Are filters necessary?

[plissken]

As far as I can tell there are no filters active when I encode. I don't turn on any noise filter. I just use Gordian Knot's default settings. Do the default settings include any filters?

If there are, then I might be able to speed up my encoding time if I turn them off. Which begs the next question, do they offer any worthwhile improvement if I encode at 640 by xxx (or higher resolutions) with file sizes around 1G and Lanczos resizing?

[chemmajik]

It all goes back to how the quality of the source is, bad vcr tapes or low quality cameras sometime just really need it, but in most cases NO... Every filter you use will cause a fine detail loss, and can produce to much of a smoothing effect.

[jggimi]

@plisken:

You can tell what filters are in use by examining the AviSynth script (.avs file) produced by Gknot. Lines beginning with the "#" character are comments and ignored by AviSynth. You can edit these files from the Save & Encode window.

At minimum, using Gknot for DVD, you will have the following filters:

mpeg2dec3 or variant -- used for frameserving video from VOBs (.d2v project)
cropping
resizing

Other filters will depend upon choices you make in the Save & Encode window.

[OvERaCiD23]

I see from your signature you do 2 CD rips with only 160kps audio. You shouldn't ever need to use noise filters, as you should have MORE than enough bits on every encode you do to not need noise filters (unless the movie is noisy, long, etc). 1 CD rips will often require heavy filtering; 2 CD rips can sometimes, especially when including the original AC3 track (in most of my cases). These cases usually require very light filtering, such as Convolution3d(preset="movieHQ"), or FluxSmooth. It all personal preference when it comes to filters; if it looks good to you, that's all that matters.

[manono]

Hi-

...such as Convolution3d(preset="movieHQ"), or FluxSmooth.

He said he wants to speed up the encoding, not slow it down. :) As jggimi said, you're already using filters. If speed is your only consideration, use another resizer besides LanczosResize. Not that I'm recommending that.

do they offer any worthwhile improvement...

I agree with OvERaCiD23 that in the case of noisy movies they can aid in the compressibility of the movie, and improve its looks. But some people don't believe in them at all (Doom9). Test and decide for yourself.

However, in your sig you mentioned using FieldDeinterlace. Do you do that every time? And for what possible reason? There's your bottleneck. If you're encoding from DVD movies, about 99% of the time you won't need it, and using it will only slow you down and degrade your encode.