One of the benefits of serial digital audio and video is the ability to multiplex AES/EBU digital audio with a serial digital video signal. As a result, a single coaxial cable carrying serial component digital video will accommodate up to 12 channels of digital audio. On the other hand, a single coax carrying composite NTSC and PAL digital video will support up to four channels of digital audio. This multiplexed signal can be easily distributed around a facility using existing video patch panels or a serial digital video routing switcher. In addition, other ancillary data, such as time code and source identification information, can also be multiplexed into the same serial digital bit stream. Once these signals have been multiplexed and distributed, it may be necessary to demultiplex the digital audio and other ancillary data from the video to treat those signals independently. This is particularly important in post-production. SMPTE has proposed an audio digital standard, Formatting AES/EBU Audio and Auxiliary Data into Digital Video Ancillary Data Space, which is in committee. The AES audio format is AES3–1992, and is referred to as “AES,” or a 20-bit subset thereof. Details of the proposed specification are described in this article. Also discussed are practical multiplexers and demultiplexers, systems issues such as audio/video timing, and considerations for distribution of AES/EBU audio via twisted shielded pair audio cable versus video coaxial cable.