NTSC: use 6-taps filtering instead of 12-tap

1 files changed, 3 insertions, 3 deletions

diff --git a/src/shaders/math/color.wgsl b/src/shaders/math/color.wgsl
index 0639bf7..f5f06f8 100644
--- a/src/shaders/math/color.wgsl
+++ b/src/shaders/math/color.wgsl
@@ -27,13 +27,13 @@ fn yiqa_to_rgba(yiq: vec4f) -> vec4f {
 
 // Convert RGBA to packed luma/chroma/phase signal for NTSC processing.
 // Returns vec4f(luma, chroma_level, phase/TAU, alpha).
-// ysize: virtual scanline count (e.g. 33.*8.); drives 22.5-degree inter-line phase shift.
+// ysize: virtual scanline count (e.g. 264 lines); drives 22.5-degree inter-line phase shift.
 fn rgba_to_luma_chroma_phase(rgba: vec4f, uv_y: f32, ysize: f32) -> vec4f {
   let yiq = rgba_to_yiqa(rgba);
   let chroma_level = length(yiq.yz);
   let mscanl = (uv_y * ysize) % 2.0;
-  let phase = atan2(yiq.y, yiq.z) - 0.3926991 + mscanl * 0.19634954;
-  return vec4f(yiq.x, chroma_level, phase / TAU_COLOR, yiq.a);
+  let phase = atan2(yiq.y, yiq.z) / TAU_COLOR - (1. - mscanl * 0.5) / 16.;
+  return vec4f(yiq.x, chroma_level, phase, yiq.a);
 }
 
 // sRGB to Linear approximation