Methods for embedding an out-of-band signal into a communication protocol capture stream

One or more out-of-band input signals (GPIO) are handled and efficiently embedded into a USB capture stream. In order to conserve resources, the state of the input signals can be sent only when a change occurs. The signals are accurately time-stamped, and then presented within the context of the captured USB data. In order to provide maximum visibility, if the digital inputs occur during a normally filtered multi-packet sequence, the filter is canceled and the surrounding packets will also be sent to an analysis computer. Furthermore, because digital inputs may happen during a USB packet, the digital inputs are queued in a FIFO buffer until there is an opportunity to send the digital inputs. Even though the state of the inputs may be sent at a later time, the state of the inputs may be time-stamped when the state of the inputs is perceived by the analyzer.