Asynchronous Serial Interface - ASI, DVB-ASI

ASI stream, defined in the DVB document A010 (Interfaces for CATV/SMATV Headends and Similar professional equipment). It can contain a single program or a multiplex of multiple programs, each program containing video and audio.

SD or HD content is compressed as a MPEG-2 (SD) or MPEG-4 (HD) stream with an appropriate encoder. The compressed stream is wrapped into an MPEG transport stream in an DVB-ASI signal. The DVB-ASI operates always at 270 Mbps, regardless of the compression rate of the payload.

MPEG-2 data streams can be in the DVB-ASI format or the SMPTE 310M format. The SMPTE-310M was originally developed for point-to-point low noise transmission within the studio and has a transfer rate of 19.39 Mbps, DVB-ASI was developed for transport over longer distances (with acceptable higher noise rates) and has a varying MPEG-2 payload rate of up to 213.7 Mbps. But most times the DVB-ASI payload is much less than the possible maximum.
See: SMPTE-310M.