Have you found a concert recording on videotape that you’re sure was supposed to be just an audio recording? You might be right, and you may have a PCM-format digital audio recording.
In 1981, Sony released a portable interface called the PCM-F1 that allowed one to record stereo 14 or 16-bit digital audio using an analog video recorder. It was a great idea and leveraged the higher bandwidth available on video decks like betamax and umatic.
So, if that betamax tape is labelled “digital audio”, bring it in and we’d love to have a listen.