Avidemux Forum

Avidemux => Main version 2.6 => Topic started by: dokipubast on March 16, 2016, 07:46:56 PM

Title: Need an SR rescaling filter for Avidemux
Post by: dokipubast on March 16, 2016, 07:46:56 PM
Something like Genuine Fractals/Perfect Resize. For upscaling by a factor of ~3:1. Is there anything that is superior to bicubic/lanzcos3?
Title: Re: Need an SR rescaling filter for Avidemux
Post by: Jan Gruuthuse on March 17, 2016, 06:16:06 AM
Depends from what resolution you start?
Just tested swsResize can only take 720p to 1440p (2:1)
vdpau and OpenGL are not doing this for now.

make a test clip from the source you want to upscale (10 seconds)
and test what suits you best.
i prepared a small test from 720p to 1140p and uploaded this to our YouTube Avidemux Demo (https://www.youtube.com/channel/UC7ycUgCIuOlChtpiTFfLTmw)
- 720p small source clip
- upscaled 720p bilinear to 1440p
- upscaled 720p Bicubic to 1440p
- upscaled 720p Lanzcos3 to 1440p
Title: Re: Need an SR rescaling filter for Avidemux
Post by: AQUAR on March 17, 2016, 10:42:39 AM
If you want upsizing with a higher quality than that provided by the built in filters you have to pair ADM with Avisynth or Vapoursynth.
Eg: Avisynth can do Spline interpolation with Spline64Resize (8 sample points and is quite sharp with very little ringing).

If its just to upscale a movie for a 1080P screen I wouldn't bother.
There was a discussion some time ago about up scaling on the fly vs re scaling the source.
Both have merit depending on your goals.
Title: Re: Need an SR rescaling filter for Avidemux
Post by: xpmule on March 17, 2016, 05:52:03 PM
I am no expert but i had done some digging on this way back..
And i actually just changed my mind before seeing this topic on something.
I had converted two seasons of a TV show from XVID AVI format to AVC MKV
But when i did it recently i used Lanscoz and i rarely ever use that algo.
SO i changed my mind and i am redoing all my video's with Bicubic (what i normally always use)
Why ?
Lancosz produces a more blurry smoothed out effect and Bicubic is more an accurate sharper result.
OP it sounds like you may already know this but i say it for the readers too ;)

Your topic here is interesting though i have not heard of that before.
When ever i resize a picture with Adobe Fireworks i always use Bicubic.
And i have done tedious comparisons before with simple images and yeah Bicubic was definitely better looking.

I mention all this because Lanscoz is the default i noticed long ago with Avidemux.
I take it that was done because that is what you all out there consider as "good looking"
Not just with Avidemux but with all resizing of pictures or videos on all programs on the whole web.
People seem to prefer a blurry picture over a sharp clear one for some reason.

Why do i care so much ?

I collect TV shows and they are often lower resolution (often 720p or higher is just not available)
My 32" TV screen hooked up to my Win7 x64 PC is running Windows Media Center
and i have my screen setup for a custom resolution (close to 720p) on purpose !
I can do 1080p if i wanted to but for anything not watching video it make things too small
and changing the DPI etc is just dumb LOL

So that means..
What happens is, i have a video say 624x352 being played that is going to get stretched on the fly by my Codec to 720p.
"Stretched" = the same thing as resizing.
So think about it.. your videos are going to be resized again after with the codec right ?
What would be better to have then a video that is more blurry or more sharp ?
Sharp obviously.. stretching an already blurry video is just going to compound the blurryness.
And you all may say oh well the difference is so small between Lancosz & Bicubic who cares it won't make any difference.
But you'd be wrong LOL
624x352 stretched to 1280x720 is a huge stretch that will amplify the small differences between the two.

And why did i re-encode my videos when the golden rule is never re-encode ?
LAV-Codec on Windows supports Hardware GPU acceleration and other post processing.
Which does not work for XVID / DIVX based AVI files..

I also had the subs sitting in the folder with my AVI's
And i though well.. i would rather have them embedded into MKV containers.
I have have the TV series as 720p BluRay rips with Subs anyway so i can embed those two.
They changed to HD format mid way through the TV series so i am trying to collate them all with some consistency for all episodes.
Before i change things i will have half the series with Hardware acceleration enabled and the other half with out.
After i am done they will all be the same format, codec, container etc.

I mentioned that because intent is key.. why you are doing things and what the effects are.
Like what do you hope to accomplish ? In my case i had a bunch of reasons.

Anyway about the Feature request etc here..
Maybe try and find some code that can be used to port it to Avidemux and post a link to it.
If this algo offers better accuracy i am for sure all for it :)

And don't forget guys we may have done some quick searching on this with Google before.
But i bet a LOT of Avidemux users have no bloody idea what algo does what and they prob use the default.. which i think sucks !

Algo's !!! I am a nerd hahahah
Title: Re: Need an SR rescaling filter for Avidemux
Post by: AQUAR on March 18, 2016, 03:55:48 AM
@ xpmule
The results of using various scaling algorithms is subjective.
The processing speed to accomplish the up/down scaling is also subjective in merit.
The worth of up scaling also depends on viewing distance and screen size.
The artefacts on down scaling is also different to up scaling for different methods.
Consider the type of "video" - movie or anime.

This just points out that what works for you may not work for some one else.

I do know that various up scaling methods have a ranking order by general consensus.
If you have time to spend on getting the best result then there are filter options that can be paired to ADM that are worthy of trying out.

That's what the OP was asking for - something else than the built in ADM scaling filters.