Best option for resizing in AviSynth

[DRP]

I don't understand the logic of AviSynth scripting. I have a few saved scripts which I can edit to do various common tasks I need occasionally, but that's as far as I go usually. I want to resize some files I'm converting to DVD and would like to do it completely within AviSynth if I can rather than through VDub which I usually use for resizing.

1) What is the best quality resizer to use in AviSynth with nothing but quality in mind and that I like a sharp picture rather than a smooth one. I was thinking Lanczos4Resize but then I found this new one called Spline36Resize. There is a good description written about Lanczos4Resize but nothing for Spline36Resize. What are the pros and cons of using Spline36Resize?

2) When I've decided which resizer algorithm to use in 1) above, what would be the correct scripting to resize an input video of 464x352 to an output size of 408x576 letterboxed within a black frame measuring 544x576?

The reason is that I want the 4:3 ratio end video for display on a 16:9 screen which doesn't have a black background display option, so I'm including the black background on the disc instead so I'm not distracted by the light grey background of the screen in 4:3 display mode.

My DVD player has no dramas playing 544x576 video on DVD with a 16:9 display flag, so it works perfectly, I've tested it. Thanks.

[AlanHK]

I use FitCD to generate the code for resizing, saves hassle.

You can let it generate the whole AVS file or just copy and paste the relevant parts into your own script.

As for the merits of various resizers, the differences are minute, I think. I just use Lanczos.

AvsP is a really good editing tool for creating and playing with AVS scripts.

Takes a little while to get the hang of it, but if you're applying various filters and adjusting the parameters it's really the only way to go.

scripting to resize an input video of 464x352 to an output size of 408x576 letterboxed within a black frame measuring 544x576?

FitCD for source 464x352 and output 544x576
gives you :

LanczosResize(528,576,0,0,464,352)
AddBorders(8,0,8,0)

[manono]

Hi-
1) Did you read everything at the AviSynth.org Resize page, the link it gives in the Spline section, and the external link at the bottom of the page:

http://avisynth.org/mediawiki/Spline36Resize

2)LanczosResize(408,576).AddBorders(68,0,68,0)

[FulciLives]

I'm still using LanczosResize myself (old habits die hard) but I've heard that Lanczos4Resize is better. I've not heard of Spline36Resize and knowing the AviSynth experts it might have a very specific purpose so I would just stay with Lanczos if I were you.

As for your resize ... use FitCD to get the correct ratio.

Using your example of 464x352 with FitCD I get the following:

With ITU resizing:

LanczosResize(544,576,0,0,464,352)
AddBorders(88,0,88,0)

Without ITU resizing:

LanczosResize(528,576,0,0,464,352)
AddBorders(96,0,96,0)

Personally I would go with ITU resizing.

Also please note that these figures assume your 464x352 source is progressive 1:1 square pixel ratio which is usually the case with downloaed MPEG-4 DivX and MPEG-4 XviD video files.

- John "FulciLives" Coleman

P.S.
You can just replace LanczosResize with Lanczos4Resize and not have to change anything else. Just be sure to encode as PAL DVD Video 16x9 anamorphic widescreen.

*** EDIT ***
When I started this there were no other posts yet ... you guys are fast LOL

*** 2nd EDIT ***
My method makes a video that is 720x576 which is the PAL DVD Video standard. Making the video 544x576 is non-standard and asking for trouble because while it may play on that one DVD player you have what about other DVD players? What happens when that DVD player bites the dust? Since the extra "padding" is going to be fresh jet black video might as well do it because it will not eat up your bitrate and you will have a standard compliant PAL DVD Video in the end that will work on any PAL capable DVD player.

[AlanHK]

PS. In my scaling I ignored the "408x576" stipulation. If you really want that and the big letterboxing bands, use Fulci's version.

[DRP]

Thanks for that guys. Yeah the 464x352 original size AVI file is stretched. The peanut that made it obviously didn't know what he was doing because he chose a resolution that isn't exactly 4:3 for an old TV show which most certainly is exactly 4:3. So I've got a bit of correction to do. That's why I wanted 408x576 in a 544x576 frame. With a 16:9 display flag it comes out on screen as a perfect 4:3 picture inside a black frame being displayed on a 16:9 screen, which is exactly what I want.

I also found some example result images testing the various resize methods. From studying those, I agree that these new Spline methods are no better than Lanczos4Resize. Lanczos4Resize is still by far the best resizing algorithm as far as I can see. So I ended up using...

Lanczos4Resize(408,576)
AddBorders(68,0,68,0)

...which is doing exactly what I want.

[manono]

Yeah the 464x352 original size AVI file is stretched. The peanut that made it obviously didn't know what he was doing...

Possibly, but not necessarily, and in my opinion it probably was done correctly.

He's using Mod16 resolutions as he should, and if you pick a width of 464, as he did, then there is no Mod16 height that gives you a perfect 1.33:1 ratio, as 640x480 or 512x384 do. You might argue with his choice of 464 as the width, but it's perfectly possible to crop so that a resize to 464x352 (1.318:1) gives you a perfect aspect ratio. At this point, though, there's no way to really know for sure whether it's OK or not. Maybe find something big and round and measure it.

[DRP]

I wouldn't have messed around myself. Just pick a 4:3 ratio where both are divisible by 16. Just make it 512x384 and you're done. An incorrect aspect ratio is IMO far more annoying than the negligible and unnoticeably lower bits/pixel rate of the ever so slightly larger image size.