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glcolorconvert: fix RGB,rectangle->planar YUV conversion

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Converting to GRAY is no fun.  Another case of normalized vs unnormalized
texture coordinates.
This commit is contained in:
Matthew Waters 2016-02-02 15:14:25 +11:00 committed by Tim-Philipp Müller
parent b4704301c6
commit e2c9f4570c
1 changed files with 8 additions and 5 deletions
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13
gst-libs/gst/gl/gstglcolorconvert.c
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@ -248,10 +248,14 @@ static const struct shader_templ templ_RGB_to_PLANAR_YUV =
* @chroma_sampling. The result is the average of all the values in the
* block computed with a rolling average.
*/
"vec2 size = vec2(width, height);\n"
"vec2 pos = texcoord * size;\n"
"vec2 unnormalization;\n"
"if (texcoord.x == v_texcoord.x) {\n"
" unnormalization = vec2(width, height);\n"
"} else {\n"
" unnormalization = vec2 (1.0);\n"
"}\n"
/* scale for chroma size */
"vec2 chroma_pos = texcoord * chroma_sampling * size;\n"
"vec2 chroma_pos = texcoord * chroma_sampling * unnormalization;\n"
/* offset chroma to the center of the first texel in the block */
"chroma_pos -= clamp(chroma_sampling * 0.5 - 0.5, vec2(0.0), chroma_sampling);\n"
"if (chroma_pos.x < width && chroma_pos.y < height) {\n"
@ -260,13 +264,12 @@ static const struct shader_templ templ_RGB_to_PLANAR_YUV =
" for (int j = 0; j < int(chroma_sampling.y); j++) {\n"
" int n = (i+1)*(j+1);\n"
" delta.y = float(j);\n"
" vec4 sample = texture2D(tex, (chroma_pos + delta) / size).%c%c%c%c;\n"
" vec4 sample = texture2D(tex, (chroma_pos + delta) / unnormalization).%c%c%c%c;\n"
/* rolling average */
" uv_texel = (float(n-1) * uv_texel + sample) / float(n);\n"
" }\n"
" }\n"
"}\n"
"yuv.x = rgb_to_yuv (texel.rgb, offset, coeff1, coeff2, coeff3).x;\n"
"yuv.yz = rgb_to_yuv (uv_texel.rgb, offset, coeff1, coeff2, coeff3).yz;\n"
"gl_FragData[0] = vec4(yuv.x, 0.0, 0.0, 1.0);\n"