Dear All,
My apologies for being late entering this discussion, I was on "summer
holiday" (last week and the week before!). I should like to contribute
something from the *audio* point of view.
For the purposes of long-term preservation of the audio accompanying
both VHS and S-VHS tapes, we "clone" onto blank S-VHS tapes. This
approximately doubles the signal-strength of everything, the luminance, the
chrominance, and the two "hi-fi" channels. The editing pair automatically
optimises the carrier levels for the chrome-doped ferric S-VHS tape. I have
put the word "clone" in quotation marks, because we use a VHS/S-VHS editing
pair operating in the "dub" mode, which copies all the RF carriers without
demodulating them to baseband. The plavback machine recognises whether the
original was to the VHS or S-VHS format by measuring the luminance carrier
frequency. We also "copy" our Betamax and VHS versions of the Sony PCM-F1
format onto S-VHS tape, using the digital editor's ability to record VHS
luminance frequencies if required. In this case, the word "copy" is Sony's
word meaning "copying the digital data in the video waveform with error
correction". If the same audio isn't available on the linear and Hi-Fi
tracks, we add them, since it is much easier to search for things on a VHS
editor (even without my notorious ability to *see* and edit the audio by
looking at the digitised pictures).
Since both the VHS and S-VHS formats were invented by JVC, we use their
make of blank tape. I also use S-VHS for video applications at home, and my
subjective experience is that no other S-VHS tape is as good from the points
of view of chroma noise or dropouts.
All this evidence suggests that, for something originating on VHS,
VHS-C, S-VHS, or S-VHS-C, preservation may be optimised by this strategy.
Reverting to audio considerations, a live broadcast of (say) a music concert
in the early 1990s recorded with hi-fi tracks, may end up with better sound
quality than (say) C-format videotapes in the broadcaster's own vaults.
Peter Copeland
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