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fix(windows): correct shader selection for sRGB-encoded FP16 framebuffer (Win11 SDR) #5106

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fix(windows): correct shader selection for sRGB-encoded FP16 framebuffer (Win11 SDR) #5106

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7 changes: 7 additions & 0 deletions src/platform/windows/display.h
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,13 @@ namespace platf::dxgi {

virtual bool is_hdr() override;
virtual bool get_hdr_metadata(SS_HDR_METADATA &metadata) override;
// Returns true when the capture source delivers FP16 storage with already
// gamma-encoded (sRGB) values, as happens with Windows 11 Auto Color
// Management (ACM) when an SDR application is displayed on an SDR monitor.
// In this case the linear shader path must NOT apply ApplySRGBCurve again
// (otherwise highlights are doubly encoded → white-out).
// Distinct from is_hdr() which checks for PQ HDR (G2084).
bool is_source_gamma_encoded_fp16();

const char *dxgi_format_to_string(DXGI_FORMAT format);
const char *colorspace_to_string(DXGI_COLOR_SPACE_TYPE type);
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21 changes: 21 additions & 0 deletions src/platform/windows/display_base.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -766,6 +766,27 @@ namespace platf::dxgi {
return desc1.ColorSpace == DXGI_COLOR_SPACE_RGB_FULL_G2084_NONE_P2020;
}

bool display_base_t::is_source_gamma_encoded_fp16() {
dxgi::output6_t output6 {};

auto status = output->QueryInterface(IID_IDXGIOutput6, (void **) &output6);
if (FAILED(status)) {
return false;
}

DXGI_OUTPUT_DESC1 desc1;
output6->GetDesc1(&desc1);

// Windows 11 Auto Color Management (ACM) composes SDR desktops into an
// FP16 framebuffer but the pixel values remain gamma-encoded (G22).
// The "linear" shader path assumes linear scRGB FP16 (G10) and applies
// ApplySRGBCurve, which double-encodes the already-sRGB G22 values,
// crushing highlights to white. Use this method to route G22+FP16 input
// through the non-linear shader path (saturate only, no curve).
return desc1.ColorSpace == DXGI_COLOR_SPACE_RGB_FULL_G22_NONE_P709
|| desc1.ColorSpace == DXGI_COLOR_SPACE_RGB_FULL_G22_NONE_P2020;
}

bool display_base_t::get_hdr_metadata(SS_HDR_METADATA &metadata) {
dxgi::output6_t output6 {};

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39 changes: 35 additions & 4 deletions src/platform/windows/display_vram.cpp
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Expand Up @@ -507,15 +507,28 @@ namespace platf::dxgi {
// Semi-planar 8-bit YUV 4:2:0
create_vertex_shader_helper(convert_yuv420_planar_y_vs_hlsl, convert_Y_or_YUV_vs);
create_pixel_shader_helper(convert_yuv420_planar_y_ps_hlsl, convert_Y_or_YUV_ps);
create_pixel_shader_helper(convert_yuv420_planar_y_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
if (display->is_source_gamma_encoded_fp16()) {
// ACM-SDR FP16: input is already sRGB-encoded; reuse non-linear shader to avoid double sRGB encoding (would cause highlight white-out)
create_pixel_shader_helper(convert_yuv420_planar_y_ps_hlsl, convert_Y_or_YUV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv420_planar_y_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
}
if (downscaling) {
create_vertex_shader_helper(convert_yuv420_packed_uv_type0s_vs_hlsl, convert_UV_vs);
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_hlsl, convert_UV_ps);
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_linear_hlsl, convert_UV_fp16_ps);
if (display->is_source_gamma_encoded_fp16()) {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_hlsl, convert_UV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_linear_hlsl, convert_UV_fp16_ps);
}
} else {
create_vertex_shader_helper(convert_yuv420_packed_uv_type0_vs_hlsl, convert_UV_vs);
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_hlsl, convert_UV_ps);
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_linear_hlsl, convert_UV_fp16_ps);
if (display->is_source_gamma_encoded_fp16()) {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_hlsl, convert_UV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_linear_hlsl, convert_UV_fp16_ps);
}
}
break;

