[vlc-commits] direct3d11: fix HDR rendering on LDR screens
Steve Lhomme
git at videolan.org
Fri Mar 3 16:02:54 CET 2017
vlc | branch: master | Steve Lhomme <robUx4 at videolabs.io> | Thu Mar 2 17:28:38 2017 +0100| [8b5530e5cf09306dfc8e3132d63392f6188cbe5c] | committer: Jean-Baptiste Kempf
direct3d11: fix HDR rendering on LDR screens
The wide contrast provided by HDR results in washed out colors when displayed
on an LDR (non-HDR) screen. To fix this we need to do some tone mapping in
linear space. The tone mapping used here comes from [1].
The pixel shader source is constructed based on the video input characteristics.
When the source is LDR no tone mapping or transfer adjustment is done.
For now we assume the screen is using sRGB transfer.
1: http://filmicworlds.com/blog/filmic-tonemapping-operators/
Signed-off-by: Jean-Baptiste Kempf <jb at videolan.org>
> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=8b5530e5cf09306dfc8e3132d63392f6188cbe5c
---
modules/video_output/win32/direct3d11.c | 99 ++++++++++++++++++++++++++++++---
1 file changed, 92 insertions(+), 7 deletions(-)
diff --git a/modules/video_output/win32/direct3d11.c b/modules/video_output/win32/direct3d11.c
index e24d9a0..836efa8 100644
--- a/modules/video_output/win32/direct3d11.c
+++ b/modules/video_output/win32/direct3d11.c
@@ -110,6 +110,8 @@ struct vout_display_sys_t
{
vout_display_sys_win32_t sys;
+ video_transfer_func_t display_transfer; /* TODO may go in vout_display_info_t */
+
#if !VLC_WINSTORE_APP
HINSTANCE hdxgi_dll; /* handle of the opened dxgi dll */
HINSTANCE hd3d11_dll; /* handle of the opened d3d11 dll */
@@ -298,6 +300,31 @@ static const char* globPixelShaderDefault = "\
float4 Texture : TEXCOORD0;\
};\
\
+ /* see http://filmicworlds.com/blog/filmic-tonemapping-operators/ */\
+ inline float hable(float x) {\
+ const float A = 0.15, B = 0.50, C = 0.10, D = 0.20, E = 0.02, F = 0.30;\
+ return ((x * (A*x + (C*B))+(D*E))/(x * (A*x + B) + (D*F))) - E/F;\
+ }\
+ \
+ inline float3 hable(float3 x) {\
+ x.r = hable(x.r);\
+ x.g = hable(x.g);\
+ x.b = hable(x.b);\
+ return x;\
+ }\
+ \
+ inline float3 sourceToLinear(float3 rgb) {\
+ %s;\
+ }\
+ \
+ inline float3 linearToDisplay(float3 rgb) {\
+ %s;\
+ }\
+ \
+ inline float3 toneMapping(float3 rgb) {\
+ %s;\
+ }\
+ \
float4 main( PS_INPUT In ) : SV_TARGET\
{\
float4 sample;\
@@ -308,7 +335,13 @@ static const char* globPixelShaderDefault = "\
rgba.y = sample.y + WhitePointY;\
rgba.z = sample.z + WhitePointZ;\
rgba.a = sample.a * Opacity;\
- return saturate(mul(rgba, Colorspace));\
+ rgba = mul(rgba, Colorspace);\
+ float opacity = rgba.a * Opacity;\
+ float3 rgb = float3(rgba.r, rgba.g, rgba.b);\
+ rgb = sourceToLinear(rgb);\
+ rgb = toneMapping(rgb);\
+ rgb = linearToDisplay(saturate(rgb));\
+ return float4(rgb, saturate(opacity));\
}\
";
@@ -1385,6 +1418,8 @@ static int Direct3D11Open(vout_display_t *vd, video_format_t *fmt)
return VLC_EGENERIC;
}
#endif
+ /* TODO adjust the swapchain transfer function based on the source */
+ sys->display_transfer = TRANSFER_FUNC_SRGB;
// look for the requested pixel format first
sys->picQuadConfig = GetOutputFormat(vd, fmt->i_chroma, 0, true, false);
@@ -1531,11 +1566,16 @@ static ID3DBlob* CompileShader(vout_display_t *vd, const char *psz_shader, bool
return pShaderBlob;
}
-static HRESULT CompilePixelShader(vout_display_t *vd, const d3d_format_t *format, ID3D11PixelShader **output)
