Compositor_FrameTiming

Provides a single frame's timing information to the app

Always set 'size' to sizeof(Compositor_FrameTiming) for proper versioning and avoid memory corruption. In C# use:

(uint)System.Runtime.InteropServices.Marshal.SizeOf(typeof(Compositor_FrameTiming));

Properties

frameStart - Time reference for each frame. This won't necessarily be evenly spaced.

frameVSync - Time from frameStart until the next VSync. Using (current.frameStart + current.frameVSync) - (previous.frameStart + previous.frameVSync) should be a reliable way to measure frame intervals.

droppedFrames - Number of droppedFrames as reported by DXGI's GetFrameStatistics since the previous frame. This is a delta of PresentRefreshCount since the last time we called it. It is stored unsigned, but has been known to go negative, so should be cast to an int before using.

frameIndex - Incremented each frame. Can be used to call GetFrameTiming at a lower frequency than it's being updated to iterate through the history until you see a frame you recognize.

pose - Hmd pose used to render this frame.

struct Compositor_FrameTiming
{
    uint32_t size; // sizeof(Compositor_FrameTiming)
    double frameStart;
    float frameVSync; // seconds from frame start
    uint32_t droppedFrames;
    uint32_t frameIndex;
    vr::TrackedDevicePose_t pose;
};