Apparatus for and method of accurately obtaining the cycle time of completion of transmission of video frames within an isochronous stream of data transmitted over an IEEE 1394 serial bus network

摘要

In order to accurately obtain the cycle time at which transmission of a video frame, within an isochronous video stream of data, is complete, a command is added at the end of the video frame. The added command causes the value of the cycle time register to be read and recorded when the transmission of a video frame is complete. Preferably, the added command is a load quad command which records the value of the cycle time register within the command structure. When the transmitting application then receives the interrupt, notifying it that transmission of the video frame is complete, the application obtains the previously recorded cycle time value from the load quad command structure. Preferably, the video frame is part of an isochronous stream of video data which is transmitted over an IEEE 1394 serial bus network. In this manner, the cycle time corresponding to the completion of each video frame within the stream of data is accurately obtained.