HRESULT XAppCaptureRecordTimespan(
  const SYSTEMTIME * startTimestamp,
  uint64_t durationInMilliseconds,
  XAppCaptureLocalResult * result
)

XAppCaptureLocalResult appCaptureLocalResult = { 0 };
uint64_t durationInMs = 5000; /* 5 seconds, for example */

if (SUCCEEDED(XAppCaptureRecordTimespan(nullptr, durationInMs, &appCaptureLocalResult))) // record the past 5000ms (startTimestamp is calculated automatically)
{
    appLog.AddLog("StartTimestamp: %llu, Duration (ms): %llu, File Size (bytes): %llu, Width: %d, Height: %d, Encoding: %d, Color Format: %d\n", appCaptureLocalResult.clipStartTimestamp, appCaptureLocalResult.durationInMilliseconds, appCaptureLocalResult.fileSizeInBytes,
        appCaptureLocalResult.width, appCaptureLocalResult.height, appCaptureLocalResult.encoding, appCaptureLocalResult.colorFormat);
}

void SubtractMsDurationFromFileTimeToULarge(_In_ FILETIME* pFileTime, _In_ uint64_t durationInMs, _Out_ ULARGE_INTEGER* pUlResultingTime)
{
    ULARGE_INTEGER fileTimeAsUlarge;

    fileTimeAsUlarge.LowPart = pFileTime->dwLowDateTime;
    fileTimeAsUlarge.HighPart = pFileTime->dwHighDateTime;

    // Convert ms to 100 ns intervals, the convention used by FILETIME
    pUlResultingTime->QuadPart = fileTimeAsUlarge.QuadPart - (durationInMs * 10000LL);
}

void ULargeToSystemTime(_In_ ULARGE_INTEGER ulInputTime, _Out_ SYSTEMTIME* pOutputTime)
{
    FILETIME inputAsFiletime;

    inputAsFiletime.dwLowDateTime = ulInputTime.LowPart;
    inputAsFiletime.dwHighDateTime = ulInputTime.HighPart;

    FileTimeToSystemTime(&inputAsFiletime, pOutputTime);
}

void YourFunction()
{
    XAppCaptureLocalResult appCaptureLocalResult = { 0 }; 
    uint64_t durationInMs = 8000; /* 8 seconds, for example */
    FILETIME now;
    ULARGE_INTEGER calculatedStartTimestamp;
    SYSTEMTIME startTimestampAsSystemTime;
    XAppCaptureVideoCaptureSettings captureSettings = { 0 };

    GetSystemTimeAsFileTime(&now);
    SubtractMsDurationFromFileTimeToULarge(&now, durationInMs, &calculatedStartTimestamp);
    ULargeToSystemTime(calculatedStartTimestamp, &startTimestampAsSystemTime);
    
    if (SUCCEEDED(XAppCaptureGetVideoCaptureSettings(&captureSettings)) && captureSettings.isCaptureByGamesAllowed && (captureSettings.maxRecordTimespanDurationInMs >= durationInMs)){
        if (SUCCEEDED(XAppCaptureRecordTimespan(&startTimestampAsSystemTime, durationInMs, &appCaptureLocalResult))) // record 8000ms starting from 8000ms before now (calculated manually)
        {
            appLog.AddLog("StartTimestamp: %llu, Duration (ms): %llu, File Size (bytes): %llu, Width: %d, Height: %d, Encoding: %d, Color Format: %d\n", appCaptureLocalResult.clipStartTimestamp, appCaptureLocalResult.durationInMilliseconds, appCaptureLocalResult.fileSizeInBytes,
                appCaptureLocalResult.width, appCaptureLocalResult.height, appCaptureLocalResult.encoding, appCaptureLocalResult.colorFormat);
        }
    }
}

XAppCaptureLocalResult appCaptureLocalResult = { 0 }; 
uint64_t durationInMs = 10000; /* 10 seconds, for example */
SYSTEMTIME nowStartTimestamp;
XAppCaptureVideoCaptureSettings captureSettings = { 0 };

GetSystemTime(&nowStartTimestamp);

if (SUCCEEDED(XAppCaptureGetVideoCaptureSettings(&captureSettings)) && captureSettings.isCaptureByGamesAllowed){
    if (SUCCEEDED(XAppCaptureRecordTimespan(&nowStartTimestamp, durationInMs, &appCaptureLocalResult))) // record the next 10 seconds starting now
    {
        appLog.AddLog("StartTimestamp: %llu, Duration (ms): %llu, File Size (bytes): %llu, Width: %d, Height: %d, Encoding: %d, Color Format: %d\n", appCaptureLocalResult.clipStartTimestamp, appCaptureLocalResult.durationInMilliseconds, appCaptureLocalResult.fileSizeInBytes,
            appCaptureLocalResult.width, appCaptureLocalResult.height, appCaptureLocalResult.encoding, appCaptureLocalResult.colorFormat);
    }
}