The Rohde & Schwarz R&S®VTC and R&S®VTE video testers assess audio/video signals from the user's perspective (application testing). They are used to evaluate signal quality and to identify faults reliably. The tests are based on a difference analysis between the audio/video signal being tested and a reference signal. The required synchronization can be achieved by using a unique identifier, called a time code. This time code is inserted using the R&S®Time Code Inserter software described in this application note. This application note describes how time codes work and how to add a time code to any A/V file.