vertical interval time code (video) (VITC)
The Vertical Interval Time Code (VITC) is a time code used in the video sector for synchronizing video sequences. It was standardized by the Society of Motion Picture and Television Engineers( SMPTE) and, like the Longitudinal Time Code( LTC), contains information about the date, hours, minutes, seconds and field and is inserted in several blank lines in the vertical blanking interval of the television picture.
In the VITC time code, each digit of the decimal system is represented by a 4-digit BCD code. The VITC time code cannot be subsequently changed.
The different video recording formats use different blank lines for keying the VITC time code. In Betacam, for example, these are blank lines 9 and 11 in the first field and blank lines 322 and 324 in the second field.
Since the insertion is done in the fields, the VITC time code is permanently present. The difference between the VITC code and the Longitudinal Time Code (LTC) is that the VITC time code can be read out during slow forward and still frames, while the LTC code can only be read out when the magnetic tape is running. On the other hand, the VITC time code can cause difficulties in reading out when the tape is running fast.
For SDI signals ofdigital video, the SMPTE has specified the digital version of the VITC time code, the Digital Vertical Time Code( DVITC). However, digital video also uses the Ancillary Time Code( ATC).