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Specifies the conversion function from linear RGB to non-linear RGB (R'G'B'). These flags are used in the DXVA2_ExtendedFormat Structure.
Syntax
typedef enum _DXVA2_VideoTransferFunction {
DXVA2_VideoTransFuncMask = 0x1f,
DXVA2_VideoTransFunc_Unknown = 0,
DXVA2_VideoTransFunc_10 = 1,
DXVA2_VideoTransFunc_18 = 2,
DXVA2_VideoTransFunc_20 = 3,
DXVA2_VideoTransFunc_22 = 4,
DXVA2_VideoTransFunc_709 = 5,
DXVA2_VideoTransFunc_240M = 6,
DXVA2_VideoTransFunc_sRGB = 7,
DXVA2_VideoTransFunc_28 = 8
} DXVA2_VideoTransferFunction;
Constants
DXVA2_VideoTransFuncMaskValue: 0x1f Bitmask to validate flag values. This value is not a valid flag. |
DXVA2_VideoTransFunc_UnknownValue: 0 Unknown. Treat as DXVA2_VideoTransFunc_709. |
DXVA2_VideoTransFunc_10Value: 1 Linear RGB (gamma = 1.0). |
DXVA2_VideoTransFunc_18Value: 2 True 1.8 gamma, L' = L^1/1.8. |
DXVA2_VideoTransFunc_20Value: 3 True 2.0 gamma, L' = L^1/2.0. |
DXVA2_VideoTransFunc_22Value: 4 True 2.2 gamma, L' = L^1/2.2. This transfer function is used in ITU-R BT.470-2 System M (NTSC). |
DXVA2_VideoTransFunc_709Value: 5 ITU-R BT.709 transfer function. Gamma 2.2 curve with a linear segment in the lower range. This transfer function is used in BT.709, BT.601, SMPTE 296M, SMPTE 170M, BT.470, and SMPTE 274M. In addition BT-1361 uses this function within the range [0...1]. |
DXVA2_VideoTransFunc_240MValue: 6 SMPTE 240M transfer function. Gamma 2.2 curve with a linear segment in the lower range. |
DXVA2_VideoTransFunc_sRGBValue: 7 sRGB transfer function. Gamma 2.4 curve with a linear segment in the lower range. |
DXVA2_VideoTransFunc_28Value: 8 True 2.8 gamma. L' = L^1/2.8. This transfer function is used in ITU-R BT.470-2 System B, G (PAL). |
Remarks
The following table shows the formulas for the most common transfer functions. In these formulas, L is the linear value and L' is the non-linear (gamma corrected) value. These values are relative to a normalized range [0...1].
| Color space | Transfer function |
|---|---|
| sRGB (8-bit) |
L' = 12.92L, for L < 0.031308
L' = 1.055L^1/2.4− 0.055, for L >= 0.031308 |
| BT.470-2 System B, G | L' = L^0.36 |
| BT.470-2 System M | L' = L^0.45 |
| BT.709 |
L' = 4.50L, for L < 0.018
L' = 1.099L^0.45− 0.099, for L >= 0.018 |
| scRGB | L' = L |
| SMPTE 240M |
L' = 4.0L, for L < 0.0228
L' = 1.1115L^0.45− 0.01115, for L >= 0.0228 |
The following table shows the inverse formulas to obtain the original gamma-corrected values:
| Color space | Transfer function |
|---|---|
| sRGB (8-bit) |
L = 1/12.92L', for L' < 0.03928
L = ((L' + 0.055)/1055)^2.4, for L' >= 0.03928 |
| BT.470-2 System B, G | L = L'^1/0.36 |
| BT.470-2 System M | L = L'^1/0.45 |
| BT.709 |
L = L'/4.50, for L' < 0.081
L = ((L' + 0.099) / 1.099)^1/0.45, for L' >= 0.081 |
| scRGB | L = L' |
| SMPTE 240M |
L = L'/4.0, for L' < 0.0913
L= ((L' + 0.1115)/1.1115)^1/0.45, for L' >= 0.0913 |
This enumeration is equivalent to the DXVA_VideoTransferFunction enumeration used in DXVA 1.0.
If you are using the IMFMediaType interface to describe the video format, the transfer function is specified in the MF_MT_TRANSFER_FUNCTION attribute.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows Vista [desktop apps only] |
| Minimum supported server | Windows Server 2008 [desktop apps only] |
| Header | dxva2api.h |