Problem getting USB_BANDWIDTH_INFO structure

Question

I'm writing a Windows application in C++ reading images from an external USB cam and displaying them (which works nicely). I like to monitor the used USB bandwidth at the same time. I know that there exists a USB_BANDWIDTH_INFO structure ( https://docs.microsoft.com/en-us/windows/win32/api/usbuser/ns-usbuser-usb_bandwidth_info ), but I have no clue how to use it. More precisely: The structure itself is pretty clear, but how do I get/read it (didn't find any example code explaining that)?

Answer 1

According to the MSDN :

The USB_BANDWIDTH_INFO structure is used with the IOCTL_USB_USER_REQUEST I/O control request to retrieve information about the allocated bandwidth.

So you need to call DeviceIoControl with IOCTL_USB_USER_REQUEST .

Refer to the official example , you can find:

GetHostControllerInfo(
    HANDLE hHCDev, 
    PUSBHOSTCONTROLLERINFO hcInfo)
{
    USBUSER_CONTROLLER_INFO_0 UsbControllerInfo;
    DWORD                      dwError = 0;
    DWORD                      dwBytes = 0;
    BOOL                       bSuccess = FALSE;

    memset(&UsbControllerInfo, 0, sizeof(UsbControllerInfo));

    // set the header and request sizes
    UsbControllerInfo.Header.UsbUserRequest = USBUSER_GET_CONTROLLER_INFO_0;
    UsbControllerInfo.Header.RequestBufferLength = sizeof(UsbControllerInfo);

    //
    // Query for the USB_CONTROLLER_INFO_0 structure
    //
    bSuccess = DeviceIoControl(hHCDev,
            IOCTL_USB_USER_REQUEST,
            &UsbControllerInfo,
            sizeof(UsbControllerInfo),
            &UsbControllerInfo,
            sizeof(UsbControllerInfo),
            &dwBytes,
            NULL);

    if (!bSuccess)
    {
        dwError = GetLastError();
        OOPS();
    }
    else
    {
        hcInfo->ControllerInfo = (PUSB_CONTROLLER_INFO_0) ALLOC(sizeof(USB_CONTROLLER_INFO_0));
        if(NULL == hcInfo->ControllerInfo)
        {
            dwError = GetLastError();
            OOPS();
        }
        else
        {
            // copy the data into our USB Host Controller's info structure
            memcpy(hcInfo->ControllerInfo, &UsbControllerInfo.Info0, sizeof(USB_CONTROLLER_INFO_0));
        }
    }
    return dwError;
}

You can modify it like:

USBUSER_CONTROLLER_INFO_0 UsbControllerInfo;
UsbControllerInfo.Header.UsbUserRequest = USBUSER_GET_BANDWIDTH_INFORMATION;
UsbControllerInfo.Header.RequestBufferLength = sizeof(UsbControllerInfo);
USB_BANDWIDTH_INFO UsbBandInfo{};
DWORD                      dwError = 0;
DWORD                      dwBytes = 0;
BOOL                       bSuccess = FALSE;
    
bSuccess = DeviceIoControl(hHCDev,
    IOCTL_USB_USER_REQUEST,
    &UsbControllerInfo,
    sizeof(UsbControllerInfo),
    &UsbBandInfo,
    sizeof(USB_BANDWIDTH_INFO),
    &dwBytes,
    NULL);