This is going to be a follow-up video to the previous one in which I encoded some
data into some music and then recorded it directly onto a Digital Audio Tape in
audio format. This is the wrong way to backup data but I wanted to see if it
was going to be actually possible to do it. Now I need to test to see that the
data is actually on here, inside the music. And the best way to prove that the
data was successfully recorded onto this tape is to recover it off here.
The first problem is that while most computer mainboards do have digital audio output. They
generally don't have any sort of digital audio input. So I need an SPDIF input on
a computer so that I can play this tape and then capture the data off it. There
are high-end sound cards that have SPDIF digital audio input but they are
expensive, and outside the scope of this test.
Fortunately Apple have put digital audio input into many Macintoshes. Cleverly
hidden inside the three-and-a-half millimeter analog audio input jack, is an
optical Toslink port. Now optical Toslink or Toshiba-Link where the name comes
from, uses a plastic optical tube to transmit digital audio. The format is the
same as SPDIF and so a simple converter can be used.
Despite Toslink having been invented in the 1980s there is still something that
feels quite futuristic about passing music as light over a clear tube. We know
from the previous video that this port here is not fully SPDIF compliant and
uses a 5 volt signaling. Instead of half a volt as SPDIF requires. And I don't
have a cable that can convert for output. So I'm actually going to be just poking
wires directly into this, and then feeding that 5 volt signal into the
converter box which is expecting only half a volt. But that should be fine. Now
for the actual recording of the audio on the Macintosh, I did do some research
into Macintosh 'bit perfect' audio recording, and there is a program called
Reaper that should record the bits exactly as they're coming into the
digital audio port. Xo I'm now going to put this into motion and do the
recording process. OK finally forty-four minutes later and I've played
the entire recording back into the Macintosh and captured it as a WAV file
for stereo. The results are in. I've tested the recorded audio with deep
sound back on the Windows machine and sure enough, there is all the data as I
saved it. So I now know that this is a backup of
both the music and the data encoded into the music. So this whole process has
shown that even though it's not really the right way to do it. You can actually
backup data on to a Digital Audio Tape and leave your data to the whim of
whatever error detection and correction is going on inside your Digital Audio
Tape recorder. And it also means that if I want to make bit perfect copies of
Digital Audio Tapes I now know that I can using the Macintosh and the optical
digital input. The whole process now complete, and I've backed up data onto a
Digital Audio Tape and then successfully recovered it. I thought about some other
wrong ways that I could backup data and what I'd like to try is putting data
onto a mini DV digital video cassette, and these are certainly not designed to
hold computer data. Yet there's an easy way that it can be done. So I'd like to
try that and as a bit of a challenge. I want to backup data onto a micro MV
because there's no easy way to do this but this is the world's smallest video
tape and that would be really interesting to try that. So that's it for
now. We're done and I thought would fade out with some what's Rangoon To You Is
Grafton To Me. When the night comes down around your collar and the road starts
coming up through your headlights for MIDI landscape suddenly isn't its dream
time for the land of legends somewhere out there
and we lost I was taking another suite inside the car I'm making final
adjustments to the viewing screen a holden windshield where tonight's travel
thriller is being shown at 70 mile per hour not so much the cars that a parrot