Technicolor DTMF sequences

Many SP-mode videotapes duplicated at Technicolor Videocassette beginning in the late '80s and ending in the mid '00s 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 recording by providing information on settings such as format, running time, audio level balance, volume control, etc. to automatic video tape duplication machines. This allowed better replication of the master recordings. On certain pressings of CBS/Fox releases from 1989-1990, this sequence occurs during the still-framed 1984-1999 Fox FBI warning screen/1984-2000 CBS/Fox Video logo combo that likely occured on those pressings due to some sort of processing error.