Post by Kenn CaesiusCan anyone explain some of the technical aspects of the SVHS-ET format
that supposedly make it better than VHS?
I have nothing but negative experiences using the format - SVHS-ET SLP
recording tests were unwatchable while SP tests produced nearly
imperceptible improvements, though I will admit that I was using
standard grade tape, but come on, is there any real difference between
standard, high, and extra high grade tape nowadays?
In the days of S-VHS, which required special high coercivity videotape, it
was discovered that recorders could be tricked into laying down the same
signal on a conventional-grade tape. The VCR distinuished between VHS and
S-VHS blanks by means of a sensing hole on the bottom of the cassette. By
drilling out a hole, the recorder would use S-VHS mode on a conventional
blank. This basically meant expanding the luminance bandwidth to increase
the horizontal resolution slightly. On conventional tapes, the results
were mixed. Using premium tape and the SP speed, you could get near SVHS
resolution with a propensity towards higher noise and dropouts. Doing this
in EP/SLP speed usually produced very noisy, almost unwatchable results.
Of course these tapes would not play at all on a conventional VCR, as the
high luminance signal simply washed out the whole picture.
S-VHS ET was an attempt to apply some of these concepts in a more
compatible way. The luma bandwidth was expanded (using companding, as I
remember) so that pseudo-SVHS encoding could be more reliably recorded on
a standard quality video tape. This was iffy technology which required a
bias and equalization tweak on each new blank prior to use. The attraction
was that VCR's capable of playing in SQPB mode would play these tapes with
enhanced resolution, and standard VHS VCR's would play these tapes back
looking like, well, standard VHS (rather than washed-out noise which would
be the result of attempting playback of as true S-VHS recording).
As you've discovered, this works to some degree in SP mode, but EP/SLP is a
mess no matter how you slice or try to enhance it. YMMV.