In gstvideoaffinetransformationmeta.h , it is stated as:
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 * @matrix: the column-major 4x4 transformation matrix
 *
 * are assumed to have an origin at (0.5, 0.5, 0.5) in a left-handed coordinate
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In gstglimagesink.c , it is passed to gst_gl_get_affine_transformation_meta_as_ndc_ext (af_meta, matrix);

In gstglutils.c , gst_gl_get_affine_transformation_meta_as_ndc_ext() uses constant matrix, from_ndc_matrix[] and to_ndc_matrix[] .

I think those constant matrices also should be column major.
In addition, I think z axis should be inverted.

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static const gfloat from_ndc_matrix[] = {
// column major, Right Hand -> Left Hand
  0.5f, 0.0f, 0.0, 0.0f,
  0.0f, 0.5f, 0.0, 0.0f,
  0.0f, 0.0f, -0.5, 0.0f,
  0.5f, 0.5f, 0.5, 1.0f,
/*
  0.5f, 0.0f, 0.0, 0.5f,
  0.0f, 0.5f, 0.0, 0.5f,
  0.0f, 0.0f, 0.5, 0.5f,
  0.0f, 0.0f, 0.0, 1.0f,
*/
};

static const gfloat to_ndc_matrix[] = {
// column major, Left Hand -> Right Hand
  2.0f, 0.0f, 0.0, 0.0f,
  0.0f, 2.0f, 0.0, 0.0f,
  0.0f, 0.0f, -2.0, 0.0f,
  -1.0f, -1.0f, -1.0, 1.0f,
/*
  2.0f, 0.0f, 0.0, -1.0f,
  0.0f, 2.0f, 0.0, -1.0f,
  0.0f, 0.0f, 2.0, -1.0f,
  0.0f, 0.0f, 0.0, 1.0f,
*/
};

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I hope experts verify this point.