[vlc-devel] [PATCH 2/7] opengl: apply chroma conversion using a matrix
Romain Vimont
rom1v at videolabs.io
Wed Jan 22 13:33:44 CET 2020
Use native matrix multiplication to apply the chroma conversion.
Concretely, the generated fragment shader looked like:
uniform vec4 Coefficients[4];
uniform vec4 FillColor;
void main(void) {
float val;vec4 colors;
colors = texture2D(Texture0, TexCoord0);
val = colors.r;
vec4 color0 = vec4(val, val, val, 1);
colors = texture2D(Texture1, TexCoord1);
val = colors.r;
vec4 color1 = vec4(val, val, val, 1);
val = colors.g;
vec4 color2 = vec4(val, val, val, 1);
vec4 result = (color0 * Coefficients[0]) + Coefficients[3];
result = (color1 * Coefficients[1]) + result;
result = (color2 * Coefficients[2]) + result;
result = _main_0_0(result);
gl_FragColor = result * FillColor;
}
Now, it looks like:
uniform mat4 ConvMatrix;
uniform vec4 FillColor;
void main(void) {
vec4 texel;
vec4 pixel = vec4(0.0, 0.0, 0.0, 1.0);
texel = texture2D(Texture0, TexCoord0);
pixel[0] = texel.r;
texel = texture2D(Texture1, TexCoord1);
pixel[1] = texel.r;
pixel[2] = texel.g;
vec4 result = ConvMatrix * pixel;
result = _main_0_0(result);
gl_FragColor = result * FillColor;
}
---
modules/video_output/opengl/converter.h | 2 +-
.../video_output/opengl/fragment_shaders.c | 55 ++++++++-----------
2 files changed, 24 insertions(+), 33 deletions(-)
diff --git a/modules/video_output/opengl/converter.h b/modules/video_output/opengl/converter.h
index ceb515d268..3e79f1eda3 100644
--- a/modules/video_output/opengl/converter.h
+++ b/modules/video_output/opengl/converter.h
@@ -68,7 +68,7 @@ struct opengl_tex_converter_t
struct {
GLint Texture[PICTURE_PLANE_MAX];
GLint TexSize[PICTURE_PLANE_MAX]; /* for GL_TEXTURE_RECTANGLE */
- GLint Coefficients;
+ GLint ConvMatrix;
GLint FillColor;
GLint *pl_vars; /* for pl_sh_res */
} uloc;
diff --git a/modules/video_output/opengl/fragment_shaders.c b/modules/video_output/opengl/fragment_shaders.c
index ff5481a50b..46b65aa69b 100644
--- a/modules/video_output/opengl/fragment_shaders.c
+++ b/modules/video_output/opengl/fragment_shaders.c
@@ -90,8 +90,12 @@ tc_yuv_base_init(opengl_tex_converter_t *tc, vlc_fourcc_t chroma,
/* We place coefficient values for coefficient[4] in one array from
* matrix values. Notice that we fill values from top down instead
* of left to right.*/
- for (int j = 0; j < 4; j++)
- tc->yuv_coefficients[i*4+j] = j < 3 ? correction * matrix[j*4+i] : 0.f;
+ for (int j = 0; j < 3; j++)
+ tc->yuv_coefficients[i*4+j] = correction * matrix[j*4+i];
+ tc->yuv_coefficients[3] = 0.f;
+ tc->yuv_coefficients[7] = 0.f;
+ tc->yuv_coefficients[11] = 0.f;
+ tc->yuv_coefficients[15] = 1.f;
}
tc->yuv_color = true;
@@ -108,9 +112,9 @@ tc_base_fetch_locations(opengl_tex_converter_t *tc, GLuint program)
if (tc->yuv_color)
{
- tc->uloc.Coefficients = tc->vt->GetUniformLocation(program,
- "Coefficients");
- if (tc->uloc.Coefficients == -1)
+ tc->uloc.ConvMatrix = tc->vt->GetUniformLocation(program,
+ "ConvMatrix");
+ if (tc->uloc.ConvMatrix == -1)
return VLC_EGENERIC;
}
@@ -154,7 +158,8 @@ tc_base_prepare_shader(const opengl_tex_converter_t *tc,
const struct vlc_gl_interop *interop = tc->interop;
if (tc->yuv_color)
- tc->vt->Uniform4fv(tc->uloc.Coefficients, 4, tc->yuv_coefficients);
+ tc->vt->UniformMatrix4fv(tc->uloc.ConvMatrix, 1, GL_FALSE,
+ tc->yuv_coefficients);
for (unsigned i = 0; i < interop->tex_count; ++i)
tc->vt->Uniform1i(tc->uloc.Texture[i], i);
@@ -481,7 +486,7 @@ opengl_fragment_shader_init(opengl_tex_converter_t *tc, GLenum tex_target,
}
if (is_yuv)
- ADD("uniform vec4 Coefficients[4];\n");
+ ADD("uniform mat4 ConvMatrix;\n");
ADD("uniform vec4 FillColor;\n"
"void main(void) {\n");
@@ -495,52 +500,38 @@ opengl_fragment_shader_init(opengl_tex_converter_t *tc, GLenum tex_target,
unsigned color_count;
if (is_yuv) {
- ADD(" float val;\n"
- " vec4 colors;\n");
+ ADD(" vec4 texel;\n"
+ " vec4 pixel = vec4(0.0, 0.0, 0.0, 1.0);\n");
unsigned color_idx = 0;
for (unsigned i = 0; i < interop->tex_count; ++i)
{
const char *swizzle = swizzle_per_tex[i];
assert(swizzle);
size_t swizzle_count = strlen(swizzle);
- ADDF(" colors = %s(Texture%u, %s%u);\n", lookup, i, coord_name, i);
+ ADDF(" texel = %s(Texture%u, %s%u);\n", lookup, i, coord_name, i);
for (unsigned j = 0; j < swizzle_count; ++j)
{
- ADDF(" val = colors.%c;\n"
- " vec4 color%u = vec4(val, val, val, 1);\n",
- swizzle[j], color_idx);
+ ADDF(" pixel[%u] = texel.%c;\n", color_idx, swizzle[j]);
color_idx++;
assert(color_idx <= PICTURE_PLANE_MAX);
}
}
- ADD(" vec4 result = (color0 * Coefficients[0]) + Coefficients[3];\n");
+ if (yuv_swap_uv) {
+ ADD(" pixel = pixel.xzyw;\n");
+ }
+ ADD(" vec4 result = ConvMatrix * pixel;\n");
color_count = color_idx;
}
else
{
ADDF(" vec4 result = %s(Texture0, %s0);\n", lookup, coord_name);
+ if (yuv_swap_uv) {
+ ADD(" result = result.xzyw;\n");
+ }
color_count = 1;
}
assert(yuv_space == COLOR_SPACE_UNDEF || color_count == 3);
- for (unsigned i = 1; i < color_count; ++i)
- {
- unsigned color_idx;
- if (yuv_swap_uv)
- {
- assert(color_count == 3);
- color_idx = (i % 2) + 1;
- }
- else
- color_idx = i;
-
- if (is_yuv)
- ADDF(" result = (color%u * Coefficients[%u]) + result;\n",
- color_idx, i);
- else
- ADDF(" result = color%u + result;\n", color_idx);
- }
-
#ifdef HAVE_LIBPLACEBO
if (tc->pl_sh_res) {
const struct pl_shader_res *res = tc->pl_sh_res;
--
2.25.0
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