1 (edited by Nintendo Maniac 64 14-07-2015 06:15:05)

Topic: SVP's downscaling algorithm?

It's been stated on this forum in the past that SVP's downscaling algorithm is Bicubic A=-0.75.  However, when I actually compared it to MPC-HC's own Bicubic A=-0.75 downscaler to SVP's, I found that MPC-HC's downscaling was considerably sharper to the point that even A=-0.60 was sharper than SVP's own downscaler.

2 (edited by Nintendo Maniac 64 18-07-2015 23:07:10)

Re: SVP's downscaling algorithm?

UPDATE!  Doing some experimentation with still screenshots, it turns out that SVP's downscaler is actually the Lanczos3 algorithm, not Bicubic A=-0.75.

If I take a 1080p video screenshot and resize it to 720p with Lanczos via XnView, it gives the exact same result compared to setting SVP to resize the 1080p video to 720p while "Frames interpolation mode" is set to 'Off'.

Re: SVP's downscaling algorithm?

Nintendo Maniac 64
Doing some experimentation with still screenshots

hmm
SVP -> Information -> Last used AVS script

global resize_string="LanczosResize(1366,768)"

end of investigation

4 (edited by Nintendo Maniac 64 18-07-2015 23:24:35)

Re: SVP's downscaling algorithm?

Well for one thing, I never even thought it'd be in the AVS script.  Anything code-related is not my forte, so that would also mean I wouldn't know what kind of things would be part of the AVS script and what things would be part of the SVP program.

Re: SVP's downscaling algorithm?

well, just ask  big_smile

Re: SVP's downscaling algorithm?

Well this thread is 5 days old and nobody replied until now...

Re: SVP's downscaling algorithm?

Nintendo Maniac 64
5 days old

???
how many days / hours / minutes do you expect to answer such a question for a free software?  hmm

8 (edited by Nintendo Maniac 64 19-07-2015 00:15:06)

Re: SVP's downscaling algorithm?

Well it seemed odd that, as soon as I made a second post, it got a reply.  Are you telling me it was purely a coincidence that your first post in this thread happened to occur only 15 minutes after my second post?

Re: SVP's downscaling algorithm?

I saw this thread before, but because I didn't understand the question, or actually I didn't know the question, so I just let it been.

You can always bump it if no one saw it before, just be aware that not all know what the answer, or everyone just is busy, or just not really interested with the topics, or etc.

(Well, for me, I am classified in the last case big_smile,
it's because my eyes never bleed because of downscale no matter how strong the video emanating "canceric aura" lol
or it's because my eyes never sensitive enough to notice the different big_smile )

10 (edited by Mystery 20-07-2015 03:27:43)

Re: SVP's downscaling algorithm?

Lanczos for downsizing? Isn't that generally for upscaling? One of the devs told me previously that it was using Bicubic; although one of the Splines may be best.

11 (edited by Mystery 20-07-2015 03:34:32)

Re: SVP's downscaling algorithm?

That looks like a bug to me. If I look in generate.js, it says BicubicResize for downscaling and Lanczos for upscaling (even though SVP doesn't do any upscaling).

Just open generate.js and comment out the lines of "if", "else" and "lanczos", leaving only the Bicubic line. Or replace with Spline if you want.

12 (edited by Nintendo Maniac 64 20-07-2015 04:27:19)

Re: SVP's downscaling algorithm?

Mystery, could you just post the according snippets of code for using bicubic and spline?  As I alluded to earlier, coding is a major weak point of mine, so it's not immediately obvious to me where and what I'm supposed to do to achieve what you describe...

I mean, I know how to comment out stuff, but dang it, everything I tried didn't work - and yes I restarted SVP.

Re: SVP's downscaling algorithm?

