$0ff|1-Pesky Video Copy Protection



$0ccRecently me and my flatmate each bought a funky reconditioned Sony Nicam
VCR with all the pro edit jog shuttle gubbins for £140 - they would have
set  you back £500 when new.  Now having two top VCRs in the house opens
up  an  excellent  opportunity  for  you to "back up" your tapes.  Ahem.
Incase they get chewed up or something.

$0ffThe  problem  is  that  most  pre-recorded  tapes now include some quite
clever  copy protection scemes.  No matter how we connected the VCRs the
best  results  we  could  get  were  grainy,  scrolling, black and white
pictures.

$0ccHow does this work then?  Well some very dodgy pulses are recorded on to
the  tape in such a way that they do not affect playback or display on a
TV,  but  if  you  atempt  to record the signal they severly confuse the
recording VCR, screwing up all the tracking on the recording.

$0ffHow  do you get around this?  Well, you may be lucky and have a VCR that
is  very  tolerant  of the dodgy signals.  Infact the makers of the copy
protection system claim it works with "90% of domestic VCRs" leaving 10%
that it doesn't affect.

$0ccYou can try to filter out the pulses using an expensive and hard to come
by  bit  of  electronics kit.  Even then, this is not guarenteed to work
with  all  tapes as the pattern of pulses used can vary widely from tape
to  tape.   If  you are clever enough, and a dab hand with the soldering
iron,  there  are  scematics for building such a device available on the
net, but it's a tad complicated.

$0ffMy  method,  however,  is even more clever :) I feed the composite video
output  from  the VCR into my WinTV card.  I then set my Xpert@Play card
to  800x600 TV output mode, and then connect this to the composite input
on  the  recording VCR.  Then simply connect the audio with some phonos,
set WinTV to display full screen, and record away!

$0ccIn  effect, the WinTV card is digitising the video, totally ignoring the
dodgy  pulses  in  the  signal,  and  then  scaling  it up to 800x600 in
hardware.  This data is then transfered directly across the PCI bus into
the  graphics  card  memory,  where  it is converted back to a PAL sized
analogue  signal, and outputted to tape.  What's more, this process uses
ZERO cpu power.  Everthing is handled by the graphics cards over the PCI
bus.

$0ffThe  end  result  is  usually  a better quality signal than the original
tape!   This  is  due  to  the  comprehensive  controls over saturation,
brightness, gamma, contrast, luma/chroma flicker removal, sharpness, dot
crawl  and  colour  balance  all  of which can be tweaked in the display
properties for the ATI card.

$0ccOne  "feature"  of  the  ATI  card  is that it will not do full vertical
overscan,  so  the final movie is recorded with a very slight widescreen
effect, which I actually quite like.  You don't actually lose any of the
picture, it is just squashed a bit, although you can't tell.

$0ffAnother  advantage  of this technique is that it can be used to clean up
weak  video  signals.   Recording a poor tape using this method will not
improve  the  play  back  quality  much, but by recording a full stength
signal  from  the  pc,  perfect  still  frame  and picture search can be
restored,  without  a  rolling  black  and white picture, much enhancing
those  dodgy  old  pornos.  This is also usefull if you want to edit the
tape, repairing "drop outs" (loss of a solid signal) which can cause big
problems with editing equipment.

$0ccend.