Mpv: Non-linear stretch

[conductorX]

It would be a great addition to have something like this:

kodi seems to have the option

https://github.com/xbmc/xbmc/blob/master/system/shaders/GL/1.5/gl_stretch.glsl

#version 150

uniform sampler2D img;
uniform float m_stretch;
uniform float m_alpha;
in vec2 m_cord;
out vec4 fragColor;

vec2 stretch(vec2 pos)
{
  // our transform should map [0..1] to itself, with f(0) = 0, f(1) = 1, f(0.5) = 0.5, and f'(0.5) = b.
  // a simple curve to do this is g(x) = b(x-0.5) + (1-b)2^(n-1)(x-0.5)^n + 0.5
  // where the power preserves sign. n = 2 is the simplest non-linear case (required when b != 1)
  float x = pos.x - 0.5;
  return vec2(mix(x * abs(x) * 2.0, x, m_stretch) + 0.5, pos.y);
}

void main()
{
  fragColor.rgb = texture(img, stretch(m_cord)).rgb;
  fragColor.a = m_alpha;
}

[haasn]

You can easily do pretty much exactly this with the --glsl-shaders option.

[conductorX]

it seems to need adaptation, tried to add the headers and change the functions but it doesn't work

[ghost]

What kind of brain damage is required to find this kind of "stretching" good?

[conductorX]

@wm4 it retains the geometry of the centre pixels avoiding stretching the main people/objects that are in the middle of the frame, usually produces good results, you should try it before judging.

[sarahzrf]

@conductorX I threw together a really simple working example—take a look!

https://gist.github.com/benzrf/c9909aee70e3656895820f20ac395956

You need to pass the --no-keepaspect flag to mpv for it to work right.

[conductorX]

@benzrf thank you very much for this

[sarahzrf]

no problem :)

[Akemi]

added to the wiki https://github.com/mpv-player/mpv/wiki/User-Scripts