feat: support straight alpha in mixer shader

CasparCG · Jan 21, 2025 · c490d6b · c490d6b
1 parent e221039
commit c490d6b
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Showing 3 changed files with 8 additions and 2 deletions.
diff --git a/src/accelerator/ogl/image/image_kernel.cpp b/src/accelerator/ogl/image/image_kernel.cpp
@@ -308,6 +308,7 @@ struct image_kernel::impl
         // Setup shader
         shader_->use();
 
+        shader_->set("is_straight_alpha", params.pix_desc.is_straight_alpha);
         shader_->set("plane[0]", texture_id::plane0);
         shader_->set("plane[1]", texture_id::plane1);
         shader_->set("plane[2]", texture_id::plane2);

diff --git a/src/accelerator/ogl/image/shader.frag b/src/accelerator/ogl/image/shader.frag
@@ -8,6 +8,8 @@ uniform sampler2D	plane[4];
 uniform sampler2D	local_key;
 uniform sampler2D	layer_key;
 
+uniform bool        is_straight_alpha;
+
 uniform mat3		color_matrix;
 uniform vec3		luma_coeff;
 uniform bool		has_local_key;
@@ -495,7 +497,7 @@ vec4 get_rgba_color()
 		{
 			float y = get_sample(plane[0], TexCoord.st / TexCoord.q).g * precision_factor[0];
 			float cb = get_sample(plane[1], TexCoord.st / TexCoord.q).b * precision_factor[1];
-			float cr = get_sample(plane[1], TexCoord.st / TexCoord.q).r * precision_factor[1];			
+			float cr = get_sample(plane[1], TexCoord.st / TexCoord.q).r * precision_factor[1];
 			return ycbcra_to_rgba(y, cb, cr, 1.0);
 		}
     }
@@ -505,6 +507,8 @@ vec4 get_rgba_color()
 void main()
 {
     vec4 color = get_rgba_color();
+    if (is_straight_alpha)
+        color.rgb *= color.a;
     if (chroma)
         color = chroma_key(color);
     if(levels)

diff --git a/src/core/frame/pixel_format.h b/src/core/frame/pixel_format.h
@@ -83,7 +83,8 @@ struct pixel_format_desc final
     {
     }
 
-    pixel_format       format = pixel_format::invalid;
+    pixel_format       format            = pixel_format::invalid;
+    bool               is_straight_alpha = false;
     std::vector<plane> planes;
     core::color_space  color_space = core::color_space::bt709;
 };