[geeks] bizarre stuff available

[Yuri K]

Hello Joshua,

Wednesday, December 11, 2002, 21:09:16 (UTC), you wrote:

JDB> In theory a decent HiFi VCR should be very good for audio,
JDB> what with the width of the tape, and isn't it a pretty fast tape speed
JDB> also?

They always use helical scan for video, yet audio is a bit different story.
Sound for the VHS format is not merged into the video signal on the
tape.

1.  For non-Hi-Fi VHS VCRs, a separate stationary tape head is
responsible for the audio signal.

(Sorry for possibley incorrect terminilogy, my training was done in a
different language years ago).

Due to the very slow tape speed, audio quality is not
even comparable to a cheap audio cassette player even at the SP speed.


2.  VHS Hi-Fi overcomes this by FM recording of the audio signal deep in the
tape (recorded by a separate set of Hi-Fi heads just before the video
information), actually buried under the video information.
The left and right audio channels are recorded in separate frequency
bands - centered around 1.3 and 1.7 MHz respectively.
The azimuth angles for the HiFi audio heads are  +/- 30 degrees which
minimizes intermodulation errors (crosstalk?) between the recorded
Hi-Fi audio and video information.

Since the head-tape speed for the VHS audio track is the same high
rate as for the video track and exceeds that of a typical audio
cassette deck by a factor of more than 100, VHS Hi-Fi audio
reproduction - frequency response, signal to noise ratio,
and dynamic range - is excellent and approaches that of a CD.
In fact, using a T120 video cassette in EP (SLP, 6 hour)
mode simply to record stereo music (with the video ignored or blanked)
is extremely cost effective.  What other media/technology will store a
6 hour concert with nearly perfect reproduction for under $2?
For some rare records I use standard LP, e.g. I managed to find
non-digitized vinyl release of Temptations "Zoom" and put it on LP
speed for later hobbying.

There are few disadvantages to VHS HiFi, however, notably:

    it is not possible to re-record (dub) only the audio
    without disturbing the video.

A good grade VCRs usually take care of those, especially true SVHS
models. I don't know anything about new digital formats, they may even
be better, but VHS is very cost efficient. That's what we always did
decades ago in SU.


JDB> One word.  FLAC.

         What is FLAC, please?


-- 
Best regards,
 Yuri 

''Get your facts first, and then you can distort them as much as 
you please.'' - Mark Twain