What are non-bicubic resizers?

[gelo333]

I have read information several times that for low-bitrate videos it is better to use non-bicubic resizers. Which resizers are non-bicubic?

Perhaps Lanczos? But the info for this resizer says that it should not be used with low-bitrate video.

The bilinear method is probably outdated.

You can also specify the number of tap=2 in Sinc. Will this be a non-bicubic resizer?

Need resize 1080p to 720p. Output video Bitrate is about 1000 kbps.

[Skiller]

I have read information several times that for low-bitrate videos it is better to use non-bicubic resizers.

Considering that bicubic resizers can be tweaked heavily, that is nonsense.

In fact, for what you intend to do, I would actually recommend a Mitchell–Netravali Bicubic resize (b = 1/3, c = 1/3).
In AviSynth, that's the default you get with BicubicResize.

[davexnet]

I have read information several times that for low-bitrate videos it is better to use non-bicubic resizers.

Considering that bicubic resizers can be tweaked heavily, that is nonsense.

In fact, for what you intend to do, I would actually recommend a Mitchell–Netravali Bicubic resize (b = 1/3, c = 1/3).
In AviSynth, that's the default you get with BicubicResize.

This is what I used to believe, but doing test encodes yield different file sizes, suggesting something doesn't add up.
For a short video (1900 frames) resizing from 1980x806 to 1280x536 yields these sizes

bicubicresize(1280,536,b=0.333,c=0.333) 9,982,290 bytes
bicubicresize(1280,536)                 9,978,718 bytes
bicubicresize(1280,536,b=1/3,c=1/3)    10,022,446 bytes

However, including the . to make it float matches the default

bicubicresize(1280,536,b=1./3.,c=1./3.)  9,978,718

This also works pretty well, giving a slightly sharper result that the default, but not as sharp as b=0.0,c=0.5

bicubicresize(1280,536,b=0.2,c=0.4)

[_Al_]

looks line avisynth takes b and c as 1 if given 1/3, it does not do the math in there, if not float for some reason

[jagabo]

AviSynth does the math before sending the value to the called function. 1/3, since both are integers, results in 0, which is then sent to the called function as 0.0. 1.0/3.0 is performed as floating point, so 0.333... is sent the the called function.

Basically you have two types of resizers: those that sharpen and those that blur. Sharpening will increase noise thereby increasing the bitrate requirement. Blurring will decrease noise thereby reducing the bitrate requirement. In AviSynth BiLinear() is the only one that blurs. It also most closely resembles what you eye would see when moving an image farther away (downscaling).

[gelo333]

Mitchell–Netravali Bicubic resize (b = 1/3, c = 1/3).

I tried it. Spline36 results look better and PSNR is higher.

And yet, which resizers are non-bicubic?

[jagabo]

All the resizers not named bicubic are not bicubic. Spline36 is sharper than Bibucic.

[gelo333]

The information is not always accurate. Sometimes something is not specified in the description. Therefore, I specified exactly the resizers.

[jagabo]

Your initial premise is incorrect. Just because a resizer is not bicubic doesn't make it better for compression.

[Skiller]

Spline36 results look better and PSNR is higher.

Of course Spline36 looks better (edit: before compression). PSNR needs to be taken with a big grain of salt.
Mitchell–Netravali Bicubic is rather soft, thus it compresses better.

[gelo333]

Your initial premise is incorrect. Just because a resizer is not bicubic doesn't make it better for compression.

Including for video with low bitrate?

[davexnet]

Here's a small comparison to show different compressibility of the various resize options

[Skiller]

Those results are perfectly plausible and what is to be expected.

One needs to pick the best compromise for the given bitrate somewhere between Gauss and Lanczos.
If you want as few compression artifacts as possible and don't mind the soft picture, go for Gauss.
If you need a good balance go for one of the recommended Bicubic variants. Bilinear may produce rather obvious scaling artifacts occasionally, especially with small details.

[orion44]

I have read information several times that for low-bitrate videos it is better to use non-bicubic resizers. Which resizers are non-bicubic?

Any resizer other than BicubicResize is non-bicubic resizer.

Need resize 1080p to 720p. Output video Bitrate is about 1000 kbps.

When I'm resizing 1080p video to 720p, I always use BlackmanResize, LanczosResize, or Lanczos4Resize. These three are all amazing resizers.

I never liked Spline resizers.

What's interesting is that "The Scene" has banned Lanczos and Bicubic resizers. They are forbidden for use by encoding groups. Don't know why.

When it comes to bicubic, my favorite is neutral bicubic (b=0, c=0.5). The default is too blurry, and the sharp ones don't have a pleasing look.