[linux-audio-dev] Final Scratch, custom kernel?

[Juan K.]

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 at 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 at lo-res.org	Postmodernism is german romanticism with better
> http://pilot.fm/	special effects. (Jeff Keuss / via ctheory.com)
>
>