Romain Vimont authored Mar 16, 2022 and Hugo Beauzée-Luyssen committed Mar 21, 2022

Some YUV 4:2:2 formats are packed: two consecutive pixels are stored
using 4 values (for example [Y1 U Y2 V]).

But in OpenGL we cannot have both:
 - a single texture, and
 - a correct native interpolation for both Y and UV components.

To avoid the problem, the current implementation just dropped the Y2
value, so the pictures were rendered at half the horizontal resolution.

To render at full definition, upload the single plane into two separate
OpenGL textures:
 - one in GL_RG, to read each Y value in a different texel;
 - one in GL_RGBA, to read both U and V values in a single texel.

As a consequence, pic->i_planes is not necessarily equal to
interop->tex_count anymore (there might be 1 picture plane but 2
textures).

Fixes #26712