wjm@lcuxc.UUCP (B. Mitchell) (12/05/84)
Although the specs for VHS Hi-Fi look impressive, as have the reviews of some
prototypes, I still am somewhat concerned with the method of implementing it
(via multi-layer recording, where the lower frequency audio signals are
recorded first and then the video signals are recorded over them on the same
track. Since the lower frequencies penetrate deeper into the tape, the
video recording does not erase the audio recording. Note that the same track
is used for both video and hi-fi audio.) in mass production.
I prefer the Beta Hi-Fi approach where the audio signals are FM modulated
and inserted into an unused frequency band of the composite video signal
(around 1.5MHz, I think) and then the total video+audio signal is recorded on
the video track.
Note that the hi-fi audio on both Beta Hi-Fi and VHS Hi-Fi is separate from the
lo-fi stereo provided by the the conventional audio tracks. You can put 6
separate sound channels (4 hi-fi and 2 garbage) onto a Hi-Fi videocassette:
1&2 the two Hi-Fi channels
3&4 use a PCM processor to put two digital Hi-Fi channels in place of a video
signal.
Garbage1 & Garbage 2 the two abyssmally low quality conventional audio channels
VHS Hi-Fi is upwardly compatible with conventional VHS (pre-recorded tapes
provide garbage versions of the Hi-Fi audio on the standard audio tracks),
and you can play older VHS tapes on a VHS Hi-Fi machine (but you will only get
the low quality audio from the conventional tracks).
The same applies to Beta Hi-Fi and standard Beta. Of course, Beta Hi-Fi and
VHS Hi-Fi are totally incompatable just like standard Beta and VHS.
My recommendations: If you're buying the Hi-Fi VCR just to use as a high
quality audio recorder (or to record the output of a PCM processor) or
just to record video off the air - go with Beta. I think the Beta Hi-Fi system
is more robust and less likely to provide technical problems. Also, its specs
are slightly better (although VHS Hi-Fi is quite good, and better than most
other analog recording techniques).
Also, I've heard the Beta system provides a slightly better video image (but
that's a discussion for net.video not here)
Also, Beta videocassettes are a bit smaller than the VHS variety.
On the other hand, if you swap tapes with your friends or use/rent/buy
many prerecorded tapes, keep in mind that VHS is the more popular format
and you may want to go the VHS route.
Also, VHS tapes can play longer (up to 8 hours at the slowest speed, with T160
tapes, as compared to 5.5 hours for L830 Beta tapes).
Regards,
Bill Mitchell ({ihnp4!}lcuxc!wjm)