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A7.6 Binary Epoch Standard Time

Binary Epoch Standard Time is a self-specifying binary time code based on a cumulative count of seconds and binary fractional subseconds since a known epoch used as a point of reference. A diagram illustrating the specific fields in the time format follows. It specifies values and contents of three fields: timecode identifier, coarse time, and fine time.

The chosen epoch is 00:00:00 hours UTC on January 1, 1950. This allows unambiguous identification of data from the epoch to 2086 A.D. Four bytes of coarse time represents approximately 136 years while the two bytes of fine time allow a resolution of approximately 15 microseconds.

TIMECODE FORMAT

OCTET (BYTE)

P = Timecode Identifier (8 bits)
CT = Coarse Time: elapsed seconds since epoch (32 bits)
FT = Binary sub-multiples of coarse time (16 bits): contains the fractional portion of a second with an assumed binary point to the left of byte 6.

TIMECODE IDENTIFIER

Figure A7-5 EDR/MDR Format Layout

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