Bicubic
https://mega.co.nz/#!OdwSAKQY!t_kA5kmJA … 2saZgzq05c

Spline36
https://mega.co.nz/#!DBQ1nYLA!lpQCSfi6K … 6LYlgJxY3o

Copy either of these file to replace generate.js and see which one you like best. Spline36 is a bit more demanding and this resize isn't running on the GPU but on the CPU so you also have to take performance into consideration.

Re: SVP's downscaling algorithm?

Since downscaling is only when using 768p laptop display and SVP has to be configured for 1080p TV, the CPU is under-utilized on the laptop's display so I'll go for Spline36

15 (edited by Nintendo Maniac 64 20-07-2015 05:27:13)

Re: SVP's downscaling algorithm?

Uhhh, there are laptops with 1600x900, 1440x900, and 1280x800 displays...not to mention the 720p and 768p TVs.

Also some people still have 1680x1050 or even 1280x1024 monitors, and others still like to use CRT monitors since low-persistence OLED monitors aren't a thing yet (on many CRT models you have to run at sub-1080p in order to have a refresh rate that isn't a flicker-fest).

16 (edited by Nintendo Maniac 64 20-07-2015 05:36:04)

Re: SVP's downscaling algorithm?

Apologies for the double-post but, at least for me, your script files make no difference* compared to the default downscaling.


*ok, it technically makes a difference, but it's so ridiculously small that it makes me wonder why such a difference even occurs because the result is still 99.9% the same and the difference is way less than a change in scaling algorithm would result in.

Re: SVP's downscaling algorithm?

I'm only configuring it for my own computer.

What if you compare the difference with madVR downscaling with those same algorithms?

18 (edited by Nintendo Maniac 64 21-07-2015 02:16:40)

Re: SVP's downscaling algorithm?

Mystery wrote:

What if you compare the difference with madVR downscaling with those same algorithms?

Well let's put it this way - bicubic in SVP looks way more like lanczos than it looks like bicubic in MPC-HC.  You could zoom in 300% and the difference between bicubic in SVP and lanczos is on level with what you'd see due to purely colorspace conversion.

For reference I do not use MadVR because it takes more CPU utilization than EVR CP + D3D fullscreen.

Re: SVP's downscaling algorithm?

madVR doesn't use CPU; only GPU.

As for Bicubic, it's not done by SVP, but is rather a standard function in AviSynth.

One thing I can think of. SVP calls Bicubic and passes some parameters to customize the sharpness. Perhaps you could play with that. Open Generate.js, search for "Bicubic" and remove the extra parameters.

Re: SVP's downscaling algorithm?

All I know is, I get worse performance with MadVR even when I'm not doing any scaling.

21 (edited by dlr5668 21-07-2015 10:03:47)

Re: SVP's downscaling algorithm?

You shouldnt ever use this feature in svp imho.
use catmull rom AR LL
http://puu.sh/j7a3Q/41811d7566.png

Re: SVP's downscaling algorithm?

dlr5668
You shouldnt ever use this feature in svp imho.
SVP's downscaling help to reduce CPU usage on slow machines.

Re: SVP's downscaling algorithm?

nemoW
SVP's downscaling help to reduce CPU usage on slow machines.
may be for laptops. if u have that slow cpu u should upgrade it asap  smile

24 (edited by Nintendo Maniac 64 22-07-2015 06:34:15)

Re: SVP's downscaling algorithm?

dlr5668 wrote:

may be for laptops. if u have that slow cpu u should upgrade it asap  smile

Not everyone has a quad core, i3s can't be overclocked, and you can't do h/w decoding for 10bit h.264 and VP9.

Also my monitor is smaller than 1080p and, other than raw pixel count and dot-pitch, no currently-available consumer monitor would be an upgrade simply because high-refresh consumer OLED monitors (regardless of whether they're strobbed or not) aren't a thing yet.

Re: SVP's downscaling algorithm?

Rendering 1080p image on 768p display is a waste of CPU resources and forces you to render with lower settings.

But since I have to configure SVP to run on the 1080p TV anyway, perhaps it won't change anything to run the CPU with full load in the same way on the smaller display.