Re: Not your father's Applicard

[MdntTrain <js@cimmeri.com>]

> He had no qualms about CDs.  The issue of "digital sound" with CDs is starting
> to verge on religous issues or possibly something as serious as vi vs. emacs
> :-).  I'll stay away from the discussion of whether or not it's lossy.

I'm surprised to hear you say that, as I thought it was pretty much
common knowledge now especially anyone who has mixed music for
recordings of the differences.  SACD is the only consumer digital
format that I can't tell is digital, except for the absence of analog
artifacts.

> How is VHS HiFi not digital?  Granted, it may not use PCM encoding (ISTR it's
> delta-encoding), but there's still an ADAC transformation of some sort.

My understanding (which is hardly definitive) is that it's pure
analog.  Here's a little blurb I excerpted from Wikipedia:

Around 1985, JVC added HiFi audio to VHS (in response to Betamax's
introduction of Beta Hi-Fi.) Both VHS HiFi and Betamax HiFi delivered
flat full-range frequency-response (20 Hz to 20 kHz), excellent 70 dB
S/N ratio (in consumer space, second only to the audio compact-disc),
and studio-grade channel-separation (more than 70dB.) This method of
VCR audio, known as audio frequency modulation (AFM), recorded each of
the 2 stereo channels (L, R) on a frequency-modulated carrier,
embedding the modulated audio-signal pair into the video-signal. To
avoid crosstalk and interference from the primary video-carrier, VHS's
implementation of AFM relied on a form of magnetic recording called
depth multiplexing. The modulated-audio carrier pair was placed under
the luminance carrier (below <1.6MHz), and recorded first.
Subsequently, the video-head erases and re-records the video-signal
over the same tape-surface, but video-signal's higher center-frequency
results in a shallower magnetization of the tape, allowing both the
video and residual AFM-audio signal to coexist on tape. (PAL versions
of Beta HiFi use this same technique.) During playback, VHS HiFi
recovers the depth-recorded AFM-signal by subtracting the audiohead's
signal (which contains the AFM-signal contaminated by a weak image of
the video-signal) from the videohead's signal (which contains only the
video-signal), then demodulates the left and right audio-channels from
their respective frequency-carriers. The end result of the complex
process was audio of outstanding fidelity, which was uniformly solid
across all tape-speeds (EP or SP.) Since JVC had gone through the
complexity of ensuring HiFi's backward compatibility with non-HiFi
VCRs, virtually all studio home-video releases contained HiFi
audiotracks (in addition to linear-stereo.)

JS

p.s.  Sorry, Alex.. this has nothing to do with the Applicard or my
father.