diff --git a/bgfx/shaders/dx11/chains/hlsl/fs_post.bin b/bgfx/shaders/dx11/chains/hlsl/fs_post.bin
index 52f2fbaa78f..4081afffd7a 100644
Binary files a/bgfx/shaders/dx11/chains/hlsl/fs_post.bin and b/bgfx/shaders/dx11/chains/hlsl/fs_post.bin differ
diff --git a/bgfx/shaders/dx9/chains/hlsl/fs_post.bin b/bgfx/shaders/dx9/chains/hlsl/fs_post.bin
index 3f2fbf2bd56..efd4837d48a 100644
Binary files a/bgfx/shaders/dx9/chains/hlsl/fs_post.bin and b/bgfx/shaders/dx9/chains/hlsl/fs_post.bin differ
diff --git a/bgfx/shaders/gles/chains/hlsl/fs_post.bin b/bgfx/shaders/gles/chains/hlsl/fs_post.bin
index b044cef536b..f892bd39fc2 100644
Binary files a/bgfx/shaders/gles/chains/hlsl/fs_post.bin and b/bgfx/shaders/gles/chains/hlsl/fs_post.bin differ
diff --git a/bgfx/shaders/glsl/chains/hlsl/fs_post.bin b/bgfx/shaders/glsl/chains/hlsl/fs_post.bin
index 74c98b2d949..76201d8f610 100644
Binary files a/bgfx/shaders/glsl/chains/hlsl/fs_post.bin and b/bgfx/shaders/glsl/chains/hlsl/fs_post.bin differ
diff --git a/bgfx/shaders/metal/chains/hlsl/fs_post.bin b/bgfx/shaders/metal/chains/hlsl/fs_post.bin
index 4ccc6e11b7b..25f3187fbe4 100644
Binary files a/bgfx/shaders/metal/chains/hlsl/fs_post.bin and b/bgfx/shaders/metal/chains/hlsl/fs_post.bin differ
diff --git a/hlsl/post.fx b/hlsl/post.fx
index f0babe68bca..81233f76b4e 100644
--- a/hlsl/post.fx
+++ b/hlsl/post.fx
@@ -99,12 +99,12 @@ VS_OUTPUT vs_main(VS_INPUT Input)
 	Output.TexCoord = Input.TexCoord;
 	Output.TexCoord += PrepareBloom
 		? 0.0f / TargetDims  // use half texel offset (DX9) to do the blur for first bloom layer
-		: 0.5f / TargetDims; // fix half texel offset correction (DX9)
+		: 0.5f / TargetDims; // fix half texel offset (DX9)
 
 	Output.ScreenCoord = Input.Position.xy / ScreenDims;
 
 	Output.SourceCoord = Input.TexCoord;
-	Output.SourceCoord += 0.5f / TargetDims;
+	Output.SourceCoord += 0.5f / TargetDims; // fix half texel offset (DX9)
 
 	Output.Color = Input.Color;
 
@@ -141,19 +141,19 @@ uniform float2 ShadowUV = float2(0.25f, 0.25f);
 uniform float3 Power = float3(1.0f, 1.0f, 1.0f);
 uniform float3 Floor = float3(0.0f, 0.0f, 0.0f);
 
-float2 GetAdjustedCoords(float2 coord, float2 centerOffset)
+float2 GetAdjustedCoords(float2 coord)
 {
 	// center coordinates
-	coord -= centerOffset;
+	coord -= 0.5f;
 
 	// apply screen scale
 	coord *= ScreenScale;
 
 	// un-center coordinates
-	coord += centerOffset;
+	coord += 0.5f;
 
 	// apply screen offset
-	coord += (centerOffset * 2.0) * ScreenOffset;
+	coord += ScreenOffset;
 
 	return coord;
 }
@@ -195,7 +195,7 @@ float2 GetShadowCoord(float2 QuadCoord, float2 SourceCoord)
 		: shadowFrac.xy;
 
 	float2 shadowCoord = (shadowFrac * shadowUV);
-	shadowCoord += 0.5f / shadowDims; // half texel offset
+	shadowCoord += 0.5f / shadowDims; // fix half texel offset (DX9)
 
 	return shadowCoord;
 }
@@ -203,8 +203,8 @@ float2 GetShadowCoord(float2 QuadCoord, float2 SourceCoord)
 float4 ps_main(PS_INPUT Input) : COLOR
 {
 	float2 ScreenCoord = Input.ScreenCoord;
-	float2 TexCoord = GetAdjustedCoords(Input.TexCoord, 0.5f);
-	float2 SourceCoord = GetAdjustedCoords(Input.SourceCoord, 0.5f);
+	float2 TexCoord = GetAdjustedCoords(Input.TexCoord);
+	float2 SourceCoord = GetAdjustedCoords(Input.SourceCoord);
 
