DXGI_DDI_RATIONAL structure (dxgiddi.h)
The DXGI_DDI_RATIONAL structure describes a fractional value that represents vertical and horizontal frequencies of a display mode (that is, vertical sync and horizontal sync).
Syntax
typedef struct DXGI_DDI_RATIONAL {
[in] UINT Numerator;
[in] UINT Denominator;
} DXGI_DDI_RATIONAL;
Members
[in] Numerator
The numerator of the frequency fraction.
[in] Denominator
The denominator of the frequency fraction.
Remarks
Vertical frequencies are stored in Hertz (Hz); horizontal frequencies are stored in kilohertz (kHz). The dynamic range of this encoding format, given 10^-7 resolution, is {0..(2^32 - 1) / 10^7}. This range translates to {0..428.4967296} [Hz] for vertical frequencies and {0..428.4967296} [kHz] for horizontal frequencies. This submicrosecond precision range is acceptable even for a provided application. (An error of one microsecond for video signal synchronization would imply a time drift with a cycle of 10^7/(60 x 60 x 24) = 115.741 days.)
For a rational number with a finite fractional sequence, use a denominator of the form 10^(length of fractional sequence). For a rational number without a finite fractional sequence, a sequence that exceeds the precision that the dynamic range of the denominator allows, or an irrational number, use an appropriate ratio of integers that best represents the value.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Available in Windows Vista and later versions of the Windows operating systems. |
| Header | dxgiddi.h (include D3d10umddi.h) |