VCR Hi-Fi records/reads audio two ways:

The old analog way with the linear audio track on the long side of the tape.
This mode is FM and is backward compatable with non-HiFi recorded tapes.

The HiFi audio mode is Pulse Code Modulation. PCM is used to record audio
with the video head but separate from the video. The video head takes a
swipe across the tape. When it reaches near the bottom, it stops recording
video and starts recording DIGITAL audio using the same head.

During playback, the head listens for video sending it to the screen and
when it reaches the end of a swipe, shifts its attention to audio sending
the digits to a circuit that converts the signal back into stereo sound.

If the DIGITAL audio is not present on the tape the HiFi VCR will use the
old analog FM linear audio track instead.

In the 1980s and 1990s, some people used the Hi-Fi tracks on VHS and BetaMax
VCRs to record audio. This was a stopgap measure while affordable digital
audio was being developed and sounded far better than audio cassettes.

"David" wrote in message
...
On Thu, 27 Jul 2006 11:18:21 -0500, "SeeingEyeDog"
wrote:

If the VCR is of a stereo Hi-Fi vintage than the audio is recorded
digitally. It is fairly close to CD quality. Few people are aware of
this
fact.

FM, not digital.