How to query the serial number of a UVC camera? - usb

Question

I have two UVC cameras in a stereoscopic setup, controlled with a C++ MediaFoundation app. I need to uniquely identify them in order to assign left and right to each physical device. This camera model has a unique serial number in the USB descriptor. However I can't seem to find a way to get the serial number while enumerating using MediaFoundation.
The MF enumeration order of these cameras is not reliably in port order; 95% of the time, camera 1 is enumerated before camera 2, while on some machines, we get camera 2 before camera 1. So finding the serial number is very important.
Things I've tried:
MediaFoundation doesn't seem to provide a direct way to get the serial number at all
By querying the MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_SYMBOLIC_LINK attribute, you can get a USB symbolic link. The docs say this can be used to call SetupDiOpenDeviceInterface however this doesn't seem to be usable to get the serial number (or the USB descriptor) either.
WinUSB can be used to open some USB devices in a generic manner, so the USB descriptor might be accessible, but this method fails on these cameras also, after passing the handle from CreateFile.
IOCTL the lowest level method, apparently you can send a IOCTL_USB_GET_NODE_CONNECTION_INFORMATION_EX to the hub device, with a port index, and it will return the descriptor from which you should be able to get the serial number. No idea how to get the hub device and port index from only the symlink though.
Related, but unresolved: How to get hardware ID when enumerating with Windows Media Foundation
I do not wish to reimplement half of the USBView example and enumerate the entire USB world just to get some specific info for a device for which I already have a handle.
Some symbolic links for USB devices can be parsed to extract the serial number, however in the case of composite devices (all the devices in question here) the symbolic link has the &MI_00# style format and does not contain the serial number in the symlink string. So it cannot simply be parsed out.
More generally, the Setup and related APIs in Win32 seem to make it easy to get information such as manufacturer, friendly name, and all sorts of other info. But serial number is conspicuously absent.
So how do you get the serial number associated with a MediaFoundation device instance?

Answer 1

You can do camera identification by USB port connection (Root-Hub-Port identifiers are the same if you don't connect new USB cards or hubs to the system)

Answer 2

Unfortunately StackOverflow doesn't give to attach images (I don't have good enough reputation).
I'll try to show data from debugger:
There is list of my available cameras
+Integrated_Webcam/R1.H2.P4/VID_1BCF&PID_2284&MI_00;
+HBVCAM FHD CAMERA/R4.H2.P4/VID_058F&PID_3821&MI_00;
+HD USB Camera/R5.H2.P5/VID_05A3&PID_9230&MI_00;
+Integrated_Webcam/R5.H2.P6/VID_1BCF&PID_2284&MI_00;
+Logitech HD Webcam C270/R1.H2.P1/VID_046D&PID_0825&MI_00;
Each string consists of Friendly camera name, Rx.Hx.Px camera connection port indexes, (i.e. Controller number"R"-Hub number"H"-Port number"P") and VID-PID-MI presentation string(vendor id, product id and interface number).
1st and 4th cameras are the same, but have different RHP indexes. These indexes I do use for camera identification.
I did USB enumerator which provides these indexes (I did this on the base of Microsoft USBView.exe application which is provided with sources in Windows SDK).
[1]: https://i.stack.imgur.com/6SQcS.png

Answer 3

Usually simple USB cameras (web cameras) doesn't have serial number or something like serial number is encoded inside USB instance ID. More expensive cameras have special drivers and you can read SN by driver.
I see only one way to know, what camera I do use now - by attached USB port. This port is unique... if you don't connect additional hubs or not insert additional USB interface cards in computer. There is USB enumeration process which provides Controller(Root)-Hub-Port enumeration indexes. I do use these indexes for camera identification.
Look on this dialog: you see 5 strings with 5 USB cameras descriptors. Each descriptor consists of "Friendly Camera Name", 3 enumeration indexes (Rx.Hx.Px) and camera vendor ID and product ID (VID and PID).
If I put different camera to the same port, my program will use this different camera. If several cameras of the same type are connected, I do differ between cameras by RHP indexes. For example, the first and the fourth camera in list are the same, but they have different
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