Expand All @@ -525,6 +538,9 @@ namespace platf::dxgi {
create_pixel_shader_helper(convert_yuv420_planar_y_ps_hlsl, convert_Y_or_YUV_ps);
if (display->is_hdr()) {
create_pixel_shader_helper(convert_yuv420_planar_y_ps_perceptual_quantizer_hlsl, convert_Y_or_YUV_fp16_ps);
} else if (display->is_source_gamma_encoded_fp16()) {
// ACM-SDR FP16: input is already sRGB-encoded; reuse non-linear shader to avoid double sRGB encoding
create_pixel_shader_helper(convert_yuv420_planar_y_ps_hlsl, convert_Y_or_YUV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv420_planar_y_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
}
Expand All @@ -533,6 +549,8 @@ namespace platf::dxgi {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_hlsl, convert_UV_ps);
if (display->is_hdr()) {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_perceptual_quantizer_hlsl, convert_UV_fp16_ps);
} else if (display->is_source_gamma_encoded_fp16()) {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_hlsl, convert_UV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0s_ps_linear_hlsl, convert_UV_fp16_ps);
}
Expand All @@ -541,6 +559,8 @@ namespace platf::dxgi {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_hlsl, convert_UV_ps);
if (display->is_hdr()) {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_perceptual_quantizer_hlsl, convert_UV_fp16_ps);
} else if (display->is_source_gamma_encoded_fp16()) {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_hlsl, convert_UV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv420_packed_uv_type0_ps_linear_hlsl, convert_UV_fp16_ps);
}
Expand All @@ -553,6 +573,9 @@ namespace platf::dxgi {
create_pixel_shader_helper(convert_yuv444_planar_ps_hlsl, convert_Y_or_YUV_ps);
if (display->is_hdr()) {
create_pixel_shader_helper(convert_yuv444_planar_ps_perceptual_quantizer_hlsl, convert_Y_or_YUV_fp16_ps);
} else if (display->is_source_gamma_encoded_fp16()) {
// ACM-SDR FP16: input is already sRGB-encoded; reuse non-linear shader to avoid double sRGB encoding
create_pixel_shader_helper(convert_yuv444_planar_ps_hlsl, convert_Y_or_YUV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv444_planar_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
}
Expand All @@ -562,7 +585,12 @@ namespace platf::dxgi {
// Packed 8-bit YUV 4:4:4
create_vertex_shader_helper(convert_yuv444_packed_vs_hlsl, convert_Y_or_YUV_vs);
create_pixel_shader_helper(convert_yuv444_packed_ayuv_ps_hlsl, convert_Y_or_YUV_ps);
create_pixel_shader_helper(convert_yuv444_packed_ayuv_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
if (display->is_source_gamma_encoded_fp16()) {
// ACM-SDR FP16: input is already sRGB-encoded; reuse non-linear shader to avoid double sRGB encoding
create_pixel_shader_helper(convert_yuv444_packed_ayuv_ps_hlsl, convert_Y_or_YUV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv444_packed_ayuv_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
}
break;

case DXGI_FORMAT_Y410:
Expand All @@ -571,6 +599,9 @@ namespace platf::dxgi {
create_pixel_shader_helper(convert_yuv444_packed_y410_ps_hlsl, convert_Y_or_YUV_ps);
if (display->is_hdr()) {
create_pixel_shader_helper(convert_yuv444_packed_y410_ps_perceptual_quantizer_hlsl, convert_Y_or_YUV_fp16_ps);
} else if (display->is_source_gamma_encoded_fp16()) {
// ACM-SDR FP16: input is already sRGB-encoded; reuse non-linear shader to avoid double sRGB encoding
create_pixel_shader_helper(convert_yuv444_packed_y410_ps_hlsl, convert_Y_or_YUV_fp16_ps);
} else {
create_pixel_shader_helper(convert_yuv444_packed_y410_ps_linear_hlsl, convert_Y_or_YUV_fp16_ps);
}
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