Timecode bit assignment table

This table illustrates the assignment of bits in longitudinal (LTC) and vertical (VITC) timecode. See the associated document Technical Introduction to Timecode.

Transmission order is right to left, top to bottom - that is, least significant to most significant. For VITC, start with the rightmost column VITC sync and include the final row of VITC sync and CRC bits. For LTC, exclude the VITC sync columns and include two final rows of sync A and sync B bits.

7 6 5 4 3 2 1 0 VITC sync
0 1st binary group Frames units 0-9 0 1
8 2nd binary group
(or character 0)
Color frame flag Drop frame flag Frame tens 0-2 0 1
16 3rd binary group Seconds units 0-9 0 1
24 4th binary group
(or character 1)
Parity/
Field mark
Seconds tens 0-5 0 1
32 5th binary group Minutes units 0-9 0 1
40 6th binary group
(or character 2)
Binary group flag B Minutes tens 0-5 0 1
48 7th binary group Hours units 0-9 0 1
56 8th binary group
(or character 3)
Binary group flag A Unassigned Hours tens 0-2 0 1

In vertical interval code, the VITC sync and information bits are followed by 2 VITC sync bits, then 8 cyclic redundancy check (CRC) bits computed across the preceding 82 bits:
7 6 5 4 3 2 1 0 VITC sync
CRC G ( x ) = x 8 + 1 0 1

In LTC the 64 information bits are followed by 16 LTC synchronization bits:
7 6 5 4 3 2 1 0
sync A 1 1 1 1 1 1 0 0
sync B 1 0 1 1 1 1 1 1

This material is excerpted from Chapter 21, Timecode, of my book A Technical Introduction to Digital Video, copyright John Wiley & Sons, 1996. I encourage you to read this note online, but please do not reproduce it: reproduction of this note is prohibited according to the terms of my agreement with the publisher.

Charles - Video engineering - Timecode
1997-07-13