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Serial Data Transport Interface is a way of transmitting data packets over a serial digital interface (SDI) datastream. This means that standard SDI infrastructure can be used.
Developed to address the needs of the growing number of compressed video standards ( DV, DVCPRO, BetaSX, MPEG2) it allows lossless transfer of data to other devices which have the same codec, for example DV to DV or SX to SX.
Using a standard SDI transport, the extra data is placed within normal active video, between Start of Active Video (SAV), and End of Active Video (EAV). This gives 1440 10-bit words of data at 270 Mbit/s (1920 words in the 8bit 360 Mbit/s standard).
If an SDTI stream is viewed using a standard SDI device, then the raw data can be seen as a small strip along the left-hand side (usually in purple). The DVCAM SDTI has video data at the top, control data in the middle ( Timecode, etc.) and audio at the bottom just like it is organised on the tape.
Because SDTI is used for compressed data the area used is less than a full screen; this allows for faster than realtime transfers.
SDTI is standardized as SMPTE 305M. A 1.5 GBit/s version, using the high definition serial digital interface, is standardized as SMPTE 348M.
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