Kara GoldfinchI remember some VHS tapes I had when I were little played seemingly random DTMF tones at the beginning. I wondered why for years and have just found out.
From Wikipedia:
"DTMF signaling tones may also be heard at the start and/or end of some prerecorded VHS videocassettes. Information on the master version of the videotape is encoded in the DTMF tones. The encoded tones provide information to automatic duplication machines, such as format, duration and volume levels in order to replicate the original video as closely as possible."
So there you go.
From https://en.wikipedia.org/wiki/DTMF_signaling
From Wikipedia:
"DTMF signaling tones may also be heard at the start and/or end of some prerecorded VHS videocassettes. Information on the master version of the videotape is encoded in the DTMF tones. The encoded tones provide information to automatic duplication machines, such as format, duration and volume levels in order to replicate the original video as closely as possible."
So there you go.
From https://en.wikipedia.org/wiki/DTMF_signaling
Andrew Hodgson