In 2003, Microsoft added a standard USB video class (UVC) driver, Usbvideo.sys, to Windows XP as part of SP2. It is also included in all installations of Windows Server 2003 and Vista. This means that if you have a webcam or other video device that has a USB device driver that conforms to the USB video class specification, you can just plug it into your computer and it will work! No driver installation necessary. Any video device that has the “Designed for Windows Vista” logo must have a UVC compliant driver. The really cool thing about the UVC driver is that it is not just provided on Windows, but also on Linux and Mac OS-X, so a video device that complies with this spec will work anywhere!

Documentation for the Microsoft UVC driver

A description of functions supported by Microsoft’s UVC driver (from a system administrator’s perspective). Can be found here: Availability of the USB video class driver for Windows XP

An updated driver that allows UVC-compliant cameras to render DV data from the host PC back to the device, and capture MPEG2 TS data from the device to the host PC can be downloaded here: Update for USB Video Class (UVC) driver in Windows XP Home and Professional with Service Pack 2

Specifications for USB classes, including UVC, are available on the USB Implementer’s forum at: Approved Class Specification Documents

The main programming documentation for the UVC driver is in the online MSDN library under: “Win32 and COM development – Windows Driver Kit – Device and Driver Technologies – Streaming Media – Design Guide – AVStream Minidrivers – USB Video Class Driver”. URL: Windows Driver Kit: Streaming Media Devices: USB Video Class Driver

(The above documentation is part of the Windows Driver Kit (WDK). This documentation is not included in the Windows SDK docs or in the MSDN Library for VS2005. You can download the documentation for the WDK from this page: Windows Driver Kit (WDK) Documentation)

Programming interfaces for the UVC driver

A Windows application can access the UVC driver via Microsoft DriectShow (Microsoft DirectShow 9.0), or via the kernel stream (also known as AVStream) interface, ks.sys (Windows Driver Kit: Streaming Media Devices: Kernel Streaming). Note that the MS UVC driver is a type of AVStream Minidriver. AVStream Minidrivers (Windows Driver Kit: Streaming Media Devices : AVStream Overview) conform to the Windows Driver Model (WDM) (Windows Driver Kit: Kernel-Mode Driver Architecture: Introduction to WDM), and WDM drivers are kernel mode drivers.

Next Post: Writing an application that uses the Microsoft UVC driver

I would like to write a video capture program for my Logitech web cam with a UVC driver. This camera has a button on the top that allows a user to snap a still picture, so I would like to be able to capture both video as well as still images. In addition, I want to use the bulk transfer USB mode so that my image transfer will be error free. This means I want to use UVC still image transfer method 3.

I was able to use graphedit.exe, one of the tools in the tools in the Windows driver kit, to connect the camera driver’s video pin to a video rendering filter and the still pin to another video rendering filter which allowed me to alternately capture video or still images running the filter graph in graphedit- Cool! But, I couldn’t find any properties on the still pin to tell me which still image capture method was being used.

I used both UVCView.exe and KsStudio.exe provided by the WDK for AVStream Testing and Debugging to see if I could determine what still image capture method, or what USB transfer mode was being used, but to no avail. I couldn’t figure out how to decipher the descriptors reported by UVCView, and I couldn’t find a property related to still image transfer methods in any of the KsStudio filters that are related to USB video capture.

I don’t know whether still image transfer mode is a property of the MS UVC that can be set by an application, or is “hard wired” in the MS UVC implementation, or is hard wired in the device (the camera’s) UVC driver implementation. If anyone can shed some light on these questions I would be quite appreciative!

8/7/07 Update:  I’ve been told that the MS UVC driver will support still image transfer via a bulk pipe, but the firmware in the camera device needs to implement the bulk pipe, it’s not something that is determined by the application using the UVC driver.

This project to write an app that captures video from the UVC driver is on hold. My priorities have shifted elsewhere for now.

The DirectShow SDK (now part of the Windows SDK) includes a sample application called AMCap (Active Movie Capture) that illustrates the use of DirectShow filters to capture video from a device like a webcam or camcorder. I had all kinds of trouble the first few times I tried to build this, so I documented the steps for a successful build. Here they are:

These are the steps I followed to successfully build and run AMCap. I used Visual Studio 2005 Professional edition, SP1 for Vista, running on Windows Vista Business version . Note: the paths I have listed are the default installation paths and may be different on your computer.

A. Install the Windows SDK

1. Download and install the Windows SDK

2. Run ”Integrate Windows SDK with Visual Studio” from the “Visual Studio Registration” folder under “Windows SDK programs” on the start menu.

3. Reboot the computer.

B. Build the DirectShow base classes

1. Open the BaseClasses c++ solution (baseclasses.sln) using VS2005. The source code for the base classes is located in C:\Program Files\Microsoft SDKs\Windows\v6.0\Samples\Multimedia\DirectShow\BaseClasses.

2. Set the active configuration to “debug”

3. Build the solution.

C. Build AmCap

1. Open the solution.

2. Add the DirectShow include directory to the project properties under: “Property Pages - Configuration properties – C/C++ – General”. The path is: C:\Program Files\Microsoft SDKs\Windows\v6.0\Samples\Multimedia\DirectShow\Common

3. Add the path to the DirectShow base classes directory to the project properties. The path is: C:\Program Files\Microsoft SDKs\Windows\v6.0\Samples\Multimedia\DirectShow\BaseClasses\Debug

2. Build the solution.

3. Run it!

Here’s a helpful post at fungileo.com that explains how to install the DirectShow SDK. 

This article explains the steps needed to successfully installing DirectShow SDK into Microsoft Windows on the desktop. It guides you all the way from obtaining and installing the required SDKs, to configuring the environment, and finally, building a DirectShow application to verify the installation of the SDK.