correction
- Resizing or Aspect Ratio changes
- Framerate adjustment
- Sharpening

Of course, most of these steps are optional as it all depends on the individual video.

Just curious if that is the correct order that such activities should be performed when restoring video, or is a different order more effective, and why?

This is all up for grabs, of course.

1 - Specify the source file
2 - Basic levels/valid chroma range correction (tweak later)
3 - Deinterlace\inverse telecine, if needed
4 - cleanup (noise removal/halo removal/smoothing/etc)
5 - Resizing or Aspect Ratio changes
6 - Sharpening, if needed
7 - Re-interlace if needed
8 - Framerate adjustment
9 - Tweak for Color grading/black levels/white balance/sat, etc.
10- Encoding / final output

Step 2: Adjust luma/chroma within valid ranges for the intended output and colorspace. "Color balance" isn't the issue at this point, but clipped/crushed values will affect all later processing. The better deinterlacers and denoisers use masking, motion interpolatioon, resizing, inter-pixel analysis, etc.. Most of them can't deal with below-black or greater-than-white values very well.

Step 9: Previous processing will affect color and contrast. Analog sources/VHS need color and level adjustments almost down to a scene-by-scene level. The girl with blonde hair in scene 7 should not be a redhead in scene 25 and then a brunette brownie in scene 40. A man entering a scene in a dark gray suit should not be wearing dark green in the next shot. Silver-gray hair should not have purple shadows. Special effects or lighting changes aside, if a room has white walls when a scene begins, the walls shouldn't be orange when the scene ends. Facial highlights shouldn't look yellow. Most digital sources are easier for obtaining consistent color balance for the length of the video.

[Gramps]

Thanks, Sanlyn!

[2Bdecided]

Like Sanlyn, I try to get the levels approximately right early on - especially before denoising - it avoids banding.

If you ever need to remove dot crawl, you'll need to do that as step 2.

Otherwise, yes, same here.

Cheers,
David.

[sanlyn]

Right, 2B, thanks for adding that about banding.
I hate banding. Crushed colors just make it worse.

[Gramps]

Is there a reason that you do sharpening prior to color adjustments? I assume it is just so you can do the color corrections via VirtualDub, but let Avisynth do the sharpening, correct?

[sanlyn]

Exactly when sharpening occurs depends on whether the video is interlaced or not. I avoid sharpening interlaced video. If I can't, I often use SeparateFields() first. The reason for tweaking color/contrast later is that sharpening affects contrast.

That workflow isn't hard and fast 100%. Some video has problems that require schedule changes, but what I posted is what I do most of the time. My favorite sharpener is Neatvideo (usually with its other filter settings turned almost down to nothing, if not altogether off), as it also lets you sharpen luma, one or both color channels (it works in YCbCr), or all three. But in Avisynth I usually go with LSFMod. There are many alternatives, depending on the problems.

[Gramps]

Gotcha. Thanks for the tip.

[ConverterCrazy]

Hi all,

The Video Converter from iSky (Trial version) allows A/R and size adjustment/correction with least efforts. The Edit option takes user to the next screen and adjustment can be made with mouse.

Is this feature available in any free Converter tool?

[sanlyn]

Hi all,

The Video Converter from iSky (Trial version) allows A/R and size adjustment/correction with least efforts. The Edit option takes user to the next screen and adjustment can be made with mouse.

Is this feature available in any free Converter tool?

The question has nothing to do with this thread, but you can check on tons of convberter programs (free and not-free) in the videohelp tools area: https://www.videohelp.com/tools

[ConverterCrazy]

Thanks, sanlyn.

Sorry about the wrong thread. I request the Moderator to move my post to appropriate thread

I have many of them converters and used them. I didn't see this feature; hence, I thought some member may be aware of any such converter/editor.

Thanks.

[sanlyn]

No problem, C-Crazy, happens all the time. Meanwhile I had to change "convberter" in my post to read "converter". At least you can type.