HRESULT XAppCaptureOpenScreenshotStream(  
         const char* localId,  
         XAppCaptureScreenshotFormatFlag screenshotFormat,  
         XAppCaptureScreenshotStreamHandle* handle,  
         uint64_t* totalBytes  
)  

XAppCaptureTakeScreenshotResult takeScreenshotResult = {0};
XAppCaptureScreenshotStreamHandle handle = nullptr;
UINT64 totalBytesToRead = 0;
XAppCaptureScreenshotFormatFlag screenshotFormat = XAppCaptureScreenshotFormatFlag::SDR;
bool hdrAvailable = false;

/* ... obtain takeScreenshotResult with XAppCaptureTakeScreenshot. Refer to corresponding documentation ... */

hdrAvailable = static_cast<bool>(takeScreenshotResult.availableScreenshotFormats & XAppCaptureScreenshotFormatFlag::HDR);

/* Note: It is optional to obtain the HDR screenshot, if HDR is available. You will need to call XAppCaptureOpenScreenshotStream twice to obtain both SDR and HDR screenshots */
if (hdrAvailable)
{
    screenshotFormat = XAppCaptureScreenshotFormatFlag::HDR;
}

if (FAILED_LOG(XAppCaptureOpenScreenshotStream(takeScreenshotResult.localId, screenshotFormat, &handle, &totalBytesToRead)))
{
    return;
}

appLog.AddLog("%I64d bytes returned\n", totalBytesToRead);

/* You must always call XAppCaptureCloseScreenshotStream on an open XAppCaptureScreenshotStreamHandle to avoid a memory leak */
if (handle != nullptr)
{
    XAppCaptureCloseScreenshotStream(handle);
}