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

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Subject: Re: [linux-audio-dev] Final Scratch, custom kernel?
From: Juan K. (kungfu_AT_cmu.edu)
Date: Mon Oct 07 2002 - 23:29:37 EEST


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) > >


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