 	// Color
 	float4 BaseColor = tex2D(DiffuseSampler, TexCoord);
diff --git a/src/osd/modules/render/bgfx/shaders/chains/hlsl/fs_post.sc b/src/osd/modules/render/bgfx/shaders/chains/hlsl/fs_post.sc
index 68fe25a32cc..6434c3dae2f 100644
--- a/src/osd/modules/render/bgfx/shaders/chains/hlsl/fs_post.sc
+++ b/src/osd/modules/render/bgfx/shaders/chains/hlsl/fs_post.sc
@@ -3,7 +3,7 @@ $input v_color0, v_texcoord0
 // license:BSD-3-Clause
 // copyright-holders:Ryan Holtz,ImJezze
 //-----------------------------------------------------------------------------
-// Defocus Effect
+// Scanline & Shadowmask Effect
 //-----------------------------------------------------------------------------
 
 #include "common.sh"
@@ -33,7 +33,7 @@ uniform vec4 u_power;
 uniform vec4 u_floor;
 
 // Parametric
-uniform vec4 u_time;
+uniform vec4 u_time; // milliseconds
 uniform vec4 u_jitter_amount;
 
 // Samplers
@@ -44,19 +44,19 @@ SAMPLER2D(s_shadow, 1);
 // Scanline & Shadowmask Pixel Shader
 //-----------------------------------------------------------------------------
 
-vec2 GetAdjustedCoords(vec2 coord, vec2 center_offset)
+vec2 GetAdjustedCoords(vec2 coord)
 {
 	// center coordinates
-	coord -= center_offset;
+	coord -= 0.5;
 
 	// apply screen scale
 	coord *= u_screen_scale.xy;
 
 	// un-center coordinates
-	coord += center_offset;
+	coord += 0.5;
 
 	// apply screen offset
-	coord += (center_offset * 2.0) * u_screen_offset.xy;
+	coord += u_screen_offset.xy;
 
 	return coord;
 }
@@ -64,19 +64,19 @@ vec2 GetAdjustedCoords(vec2 coord, vec2 center_offset)
 // vector screen has the same quad texture coordinates for every screen orientation, raster screen differs
 vec2 GetShadowCoord(vec2 QuadCoord, vec2 SourceCoord)
 {
-	vec2 QuadTexel = vec2(1.0, 1.0) / u_quad_dims.xy;
+	vec2 QuadTexel = vec2(1.0, 1.0) / (u_quad_dims.xy - 0.5f);
 
 	vec2 canvasCoord = QuadCoord + u_shadow_uv_offset.xy / u_quad_dims.xy;
 
 	vec2 shadowUV = u_shadow_uv.xy;
 	vec2 shadowCount = u_shadow_count.xy;
 
-	// swap x/y vector and raster in screen mode (not source mode)
+	// swap x/y in screen mode (not source mode)
 	canvasCoord = u_swap_xy.x > 0.0
 		? canvasCoord.yx
 		: canvasCoord.xy;
 
-	// swap x/y vector and raster in screen mode (not source mode)
+	// swap x/y in screen mode (not source mode)
 	shadowCount = u_swap_xy.x > 0.0
 		? shadowCount.yx
 		: shadowCount.xy;
@@ -85,7 +85,7 @@ vec2 GetShadowCoord(vec2 QuadCoord, vec2 SourceCoord)
 
 	vec2 shadowFrac = fract(canvasCoord / shadowTile);
 
-	// swap x/y raster in screen mode (not vector and not source mode)
+	// swap x/y in screen mode (not source mode)
 	shadowFrac = u_swap_xy.x > 0.0
 		? shadowFrac.yx
 		: shadowFrac.xy;
@@ -97,7 +97,7 @@ vec2 GetShadowCoord(vec2 QuadCoord, vec2 SourceCoord)
 
 void main()
 {
-	vec2 BaseCoord = GetAdjustedCoords(v_texcoord0, vec2(0.5, 0.5));
+	vec2 BaseCoord = GetAdjustedCoords(v_texcoord0);
 
 	// Color
 	vec4 BaseColor = texture2D(s_tex, BaseCoord);
@@ -136,8 +136,8 @@ void main()
 
 		float ColorBrightness = 0.299 * BaseColor.r + 0.587 * BaseColor.g + 0.114 * BaseColor.b;
 
-		float ScanCoord = BaseCoord.y * u_source_dims.y * u_scanline_scale.x * 3.1415927;
-		float ScanCoordJitter = u_scanline_jitter.x * u_jitter_amount.x * 1.618034;
+		float ScanCoord = BaseCoord.y * u_source_dims.y * u_scanline_scale.x * 3.1415927; // PI
+		float ScanCoordJitter = u_scanline_jitter.x * u_jitter_amount.x * 1.618034; // PHI
 		float ScanSine = sin(ScanCoord + ScanCoordJitter);
 		float ScanlineWide = u_scanline_height.x + u_scanline_variation.x * max(1.0, u_scanline_height.x) * (1.0 - ColorBrightness);
 		float ScanSineScaled = pow(ScanSine * ScanSine, ScanlineWide);
@@ -149,7 +149,7 @@ void main()
 	// Hum Bar Simulation
 	if (u_humbar_alpha.x > 0.0f)
 	{
-		float HumTimeStep = fract(u_time.x * 0.001);
+		float HumTimeStep = fract(u_time.x * u_humbar_hertz_rate.x);
 		float HumBrightness = 1.0 - fract(BaseCoord.y + HumTimeStep) * u_humbar_alpha.x;
 		BaseColor.rgb *= HumBrightness;
 	}