here's how i do it:
1st channel:
1.5khz control tone
2nd channel:
bits encoded as follows:
0 : 1 3khz cycle
1 : 2 6khz cycles
marker: 1 1.5khz cycle
so each timecode looks like this:
marker cycle
encoded 0
checksummed bit sequence
encoded 1
marker cycle
each one ends up being about 8ms. so my "latency" is better than theirs!
[i'm pretty sure finalscratch's 12ms assumes the record is moving at
normal speed]
since the frequencies are multiples of each other, the crosstalk from the
cutting head or even from the cartridge that gets used is mitigated
the 0 and 1 starter bits help figure out what's going on depending if the
record is playing backwards or forwards
counting zero crossings works...but don't forget to filter out the low
frequencies [like 80hz and below], since the noise from the person's hand
will fuck things up
i'm fiending to buy one of the finalscratch control records [the guys at
platinum are telling me they're gonna be like 25 dollars], to see what
they're doing
--
John Ketchpaw
kungfu(a)alumni.cmu.edu
On Mon, 7 Oct 2002, CK wrote:
I read:
Well i guess encoding absolute time should not be
too hard.
A simple solution could be to have the two stereo channels with different
frequencies, with the ratio corresponding to the radial position.
forget it there is no such thing as a clean channel separation on
vinyl.
regards,
x
--
chris(a)lo-res.org Postmodernism is german romanticism with better
http://pilot.fm/ special effects. (Jeff Keuss / via
ctheory.com)