Technicolor DTMF sequences

Many SP-mode videotapes duplicated at Technicolor Videocassette beginning in mid 1989 and ending in mid 2003 included a sequence of DTMF phone-dial tones at the start and/or end of the tape. On certain tapes with this sequence, a faint sound of extra tones precedes it. It is not yet known exactly what each tone in the sequence indicates, except there's usually a pause between the first and second tones, the second tone is always 1, the third tone is always #, and the fourth tone is always D. This sequence was used to encode information on the master tape by providing information on settings such as format, running time, audio level balance, volume control, etc. to automatic videotape duplication machines. This allowed better replication of the master tapes that were copied onto the formats the videotapes were released in.

Oddities About This Sequence on Certain VHS Tapes

 * On certain pressings of CBS/Fox releases from 1989-1990, this sequence occurs during the still-framed 1983-1999 Fox FBI warning screen/1984-2000 CBS/Fox Video logo combo that likely occured at the start of those pressings due to some sort of processing error.
 * On some VHS tapes released by Buena Vista Home Entertainment, this sequence occurs during the FBI warning screens.