> Followup to: <Pine.LNX.3.96.980914120636.10637O-100000@waste.org>
> By author: Oliver Xymoron <oxymoron@waste.org>
> > On 14 Sep 1998, Anders Melchiorsen wrote:
> >
> > > So a 4 hour video tape could carry like 60MB if your data is correct.
> >
> > If you only use the audio tracks. With a VGA-to-NTSC converter and a
> > framegrabber, you could up this number quite a bit. Assuming only
> > 320x200x8 resolution, grabbing only 15 frames a sec (below even VHS
> > quality), that's 64k/frame*15frames/sec*3600sec/hour=~ 3.5G/hour. Of
> > course, for the cost of a decent framegrabber, genlock, and VCR, you could
> > buy a good tape drive..
>
> There is no way you're going to get enough quality on NTSC to
> distinguish that many pixels reliably. Especially not recorded on
> VHS... But there *are* fairly cheap off-the-shelf devices that use
> VHS tape recorders as data storage media; they were popular in the
> early 90's.
Devices like the Alesis ADAT (and ADAT-XT etc) come to mind (since I used
it to record the instruments for a soundtrack a few years ago); it puts 8
channels of digital audio onto a SVHS videocassette. I think the ADAT
family has digital input and output ports as well. If we can recover even
half the bit-depth of CD quality, thats 8tracks * 44100 samples/sec *
8bits/sample * 1byte/8bits = 352800bytes/sec, aka 340K/sec, roughly
1.1gigs/hour. (If we can recover full 16-bit resolution, double that.
Sorry, I don't remember the playback bit-depth of the ADAT but I know you
could use 44.1KHz and 48KHz sample rates, among others...)
It's priced a little beyond the "consumer electronics" range though, so a
"backup to ADAT" driver probably won't be appearing for the Linux kernel
any time soon ;-)
Adam
-- You crucify all honesty \\Adam D. Bradley artdodge@cs.bu.edu No signs you see do you believe \\Boston University Computer Science And all your words just twist and turn\\ Grad Student and Linux Hacker Reviving just to crash and burn \\ <>< ---------> Why can't you listen as love screams everywhere? <--------
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