+static HRESULT CompilePixelShader(vout_display_t *vd, const d3d_format_t *format,
+ video_transfer_func_t transfer, ID3D11PixelShader **output)
{
vout_display_sys_t *sys = vd->sys;
const char *psz_sampler;
+ const char *psz_src_transform = "return rgb";
+ const char *psz_display_transform = "return rgb";
+ const char *psz_tone_mapping = "return rgb";
+
switch (format->formatTexture)
{
case DXGI_FORMAT_NV12:
@@ -1560,16 +1600,61 @@ static HRESULT CompilePixelShader(vout_display_t *vd, const d3d_format_t *format
break;
default:
vlc_assert_unreachable();
+ }
+ video_transfer_func_t src_transfer;
+ switch (transfer)
+ {
+ case TRANSFER_FUNC_SMPTE_ST2084:
+ /* ST2084 to Linear */
+ psz_src_transform =
+ "rgb = pow(rgb, 1.0/78.843750);\
+ rgb = max(rgb - 0.835938, 0.0) / (18.851562 - 18.687500 * rgb);\
+ rgb = pow(rgb, 1.0/0.159302);\
+ return rgb";
+ src_transfer = TRANSFER_FUNC_LINEAR;
+ break;
+ default:
+ src_transfer = transfer;
+ break;
+ }
+
+ if (src_transfer != sys->display_transfer)
+ {
+ switch (sys->display_transfer)
+ {
+ case TRANSFER_FUNC_SRGB:
+ if (src_transfer == TRANSFER_FUNC_LINEAR)
+ {
+ /* Linear to sRGB */
+ psz_display_transform = "return pow(rgb, 1.0 / 2.2)";
+
+ if (transfer == TRANSFER_FUNC_SMPTE_ST2084)
+ {
+ /* HDR tone mapping */
+ psz_tone_mapping =
+ "static const float3 HABLE_DIV = hable(11.2);\
+ rgb = hable(32.0 * rgb) / HABLE_DIV;\
+ return rgb";
+ }
+ break;
+ }
+ default:
+ msg_Warn(vd, "don't know how to transfer from %d to %d", src_transfer, sys->display_transfer);
+ break;
+ }
}
- char *shader = malloc(strlen(globPixelShaderDefault) + 32 + strlen(psz_sampler));
+ char *shader = malloc(strlen(globPixelShaderDefault) + 32 + strlen(psz_sampler) +
+ strlen(psz_src_transform) + strlen(psz_display_transform) +
+ strlen(psz_tone_mapping));
if (!shader)
{
msg_Err(vd, "no room for the Pixel Shader");
return E_OUTOFMEMORY;
}
- sprintf(shader, globPixelShaderDefault, sys->legacy_shader ? "" : "Array", psz_sampler);
+ sprintf(shader, globPixelShaderDefault, sys->legacy_shader ? "" : "Array", psz_src_transform,
+ psz_display_transform, psz_tone_mapping, psz_sampler);
ID3DBlob *pPSBlob = CompileShader(vd, shader, true);
free(shader);
@@ -1720,7 +1805,7 @@ static int Direct3D11CreateResources(vout_display_t *vd, video_format_t *fmt)
sys->legacy_shader = !CanUseTextureArray(vd);
vd->info.is_slow = !is_d3d11_opaque(fmt->i_chroma);
- hr = CompilePixelShader(vd, sys->picQuadConfig, &sys->picQuadPixelShader);
+ hr = CompilePixelShader(vd, sys->picQuadConfig, fmt->transfer, &sys->picQuadPixelShader);
if (FAILED(hr))
{
#ifdef HAVE_ID3D11VIDEODECODER
@@ -1728,7 +1813,7 @@ static int Direct3D11CreateResources(vout_display_t *vd, video_format_t *fmt)
{
sys->legacy_shader = true;
msg_Dbg(vd, "fallback to legacy shader mode");
- hr = CompilePixelShader(vd, sys->picQuadConfig, &sys->picQuadPixelShader);
+ hr = CompilePixelShader(vd, sys->picQuadConfig, fmt->transfer, &sys->picQuadPixelShader);
}
#endif
if (FAILED(hr))
@@ -1740,7 +1825,7 @@ static int Direct3D11CreateResources(vout_display_t *vd, video_format_t *fmt)
if (sys->d3dregion_format != NULL)
{
- hr = CompilePixelShader(vd, sys->d3dregion_format, &sys->pSPUPixelShader);
+ hr = CompilePixelShader(vd, sys->d3dregion_format, TRANSFER_FUNC_SRGB, &sys->pSPUPixelShader);
if (FAILED(hr))
{
ID3D11PixelShader_Release(sys->picQuadPixelShader);
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