A multimedia testing system is described herein that uses a virtual hardware driver to test software application behavior using virtual hardware in place of physical hardware devices. The virtual hardware driver receives customized input patterns that emulate behavior and formatting of data from a wide variety of hardware devices. For webcams, the system can send a steady stream of frames like those that would be provided as output from a physical webcam. A test environment can observe software interaction with the received customized input patterns to determine how the software will interact with various physical hardware devices. Thus, the multimedia testing system allows automated testing of a software application that interacts with multimedia hardware without physically buying and installing hardware devices.