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

[Lance Blisters]

  Great!  What are you using to decode the audio signal?  How can 
  other software program against it?

  As there are several implementations of timecode-on-vinyl, perhaps
  the authors can agree on a format for realtime position/rate data.
  I can imagine other custom controllers which would fall into this 
  category.  I don't suppose there is an existing standard of some sort
  which would be sufficient?

  -geoff


On Mon, Oct 07, 2002 at 04:28:26PM -0400, Juan K. wrote:
> 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)
> >
> >
>